Application of defecation lime from sugar industry in Uzbekistan

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KTH Chemical Engineering and Technology

Application of defecation lime from sugar industry

in Uzbekistan

M A S H A R I P O V A S H O I R A

Master of Science Thesis Stockholm 2006

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KTH Chemical Engineering and Technology

Masharipova Shoira

Master of Science Thesis

STOCKHOLM 2006

A PPLICATION OF DEFECATION LIME FROM SUGAR INDUSTRY IN U ^ZBEKISTAN

PRESENTED AT

INDUSTRIAL ECOLOGY

Supervisor & Examiner:

Monika Olsson

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TRITA-KET-IM 2006:3 ISSN 1402-7615

Industrial Ecology,

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Abstract

This Master Thesis “Application of defecation lime from sugar industry in Uzbekistan” is done in the Master’s Programme in Sustainable Technology at the Royal Institute of Technology (KTH).

In this project Khorezm Sugar Company, operations in the factory and environmental problems in it have been studied.

Impacts of defecation lime were described. The waste causes a lot of environmental and economical problems in the region. As it is dry and consists of particles with small size, defecat is easy spread able with the wind. It swells to nearest areas and could have impact on biodiversity as well as on health of people.

Different modern methods of handling the defecation lime in Europe and Asian countries and new methods that are not in practice in large scales yet, were also described.

These methods, such as: use of defecation lime as a soil improver, as a fertilizer, as an additive in greenhouse soil mixture, as a sorbent to treat waste water, as a micro filler in cement production and foam concrete production and as a mineral additive in animal feeding.

Advantages and disadvantages of these methods were examined.

As an example the British Sugar and the LimeX division of the company were described. They obtain the same type of waste from sugar production. And use defecation lime as a soil improver to stabilize soil pH, to add organic matters to soil and improve soil structure. The defecation lime is sold by 3 brands in the company, like: LimeX 45, LimeX 70 and LimeX Super70 M. What they are doing and how they treat are described.

As the main treatment method in the other sugar manufacturing companies, use of defecat as a soil improver was studied deeply. Therefore, soil characters of Uzbekistan have also been described. The fertilizer need in the country, especially in Khorezm region and crops need for organic matters were overviewed.

Different treatment methods of defecation lime, which are described in the thesis, are discussed to apply them in Khorezm Sugar. During discussing and suggesting methods technological and economical features have been taken into account.

As a main type of treatment to use defecation lime in cement and foam concrete production were suggested.

Also, use defecat as a soil improver and as additional methods, use of defecation lime as an additive in greenhouse soil mixture and to use as a sorbent to treat waste water were recommended.

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Acknowledgement

It was a great experience for me working on this Thesis Work at the Royal Institute of Technology (KTH) and visiting the British Sugar Company also learning about different methods of treatment of defecation lime.

I am very thankful to Abdusharib Ruzimov, the director of the Private Company

“Javlon” for all the help and support, especially, on choosing my thesis Work theme and giving very good ideas, at all sharing his knowledge and experience.

I am very appreciative to Monika Olsson, my supervisor from the KTH, who brought me into the Waste Management field and helped at the same time. I would like to thank her for continual support during this work, for many hours discussions we had, for her every careful adjustment and remarks, for helping me to find right answers to difficult questions, for encouraging in the entire step and all the teachers at Industrial Ecology for sharing their knowledge.

I would like to thank the Management of British Sugar, that they allowed me to visit the factory and created very good conditions during my study visit.

I am very grateful to Richard Cogman, the national manager of LimeX division of British Sugar, who was always glad to help me in a lot of my questions, who gave me a lot of advices, arranged meetings with the people in all 3 factories, which we visited together, for his and his family's hospitality and for all the great memories in Norwich..

I would like to extend my gratitude to Sherzod Qurambaev, my teacher in Uzbekistan, for his valuable support in difficult times and for his advice. Also, my gratefulness goes to all teachers at Urgench State University.

My great thanks go to Dilfuza Egamberdieva, who helped me to find necessary information about agriculture of Uzbekistan, for her sharing information with me, for her understanding.

My great thanks and respect are to my special friend in London, for his everyday support and encouraging during this work, for his every time understanding, for his care and for making me not feeling lonely even from distance.

Also, I would like to thank my friends Galya and Inobat for their help in different things concerning my thesis and to other group-mates for all the times we shared in Sweden.

Especially, Galya for her understanding and help, for sharing her experience and for all she has done for me.

My love, gratefulness and appreciation go to my family in Urgench in Uzbekistan, especially my brother, who always supported me from distance.

My love and gratitude to my parents for their trust on me, for their support and all they have done for me. And I am grateful to my Uzbek friends Nargiza, Sardor and others for their help and understanding.

And also the God, for his unlimited gifts and blessings…

Stockholm, 2006 Shoira Masharipova

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List of figures

Figure-1.1. Map of Uzbekistan……….11

Figure-3.1.LimeX70 products storage at The Bury St Edmunds Sugar Factory ……….19

Ficure-3.2.Newly pumped and stored LimeX45 products in Cantley Sugar Factory ………..20

Ficure-3.3.Pressed LimeX70 and its storage in The Wissington Sugar Factory ……….20

Figure.3.4. Beet receiving ………...……….21

Figure.3.5. Beet washing…..………21

Figure.3.6. Slicing machine ……….... 21

Figure.3.7. Diffusion……….……....21

Figure.3.8. Filters ……….….…...22

Figure.4.1. Sugar beet yield……….……… 23

Figure.4.2. Photosynthesis ……...………23

Figure-4.3. Sugar beet content ……….24

Figure-4.4. Beet handling ……….25

Figure-4.5.Diffusion process ………26

Figure-4.6.Pulp dryer ………...27

Figure-4.7.Lime Kiln ………...28

Figure-4.8.Purification and filtration ………...29

Figure-4.9. Evaporation process ………..30

Figure-4.10.Crystallization and Separation ……….31

Figure-4.11.Molasses desugarization ………...32

Figure-6.1. Particle size comparison of liming products ……….46

Figure-6.2. Yield response when LimeX 70 is applied ………47

Figure-6.3. pH Increase on grassland where LimeX applied ………...48

Figure-7.1. Dominant soil map of Uzbekistan ……….50

Figure-7.2. Agricultural area ………51

Figure-7.3. Cotton and wheat production, 1992 to 2002 ……….…52

Figure-7.4. Number of different types of farms ………...53

Figure-7.5. Soils classification on the quality (%) ………...54

Figure-8.1.Handling of defecation lime in the world ………..……….60

Figure-8.2.Handling of defecation lime in the world ………...61

Figure-8.3 a) Loading (a) and spreading (b) of LimeX and the limed field (c) ………...63

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List of tables

Table-1.1.Chemical content of defecation lime in Khorezm Sugar Company ………15

Table-3.1. LimeX production by factories (2005/06 year: estimated production/K tonnes)…18 Table-5.1. pH ranges ………....35

Table-5.2.Approximately doses of the limestone to introduce into the soil (in grams at the depth of 20 cm on one square meter) …...36

Table-5.3. Plants and pH values suitable for them …….……….37

Table-5.4. Composition of the defecat ……….…39

Table-5.5. Influence of the doses of the used defecat on productivity of tomato …………....39

Table-5.6. Influence of the doses of the used defecat on productivity of sugar beet …….…..39

Table-5.7. Technical requirements for lime flour ………43

Table-6.1. Nutrients in LimeX and their amount ……….45

Table-6.2. Application rates for LimeX 70 (for 1 pH unit increase) ………...46

Table-6.3. Application rates for LimeX 45 (for 1 pH unit increase) ………...46

Table-7.1.Main types of soil by local classification and their humus content ……….55

Table-7.2.Average standard rates of fertilizer application for the main agricultural crops (kg nutrient/ha) ………...57

Table-7.3. Main crops, use of mineral fertilizers and yields ………58

Table-7.4. Main crops: rates of fertilization ……….58

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Glossary of terms

Acidity - soil is said to be acidic if its pH value is below 7 (see also – pH and alkaline).

Alkalinity – soils with pH value above 7 (see also pH and acidity).

Arable land - (from Latin arare, to plough) is a form of agricultural land use, meaning land that can be used for growing crops.

Arid - Lacking moisture, especially having insufficient rainfall to support trees or woody plants.

Buffering - the components of a soil solution that can neutralize either an acid or a base and which maintain a constant pH.

Campaign – sugar beet processing season.

Carbokalk – calcium containing waste of beet sugar processing.

Clay - Clay is one of the three principal types of soil, the other two being sand and loam. A certain amount of clay is a desirable constituent of soil, since it binds other kinds of particles together and makes the whole retentive of water.

Crystallization – formation of crystals from a concentrated liquid.

Defecate - to remove impurities, as in a chemical solution, clarify.

Defecation lime – calcium containing waste from sugar industry

Dolomite - a white or light-coloured mineral, essentially CaMg (CO3)2, used in fertilizer and as a construction and ceramic material.

Extraction – separation one material from another, for example sugar from sugar beet.

Fertilizer - Any of a large number of natural and synthetic materials, including manure and nitrogen, phosphorus, and potassium compounds, spread on or worked into soil to increase its capacity to support plant growth.

Humus - A brown or black organic substance consisting of partially or wholly decayed vegetable or animal matter that provides nutrients for plants and increases the ability of soil to retain water.

Lime - a general term for various naturally occurring minerals and materials derived from them in which carbonates, oxides and hydroxides of calcium predominate. The chemical formula for lime is CaO (calcium oxide).

Lime kiln - a kiln used to produce quicklime by the calcinations of limestone (calcium carbonate).

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LimeX – the brand, by-product of British Sugar

Limestone - A common sedimentary rock consisting mostly of calcium carbonate, CaCO3, used as a building stone and in the manufacture of lime, carbon dioxide, and cement.

Liming - application to the soil of calcium in various forms.

Loamy - soil composed of a mixture of sand, clay, silt, and organic matter

Milk of lime - Ca (OH) 2, colourless crystal or white powder. It is prepared by reacting calcium oxide (lime) with water; a process called slaking, and is also known as hydrated lime or slaked lime.

Molasses - thick syrup produced in refining raw sugar and ranging from light to dark brown in colour.

Purification - is the process of separating a substance of interest from foreign or contaminating elements.

Salinity - the accumulation of free salts to such an extent that it leads to degradation of soils and vegetation.

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Abbreviations

BOD - Biochemical Oxygen Demand COD - Chemical Oxygen Demand

CIS - Commonwealth of Independent States GDP - Gross Domestic Product

JSC – Joint Stock Company

LTD – Limited (in company names)

MAWRRUz – Ministry of Agriculture and Water Resources of the Republic of Uzbekistan µm - A unit of length equal to one thousandth (10^-3) of a millimetres or one millionth (10^-6) of a meter, also called micron

pH - Soil pH or soil reaction is an indication of the acidity or alkalinity of soil and is measured in pH units. Soil pH is defined as the negative logarithm of the hydrogen ion concentration. The pH scale goes from 0 to 14 with pH 7 as the neutral point. As the amount of hydrogen ions in the soil increases, the soil pH decreases thus becoming more acidic. From pH 7 to 0 the soil is increasingly more acidic and from pH 7 to 14 the soil is increasingly more alkaline or basic.

PC – Private Company

PCC – Precipitated Calcium Carbonate SCLR – State Committee for Land Resources UK – United Kingdom

US – United States

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1. Introduction

Sugar manufacturing plant has typical environmental impacts such as: wastewater, air emissions and solid waste.

Wastewater comes from washing raw materials, from the boiler house (boiler blow- down water), extract purification in the evaporation and boiling station (excess condensate and purification water), refining (regeneration water from the ion exchange resins), site cleaning and sometimes rainfall.

Emissions into air, occur from the boiler plant (flue gases from processes in which solid, liquid and gaseous combustibles are burnt), airborne substances (flue ash), raw material processing, extraction, juice purification and juice concentration (ammonia).

Almost all sugar manufacturing factories obtain defecation lime from the production process. In some countries it is treated in some way, but there are still some of them which do not have any solution.

The only sugar producing plant in Uzbekistan is Khorezm Sugar (in the figure-1.1, you can see the map of Uzbekistan).

Defecation lime at Khorezm Sugar Company has not been used in any purposes.

However, there is a chance to use it as a raw material for other branches of industry or agriculture.

British Sugar is one of the leading sugar manufacturers in the world. They have processed and used defecation lime for about 70 years. Until now they have been using defecat in agricultural purposes.

The Company has a good environmental care. They also, make some profit from using of waste in some way. Specialists in the company control the work in a proper way and the process is managed well.

The use of waste in some way satisfies the need for raw materials in some industries applied, reduces expenditure for the new ones, clear out large areas where the waste is placed today and eliminates environmental pollution from dust of defecation lime. For example, waste from fruit processing industries can be used as a raw material in biogas production;

waste from vegetable oil production is a raw material for animal feeding products production and etc. And that is the proper way for obtain sustainable future.

Figure-1.1. Map of Uzbekistan {1}

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1.1. Aim and objectives of the Diploma Project

Aim:

The aim of the Thesis Work “Application of defecation lime from sugar industry in Uzbekistan” is to learn modern ways of application of defecat (precipitated calcium carbonate - which is calcium containing waste of sugar industry) in different fields and suggest a suitable method or methods, which could be used in Uzbekistan to treat such type of waste and to eliminate it’s impact to environment.

Objectives:

• To present how the Joint Stock Company “Khorezm Shakar” carries out the treatment of defecation lime.

• To describe the environmental impacts of defecat.

• To describe modern ways of handling defecat in sugar producing companies in Europe, as well as methods described in the literature.

• As an example to find a company which obtains the same type of waste and describe the treatment method.

• To overview soil characters of Uzbekistan; main soil types in the region and describe different types of fertilizers used here.

• To discuss and suggest a suitable method of handling defecat in Uzbekistan considering different aspects of the region (economic, ecological, social).

1.2. Methodology of work

This thesis work was done by collecting related information, using the methods listed below:

• Interview the sugar manufactures by e-mail and by phone. To find out answers to the questions with the aim to identify the treatment methods for such type of waste, by contacting directly with the people of the field.

• Search and study related information through Internet, literature and news.

• Visit to sugar producing plants, study how they are dealing with the problem and how they are managing the same type of waste.

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1.3. Outline of the report

The report of this Diploma Project consists of 9 chapters which are aimed to satisfy the aim and objectives. Briefly content of these chapters are listed below:

1. Introduction

The chapter describes the aim and objectives of the Diploma Project, methodology of work, background and problem definition in the region and features of the defecation lime.

2. Pre study of application fields of defecation lime

In this chapter result of interviews with people from sugar industry and result of information collected through internet about application fields of defecat.

3. The study area

This chapter gives general information about Khorezm Sugar and about British Sugar Companies. Also the detailed operations of sugar production in British Sugar are described in this chapter.

4. Technological process of sugar manufacturing

In this chapter general technological process of sugar beet processing is described. This is important, because from the information given here, you can find more detailed about purification process, where in sugar production defecation lime is produced.

5. Different methods of treatment of defecation lime

This chapter describes all treatment methods of defecation lime and related information to the management of the waste.

6. Handling of defecation lime at The British Sugar

This chapter gives detailed information about handling defecat in British Sugar, advantages of its use, application amounts and technical specifications of LimeX

7. Soil character of Uzbekistan

Information about main soil types of Uzbekistan, fertility of soils and fertilizer consumption in the region are described in this chapter. Because, the main application field of defecation lime is - agriculture.

8. Discussion

All information about different handling methods of defecat is discussed for advantages and disadvantages and suitable methods for handling the waste for Khorezm Sugar Company in Uzbekistan are suggested.

9. Conclusion

In this last chapter the main conclusions from this Thesis Work are stated.

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1.4. Background

This Master Thesis “Application of defecation lime from sugar industry in Uzbekistan” in MSc Programme in Sustainable Technology is done at The Royal Institute of Technology (KTH) in Stockholm, Sweden.

This work is proposed to study the ways of handling defecation lime from sugar industry in the world and find out a suitable method or methods for Khorezm Sugar Company in Uzbekistan.

Sugar is made by some plants to store energy that they don't need straight away, rather like animals make fat. People like sugar for its sweetness and its energy so some of these plants are grown commercially to extract the sugar.

Sugar is produced in 121 countries and global production now exceeds 120 Million tons a year. Approximately 70% is produced from sugar cane, a very tall grass with big stems which is largely grown in the tropical countries. The remaining 30% is produced from sugar beet, a root crop grown mostly in the mild zones of the north and in some Asian countries.

In sugar beet processing there is a purification process, from which we have calcium containing waste named defecation lime or just defecat.

1.5. Problem definition

Khorezm region has a lot of ecological problems as other parts of the country do. Soil salinity, desertification, drink water quality, a lots of problems regarding to Aral Sea and wastes from industry.

Like in all other former Soviet Union countries until the independence in 1991, agriculture Uzbekistan was mainly focused on cotton production, which afterwards made the soils to become poor in organic matters and de-structuring.

Khorezm Sugar is the only sugar manufacturing plant in Uzbekistan.

The company obtains molasses, pulp and defecation lime as waste. These types of wastes except defecation lime had been processed in some way.

Defecation lime comes from raw juice purification process¹. In this process the company uses milk of lime and carbon dioxide. Calcium carbonate precipitates with removing non sugars from raw juice. Because of economical problems and lack of knowledge here since, this type of waste is not treated. The waste is placed in the territory of the plant, in the open air conditions.

It causes environmental problems as well. As it is dry and consists of small particles it is easy spread able with the wind. Therefore, it covers with particles of precipitated calcium carbonate nearby lands and water surface also. Furthermore, there occur land problems also, because of covering plant territory with “mountains of defecat”.

Nowadays, it is a really big problem for the region which has to be solved immediately in some way.

As all beet sugar manufacturers Khorezm Sugar Company obtains defecation lime from sugar production. The waste has not been treated since the factory is in use (see chapter 3.1). Nowadays the factory has about 80000 tonnes of defecation lime which remains on the site. The piles of waste are growing each year {1}.

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1 - Wider information about purification process and sugar manufacturing can be found in the chapter 4.

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Defecation lime has a number of influences, which cause environmental, land and health problems, such as:

• Environmental problems - because of its dryness defecation lime is easy spreadable with wind. It covers all surrounding area and water surface with the particles of the waste.

• Health problems - while spreading by wind it is dangerous for health of people living nearby and has impact on biodiversity.

• Land problems - the waste remains in the territory of the plant. It causes land problems in the area, because almost 20 % of the plant area is occupied with the mixture of waste, containing defecation lime, stones and soil from the process.

• Influence on the company’s good name. The impression of the company is also assessed with the actions done for environment.

1.5.1. About defecation lime

Defecation lime is calcium containing waste of sugar industry which uses milk of lime and carbon dioxide in the purification process. This kind of waste is called press mud, PCC (Precipitated Calcium Carbonate), filter cake, defecat and defecation lime in common². Defecat represents 8-12% to the weight of the processed beet and 5-7% of raw cane.

It contains mainly, calcium carbonate, 60-85% of the dry matter. In the dry condition, precipitated lime contains also to 10-15% of organic matter, 0.7-0.8% nitrogen, 0,2-0,9%

phosphorus’s, 0,5-1.0% of potassium. Fresh defecat holds to 60% of moisture, but after partial drying at the plant, humidity falls to 20-30% and waste remains approximately with 70% of dry substances {1}.

Defecation lime consists of the following substances: CaSO4; Ca (PO4)2; Fe (OH)2; K⁺; Na⁺; Ca⁺; NH3+; H2O; Ca (OH) 2; CaCO3; Mg; Ba; Si; S and other organic substances (nitrogen containing and non nitrogen).

The content of the waste is a very important feature because it gives a chance for determining the type of treatment. On the basis of this, one can decide what can be done with the waste, for what it’s useful and what dangerous substances it contains.

Nutrient content of defecation lime from sugar industry is not constant. It differs from time to time and country to country. It mostly depends on the content of the sugar beet too.

Chemical content of defecation lime in Khorezm Sugar is given in the table 1.1.

Table-1.1.Chemical content of defecation lime in Khorezm Sugar Company {2}

Chemical substances in defecation lime Amount

(%)

Sugar 2.0

Pectin substances 1.7

Non nitrogen organic substances 9.5 Nitrogen containing organic substances 5.9

Calcium carbonate 74.2

Lime in the form of different salts 2.8 Other mineral substances (and phosphorous acid) 3.9

Total 100.0

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2 - In this report “defecation lime” and “defecat” will be used.

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2. Pre study of application fields of defecation lime

In order to find out what is done with such type of waste in other sugar producing plants, I did some interviews with the people in this field. I contacted them by e-mail and by phone, had meetings with some of them and tried to find relevant information. In the following sub parts you can find results of analyses which I had done before making a decision.

2.1. Results of interview

At the beginning of the work I visited the Khorezm Sugar Company and talked to engineer of the factory. Defecation lime is placed in the territory of the plant and has not been treated for 9 years.

I have also been in contact with engineers, managers of the sugar manufacturing plants in the other countries. I made a list of questions, which were aimed to determine the type of treatment in their plants.

At the result of contacting sugar manufacturing companies, I have found that most of them use this type of waste as a soil amendment to stabilize soil pH and to improve soil structure. Results are given in the Appendix 1.

2.2. Information from literature and Internet

Because of difficulties in getting direct contacts with all sugar manufacturing plants and with the purpose of getting broader information and to compare them, I decided to gather information both from literature and through internet about application of defection lime.

The results of these studies are outlined in the Appendix 2.

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3. The study area

3.1. The Khorezm Sugar Company

The “Khorezm Sugar” is the only sugar producing plant in Uzbekistan. The company was launched in 1998 and its total cost amounts to US $ 83.25. Budget funds and US $ 25 million by the Turkish Eximbank financed the project. The plant is located in Yangibazar, Khazarasp district, Khorezm region.

The main product of the company is granulated sugar. The product is sold for consumption and for industry reprocessing as well.

The plant was originally designed to process 3000 tonnes of sugar beet a day which to be grown by farmers in Uzbekistan. For several years the plant’s production capacity was not fully met because sugar beet yield were at low levels. At that time, the production process needed 350.000 tonnes of sugar beet a year, but in 2000 they had refined just 96.000 tonnes.

In November 2001 the plant was reconstructed by “Shakar Investment LTD”, an Uzbek-American joint venture. That was done in order to provide the company with sugar cane during sugar beet shortage and extra seasonal period also. In this turn the Joint Venture established additional sugar refinery equipment. The company receives sugar cane from Brazil.

Present time “Khorezm Sugar” can refine and produce sugar both from sugar cane and sugar beet. Sugar beet is processed only in the months of September, October and November.

The rest of the time the company produces sugar only from raw sugar.

Currently, the company employs 920 people. Today 100 % of the production is sold on the internal market {3}.

Solid waste arises from raw material treatment (earth, plant remains), the steam generator (ash), defecation lime, molasses and sugar beet press.

Molasses, which offer 1.25 % of the raw cane processed, is used in preparation of acid, baking and nutrient yeast.

Sugar beet press (or djom), which present 25-30 % of sugar beet processed is used as a stern for animal feeding in agriculture.

Defecation lime, which present 5-7% of raw cane and 8-12% of sugar beet processed, is not used in any purposes yet.

The company produces about 10 000 tonnes of defecat per year. Since the factory is in use, defecation lime is not treated yet, and is placed in the territory of the Khorezm Sugar plant.

3.2. British Sugar Company

British Sugar is the leading supplier of sugars to the UK, providing more than half the country's sugar requirements.

Approximately 7000 farmers contract with British Sugar each year to provide around 9 million tonnes of raw material: sugar beet, which is grown on 135,000 hectares. The majority of the country's sugar beet production is concentrated in the eastern counties of England from Yorkshire down to Essex with a smaller area grown in the West Midlands. The free-draining well structured soils which are predominant in these regions are essential for successful sugar beet agriculture.

British Sugar operates six factories which produce about 1.3 million tonnes of white sugar each year from beet. The processing season, known as the 'campaign', usually lasts from September until the end of February.

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The British beet sugar industry began in the early 1900's and the first factory was built by the Dutch at Cantley in Norfolk in 1912. During the 1920's a further 17 factories were erected and until the 1930's, the crop was processed by 13 autonomous companies in 18 factories throughout the country in an unplanned and uncoordinated operation {4}.

British Sugar operates six manufacturing sites in the UK that produce about 1.3 million tonnes of white sugar each year from sugar beet. These manufacturing sites (factories) are:

1. Allscott

2. Bury St.Edmunds 3. Cantley

4. Newark 5. Wissington 6. York

All factories listed above produce LimeX (brand for defecation lime in British Sugar) from beet sugar processing. Amount of waste they get is shown in the table-3.1.

Table-3.1. LimeX production by factories (2005/06 year: estimated production/K tonnes) {5}

Factory LimeX45 LimeX70

Allscott 28 12

Bury 0 75

Cantley 55 0

Newark 0 45

Wissington 0 110

York 0 54

During my study visit to British Sugar in November, 2005 I have visited 3 factories, which are: Bury St.Edmunds, Cantley and Wissington. In the chapter-3.2.1.you will find more information about these 3 sugar manufacturing plants.

3.2.1. Bury St Edmunds sugar factory Bury St Edmunds sugar factory was built in 1925.

The factory employs a permanent workforce of 100 rising to 175 during the processing campaign which lasts, on average, about 150 days. The factory operates 24 hours a day throughout the campaign.

The factory has an installed capacity to process 12,000 tonnes of beet a day. Around 1.85 million tonnes of beet are processed every year, with more than 660 lorry loads accepted each day {6}.

The daily output of crystal sugar is about 1,300 tonnes. Sugar produced at Bury St Edmunds is stored in five silos with a combined storage capacity of 70,000 tonnes. Some of

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the beet processed is stored as thick juice in six large tanks with a combined capacity of 164,000 tonnes to be fully refined into crystal sugar during the late spring and early summer.

About 70,000 tonnes of LimeX70 is produced each campaign and sold to farmers to correct acidity, add some nutrients, and improve the structure of the soil (see figure 3.1) {6}.

3.2.2. Cantley sugar factory

Cantley sugar factory has a special place in the history of this country's sugar industry.

Built in 1912, it was the first British beet sugar factory.

Cantley factory employs a permanent workforce of 110 rising to 155 during the processing campaign which lasts, on average, about 140 days. The factory operates 24 hours a day throughout the campaign.

The factory processes in excess of 1.3 million tonnes of beet every year. On average 380 lorry loads are accepted each day. The factory can process up to 9,000 tonnes of beet a day, with an average daily throughput of 8,500 tonnes.

Around 1,150 tonnes of crystal sugar are produced every day. Sugar is stored in six silos, each with a storage capacity of 10,000 tonnes. Some of the beet processed is stored as thick juice in large tanks with a combined capacity of 44,000 tonnes to be fully refined into crystal sugar during the late spring and early summer {6}.

In addition granulated sugar mainly in sacks, caster and extra fine sugar is also supplied from this factory.

LimeX45 is produced each campaign and sold to farmers to correct acidity, add nutrients and improve the structure of the soil (see figure 3.2)

Figure-3.1.LimeX70 products storage at The Bury St Edmunds Sugar Factory (Pictures taken by Shoira Masharipova)

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3.2.3. Wissington sugar factory

Wissington sugar factory was built in 1925. The factory has a permanent workforce of approximately 150 rising to 330 during the processing campaign which lasts, on average, about 22 weeks. This is followed by a juice refining operation which lasts a further 22 weeks.

The factory operates 24 hours a day throughout the campaign and juice refining period.

Approximately 2.4 million tonnes of beet are processed every year. Up to 900 lorry loads are accepted each day and the factory is able to process excess of 16,000 tonnes of beet a day.

Wissington is the largest of the company’s factories with a daily output of crystal sugar reaching up to 1,500 tonnes. Sugar produced at Wissington is stored in seven silos with a combined storage capacity of 97,000 tonnes. Some of the beet processed is stored as thick juice in ten large tanks, to be fully refined into crystal sugar during the late spring and early summer.

White crystal sugar is dispatched from the factory in bulk road tankers, 25 kg and 1 tonne bags. In addition, Wissington factory distributes a range of liquid sugars.

Over 100,000 tonnes of LimeX70 is produced each campaign and sold to farmers to correct acidity, add some nutrients, and improve the structure of the soil (see figure 3.3) {6}.

Figure-3.3.Pressed LimeX70 and its storage in The Wissington Sugar Factory (Pictures taken by Shoira Masharipova)

Figure-3.2.Newly pumped and stored LimeX45 products in Cantley Sugar Factory (Pictures taken by Shoira Masharipova)

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Fig.3.4. Beet receiving {6}

Fig.3.5. Beet washing {6}

Fig.3.6. Slicing machine {6}

Fig.3.7. Diffusion {6}

3.2.4. Technological operations in British Sugar Factories

Located in East England, the North-East and the East and West Midlands, six state-of- the-art processing plants match anything in the oil, chemical and power industries for complexity. Together, they process around 9 million tonnes of sugar beet during each production campaign. They produce 1.3 million tonnes of sugar per year. They satisfy more than half the UK's sugar requirements and supply export markets.

The extraction and production of white sugar from beet takes place on the same factory site. Beet Sugar manufacturing process of sugar and explanations of process stages in UK are described below (sugar manufacturing process scheme in British Sugar you can find in the Appendix-3).

Each year's crop yields between eight and ten million tonnes of sugar beet. Around 3,500 lorry loads of sugar beet are delivered daily to British Sugar's factories which take in more than 400,000 tonnes of beet each week during the processing season (campaign); this is completed by the end of February.

Sampling

On arrival, a sample of the sugar beet is taken from the load and tested to measure the sugar content and to determine the amount of soil, tops or leaves present in the load. These analyses, combined with the weight of the vehicle entering and leaving the factory, enables the calculation of the quantity of sugar delivered and hence the payment due (Fig.3.4.).

Cleaning

Sugar beet floats in water and in the cleaning stage of the process it is moved around in large quantities of water, allowing the beet to pass through machinery which 'catches' stones but allows the beet to float over the top. Weeds and other trash are also removed before the beet enters the factory, where it is sliced into thin slices called 'cossettes' (Fig.3.5.).

Slicing

The slicing machines work in a similar manner to a kitchen grater and the cossettes they produce have a 'V' cross section. This ensures the largest possible surface area is

presented to maximise the sugar extraction stage (Fig.3.6.).

Diffusion

Sugar is extracted from the beet by diffusion. This process takes place in a large vessel and in simple terms is akin to brewing tea in a teapot. The cossettes are mixed with hot water at around 70°C for a period of time and the sugar simply passes from the plant cells into the surrounding water by the diffusion process (Fig.3.7.).

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Fig.3.8. Filters (Picture taken by Shoira Masharipova)

The vegetable material left behind from this stage is mechanically pressed to extract as much remaining sugar and water as possible and, after the addition of molasses, is dried to produce animal feed products. It is this drying process which gives rise to the familiar plume of steam rising from the factory. The liquid resulting from the diffusion process is dark in colour and is called raw juice.

Purification

This juice is passed through an important purification stage called carbonation. This involves mixing the juice with milk of lime and adding carbon dioxide gas. During this process, the carbon dioxide and the milk of lime re-combine to produce calcium carbonate which precipitates out, taking most of the impurities from the juice with it. This lime which contains important trace elements is sold as a soil improving agent under the LimeX brand.

Evaporation

The pale yellow juice which remains is called thin juice and while much purer it is still relatively low in sugar content. It passes to the next stage of the process - evaporation - where the water is boiled off in a series of evaporator vessels to increase the solids content of the juice from the previous 16 per cent in thin juice to 65 per cent in the thick juice.

The concentrated juice passes through filters (Fig.3.8.), after which it is ready for the final stage of the process; or it can be stored and brought back into the factory during the summer to produce crystal sugar.

Crystallisation

The crystallisation process takes place in vacuum pans which boil the juice at lower temperatures under vacuum. When the juice reaches a predetermined concentration it is 'seeded' with tiny sugar crystals which provide the nucleus for larger crystals to form and grow.

When the crystals reach the desired size the process is stopped and the resultant mixture of crystal sugar and syrup - known as massecuite - is spun in centrifuges to separate the sugar from the 'mother liquor'. The sugar crystals are washed and after drying and cooling, are conveyed to storage silos.

Some sugar remains in the separated liquid so it is boiled again in a further set of vacuum pans to produce raw sugar. This process is repeated a third time resulting in final product sugar and molasses. Raw and final product sugars are re dissolved into the thick juice.

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Figure.4.1. Sugar beet yield (Picture taken by Shoira Masharipova)

Figure.4.2. Photosynthesis {8}

4. Technological process of sugar manufacturing

Sugar is a form of simple carbohydrates, which supplies as a best energy for human body. In the family of simple sugar lie three main forms of sugar known as glucose, fructose and sucrose. Sucrose when consumed will be broken down by human bodies into glucose and fructose. Sucrose is the most common form of sugar found in our diet.

Sugar is found almost in every fruit and vegetable. In a balanced diet that consists of protein, carbohydrate, fibre and fats, carbohydrate remains the most important sources of our energy. While the digestion and conversion of complex carbohydrate (such as rice, potato etc) into glucose by our bodies requires a longer time, simple sugar such as a piece candy or a cup of beverage would help if we need a quick support of energy.

Sugar is made by some plants to store energy that they don't need straight away, rather like animals make fat. People like sugar for its sweetness and its energy so some of these plants are grown commercially to extract the sugar.

Sugar is produced in 121 countries and global production now exceeds 120 million tons /year. Approximately 70% is produced from sugar cane, a tall grass with big stems which is largely grown in the tropical countries. The remaining 30% is produced from sugar beet, a root crop grown mostly in the mild zones of the north and in some Asian countries {7}.

In sugar beet processing there is a purification process, from which we obtain calcium containing waste, which is called defecation lime or just defecat. As it is the waste only from sugar beet processing, in my thesis work I will describe sugar producing process from sugar beets.

4.1. Raw material – sugar beet futures

Sugar beet is a temperate climate biennial root crop (fig.4.1). It produces sugar during the first year of growth in order to see it over the winter and then flowers and seeds in the second year. It is therefore sown in spring and harvested in the first autumn/early winter for industrial use. In the photosynthesis process, CO2 of the atmosphere and the soil moisture with the help of sunlight form the sugars (carbohydrates) (fig.4.2):

The beet stores the sucrose in the bulbous root.

Typical sugar content for fully grown beets is 17% by weight but the value depends on the variety and it does vary from year to year and location to location. This is substantially more than the sucrose content of mature cane but the yields of beet per hectare are much lower than for cane so that the expected sugar production is only about 7 tons per hectare while sugar cane is 100 tons per hectare {7}.

6H₂O + 6CO2 C₆H₁₂O₆+ 6O₂

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Figure-4.3. Sugar beet content {9}

The sugar beet contains 14-17% sugar, 76-78% water, 4-5% insoluble dry ingredients, and 2-3% soluble dry ingredients (nitrogenous and non-nitrogenous organic and inorganic components (figure-4.3.) {9}.

4.2. Technological process of beet sugar producing

Processing of sugar beet into granulated sugar consists of a chain of physical and chemical operations with the object being to preserve the natural sugar and remove all other materials (in the Appendix-4 you can see flow chart of sugar beet).

The total time from beet washing to white sugar is about twelve hours. Depending upon sugar content of the beet, 100 tonnes of beet will give approximately 12-14 tonnes of sugar and 3-4 tonnes of molasses {11}.

White crystal sugar production involves a great many processing stages, such as:

1. Harvesting 2. Beet Handling 3. Diffusion 4. Pulp Dryer 5. Lime Kiln

6. Purification & Filtration 7. Evaporation

8. Crystallization & Separation 9. Molasses desugarization 10. Packaging and Storage

There follows descriptions of the main unit operations of the beet sugar production.

4.2.1. Harvesting the beet

The harvesting of the sugar beet starts about at the end of September and continues for about 2-3 months. Production of sugar from the beet is a continuous process. Once the campaign starts it continues 24 hours a day, seven days a week, until the entire beet is processed. Harvesting is also done by mechanical ways. Today's mechanical harvester is particularly original. It not alone takes the root out of the ground; it also cleans it and cuts off the top of the plants. The leaves are a valuable source of animal feed.

Sugar beets are usually transported to the factory by large trucks.

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Figure-4.4. Beet handling {10}

4.2.2. Beet handling

Beet handling (figure-4.4.) in the factory includes weighting, sampling and unloading.

The Lorries drive over a weighbridge where their weight is automatically measured. At the same time a sample of the particular load is taken to determine the sugar percentage and the amount of tare in the overall load. Tare may consist of clay, stones, beet tops, etc. It is deducted from the gross weight of the load in order to determine the net weight of clean beet delivered. The farmer is paid a predetermined price per tonne of clean beet delivered. There are two systems of unloading - dry unloading and wet unloading. When dry unloading, the beet is conveyed from the lorry by a series of conveyer belts to open air silos where it is stored. In wet unloading the beet is washed from the lorry by means of a powerful jet of water. Beet is transferred from the silos to the factory by means of water. In route to the production process, stones and grass are removed in a series of stone and grass catchers.

The beet is thoroughly washed before processing to remove all traces of clay and sand.

The beets then flow into a beet washer where they are rubbed together to be cleaned. From the washer, they are elevated to the top of the factory where a final rinsing and de-watering takes place on a roller-spray table. The beets are then conveyed into a hopper where they are fed into the beet slices.

4.2.3. Diffusion process

The actual sugar is inside the beet and has to be extracted. The sugar beets are fed from the slicing hopper into the slicing machines where very sharp knives cut them into long noodle-like pieces called cossettes. Emerging from the slicing machines, the cossettes fall onto a conveyor belt to be weighed and fed into the diffusion system. Here the sugar is removed from the beets by hot water "washing" or diffusing the sugar from the beets. Sugar is then extracted from the beet by diffusing it out with hot water up to 70^oC. This is done in a large vessel specially designed for this purpose (figure-4.5.).

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Figure-4.5.Diffusion process {10}

Beet slices are fed in continuously at one end and hot water at the other end. The beets are fed into the bottom of the diffuser and are moved upward through the diffuser where they emerge with 2% of the sugar left in them. The spent beets are called wet pulp and processed in presses and dryers to become livestock feed. Hot water is fed into the top of the diffuser and flows down through the beets continuously extracting the sugar from the beets and emerges from the diffuser as sugar water called "raw juice". This contains about 14% sugar and is black in colour. The extraction process uses a process called osmosis where the sugar is passed through the porous membrane on the beet's cell wall, while some of the non-sugars are retained by the cell.

4.2.4. Pulp Dryer

The wet pulp (90-92% water) from the diffuser is sent to pulp presses. The pulp presses squeeze the pulp in order to remove as much water as possible. And then it is called pressed pulp (72-78% water) and is either sold as livestock feed or sent to the dryer for further processing. The water pressed out of the pulp is sent back to the diffuser to recover the sugar in it. The rotary drum pulp dryers are direct fired by oil, gas or coal and dry the pulp to 12%

moisture (figure-4.6.). The dried pulp can be sold but is normally compacted into pellets for easier handling and stored in a bulk warehouse for future sales. Pressed pulp is sold for short- term use while pellets store for longer periods, but both are used for livestock feed.

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Figure-4.6.Pulp dryer {10}

4.2.5. Lime Kiln

In sugar factory the lime kiln (figure-4.7.) supplies the burned lime and carbon dioxide for the purification processes. Limestone (calcium carbonate) is heated to 1093⁰C in a vertical shaft lime kiln using hard coal or natural gas. The heating process releases carbon dioxide from the limestone reducing the calcium carbonate to calcium oxide. The calcium oxide (burned lime) is then mixed with sweet water to form milk of lime in a lime slacker. The milk of lime is mixed with the juices in the purification system and the carbon dioxide is pumped directly to the purification system.

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Figure-4.7.Lime Kiln {10}

4.2.6. Purification and Filtration processes

At the diffusion stage other substances are extracted from the beet as well as the sugar.

But before sugar can be produced in a white crystalline form it is necessary to remove as many of these non-sugars as possible. This part of the process is referred to as juice purification.

The main raw materials used in the purification are lime and carbon dioxide gas which are got by burning limestone in a kiln. These substances are added to the juice causing non- sugars to be precipitated out of the solution.

The raw juice moves through various stages of purification and filtration (figure-4.8.) to remove non-sugars. It is first heated to 85^o C and then sent to the pre liming, where most of the non-sugars are precipitated by gradual pH elevation (progressive pre liming). From pre liming, the juice flows through the main liming where the rest of the lime is added on its way to the first carbonation station.

Here carbon dioxide gas from the lime kiln is bubbled through the limed juice where it reacts with the lime to form calcium carbonate and adsorbs some of the non-sugars. This process is tightly controlled to give the juice the proper pH or alkalinity leaving the first carbonation station.

Now the carbonated juice flows to a clarifier where the precipitated calcium carbonate formed in first carbonation is settled out. This leaves a clear juice to be sent to heaters and on to the second carbonation system. The defecation lime left behind in the bottom of the

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Figure-4.8.Purification and filtration {10}

left in it. The washed defecat has about 1% of the sugar from the beets in it and is sent to a lime pond. The washed water with the recovered sugar is called "sweet water" and is sent to the lime house to be mixed with the burned lime to be recycled to the purification system.

In the second carbonation system, carbon dioxide gas is again bubbled through the juice reacting with the residual lime to form calcium carbonate precipitate. The amount of gas is controlled by pH to obtain the proper alkalinity and the carbonated juice is sent to the second carbonation filters where the calcium carbonate precipitate is removed. This precipitate is sent to the defecat tank and then to the drum filters for processing with the precipitate from first carbonation. The clear juice moves on to sulphuring where sulphur dioxide is added to the juice to remove some colour forming materials that would carry through to the finished sugar and to adjust the pH to allow for easier boiling in the evaporators and vacuum pans in further processing.

4.2.7. Evaporation process

The purified juice is a sugar solution containing approximately 14% sugar and 1%

non-sugars. In order to turn the sugar into a crystalline form it is necessary to concentrate this solution. This is done by boiling off water from the solution in large vessels known as evaporators (figure-4.9.). The sulphated juice is now called "thin juice" and is heated and fed into the evaporators. The evaporation station consists of 4 to 6 evaporator bodies that contain tubes. Steam is fed to the outside of the tubes and the juice is on the inside of the tubes. The heat transfers from the steam to the juice. This evaporates some water from the juice helping to concentrate it while the steam is condensed. The water evaporated in one evaporator becomes the steam feeding the next evaporator while the juice travels from one effect to the next. The thin juice enters the evaporators at 13 to 15% solids and leaves the station at 60%

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Figure-4.9. Evaporation process {10}

solids and is called thick juice. The multiple effect station allows 2.5 to 2.8 pounds of water to be evaporated per every pound of steam fed to the first effect of the evaporator station.

4.2.8. Crystallization and Separation

The thick juice from the evaporator station is sent to the high melting machine where the high and low raw sugars are dissolved in it through vigorous agitation and heat. The melted juice is then heated and filtered and further concentrated through the "concentrator" to 70 to 75% solids. This is then called standard liquor and is fed to the white pan where white sugar is crystallized from solution. Crystallization takes place in a batch process when water is evaporated from the solution in the vacuum pan. Finely ground sugar is used to "seed" the pan and each seed crystal grows into a typically sized sugar crystal. More and more water is evaporated forcing more and more sugar to crystallize on each sugar crystal. The solution is concentrated to 92% solids and consists of sugar crystal surrounded by syrup of sugar-water and this is call white massecuite. The massecuite batch is dropped into a mixer that then feeds the white centrifugals.

The white centrifugals separate the sugar crystals from the syrup in the massecuite by spinning the sugar against a screen while the syrup spins through the screen. Hot water is used to wash the residual syrup from the crystal and the spinning helps to partially dry the sugar.

The white sugar is then conveyed to the granulator for further drying and cooling.

The finished sugar is then sifted for lumps and moved on to the bulk sugar bins for storage. The bulk storage "conditions" the sugar before it is loaded for bulk shipment or sent to the warehouse for packaging.

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Figure-4.10.Crystallization and Separation {10}

The white centrifugal produce two syrups, the high wash is higher purity syrup that is recycled to the high melter. The green is the lower purity syrup from the white centrifugals and it still contains a considerable amount of sugar. It is sent to the high raw vacuum pan for processing. Here again, seed crystals and evaporation are used to remove sugar from the syrup solution and deposit it on the sugar crystal. The high raw massecuite (sugar crystal and sugar syrup mixture) is sent to a mixer and then to another set of centrifugals to separate the sugar crystal from the syrup (figure-4.10.). The sugar crystals made here are not a good enough quality to sell as white sugar (they look like raw sugar) so they are sent to the high melter to be re-dissolved and re-processed in the white pan. This pan, mixer and centrifugal system are called the high raw system.

The syrup leaving the high raw centrifugals is called machine syrup. It is an even lower purity than the high green syrup but still contains enough sugar that it needs for further processing. The machine syrup is sent to the low raw system that contains one additional piece of equipment as compared to the high raw system. The low raw vacuum pan is used to crystallize sugar out of solution but instead of feeding the low raw massecuite straight to the low raw mixer and centrifugals, the low raw massecuite is sent to a crystallizer where cold water is used to continue the crystallization process for an additional 48 hours. From here it is sent to a reheating and to the low raw centrifugals where sugar crystals are separated from the syrup called molasses. The sugar crystals are sent to the high melting for re-processing in the white pan. The molasses is about 50% sugar by weight and this is sent to the Scottsbluff facility where about 80% of this sugar is recovered. The molasses is another place in the

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Figure-4.11.Molasses desugarization {10}

process where sugar is lost. About 10-15% of the sugar from the beets leaves the sugar factory in molasses. This is the biggest loss of sugar in a standard sugar factory.

4.2.9. Molasses desugarization process

The molasses is sent to the molasses desugarization system (figure-4.11). This operation removes about 80% of the sugar in the molasses. The molasses must be treated to remove some non-sugars that will cause processing problems in the separation process. These non-sugars consist of calcium, magnesium and suspended solids. The molasses is softened by replacing non-sugars with sodium and filtering the precipitates formed in the reaction. The pre-treatment process consists of dilution, heating, soda ash addition (sodium source), reactors (softeners) and filtering. The filtering process uses plate and frame filters to squeeze the softened molasses through filter leaves, while the precipitated non-sugars remain behind.

The softened molasses is sent to the separation (ion exclusion) process. The columns are loaded with a resin that attracts certain chemicals while letting other chemicals pass through quickly. This difference in travel time is used to separate the molasses into a sugar fraction, a betaine fraction and a residual molasses fraction. The fractions are then concentrated and the sugar fraction is stored for processing in the sugar end of the Scottsbluff factory into white sugar while the betaine and molasses fractions are sold as by-products.

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4.2.10. Packaging and Storage of product

The final sugar is white and ready for use, whether in the kitchen or by an industrial user such as a soft drink manufacturer.

Dry sugar is stored in sugar silo which has air conditioning, so the sugar can be kept for a longer time. For the expedition sugar is packed in 50, 25 kg bags, or a commercial packing in 1 kg and 2 kg bags. It can also be delivered unpacked in tanks. Before packing, it is important that all sugar be cooled below 45° C (113° F). At higher temperatures it hardens in the bag or silo and can develop colour. Beet sugar factories store white sugar in silos during production and pack sugar year-round to meet the current market {10}.

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5. Different fields of application for defecation lime

Defecation lime from sugar industry can be handled in a different ways according to conditions in the area, like:

1. Distance from plant to the handling station.

2. Soil conditions (pH, fertilizer need, types of crops to be grown, etc.).

3. Need for such type of “secondary raw material”.

4. Regulations in economical, social and ecological field of the region.

Defecation lime from purification process is treated in different ways in the different countries of the world. Possible methods of handling defecat are listed below:

1. Liming material as soil pH stabilizer and improver;

2. As fertilizer;

3. Component of mixed greenhouse soil;

4. Sorbent, to treat waste water from other branches of industry;

5. Additional material in cement production;

6. In foam concrete production

7. Additional minerals for animal feeding and others.

As a result of interviewing some sugar manufacturing plants it was shown that almost all countries use it as a soil amendment to stabilize soil pH and to improve soil structure. But, there should be certain conditions of the soil to handle it in such way such as described in the chapter 7.

5.1. Defecat for stabilizing soil pH

Defecation lime from sugar industry is an important complementary nutrient source (for more information about ingredients see the chapter-1.5.1.). To the quality of root-crops, for example to the productivity of sugar beet significantly influences the pH of soil solution.

Its optimum value, depending on soil types varies in the range of 6.0-7.0. On the loamy soils favourable pH reaction is from neutral to weak-alkaline. For the light soils weakly acid reaction is acceptable.

An increased acidity represses plants and vital activity of soil micro organisms and encourages the development of diseases.

Therefore all soils which have pH value of < 5.5 need liming. Defecation lime, which contains 40-70% of carbonate calcium, 10-15% of organic matter, 0.3-0.8% of nitrogen, 0.2- 1% of phosphorus and 0.4-0.8% of potassium is quite good amendment in this case{12}.

5.1.1. Soil pH

Soil pH, or soil reaction, is an indicator of the acidity or alkalinity of soil and is measured in pH units. The pH scale goes from 0 to 14 with pH 7 as the neutral point. Soil pH affects the solubility of minerals or nutrients essential for plant growth. Soils with 4.0-5.0 pH value are strongly acid. They can have high concentrations of soluble aluminium, iron and manganese, which may be toxic to the growth of some plants.

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Soils are become acidic as a result of:

• Rainwater leaching away basic ions - calcium, magnesium, potassium and sodium;

• Carbon dioxide from decomposing organic matter and rain water forming weak organic acids;

• Decay of organic matter and ammonium and sulphide fertilizers.

Descriptive terms associated with certain ranges in soil pH are shown in the table-5.1.

Table-5.1. pH ranges {13}

Acidity(alkalinity) conditions

pH values Examples

Extremely acid less than 4.5 Lemon = 2.5

Very strongly acid 4.5 – 5 tomatoes=4.5

Strongly acid 5.1 – 5.5 cabbage=5.3

Moderately acid 5.6 – 6.0 potatoes=5.6

Slightly acid 6.1 – 6.5 Cow’s milk – 6.5

Neutral 6.6 – 7.3 blood=7.3

Slightly alkaline 7.4 – 7.8 Eggs = 7.6 – 7.8

Moderately alkaline 7.9 – 8.4 Sea water = 8.2 Strongly alkaline 8.5 - 9

Very strongly alkaline > 9.1 Lime=12 5.1.2. Liming

Acid soils are unfavourable for most plants. The acidity of soils to different degree is dangerous for the plants. It suppresses them and stops normal increase and development.

There are plants which grow better on soils of slightly acid and even neutral pH. The majority of garden plants do better on the middle soils. Acidity of the soil affects plants not only directly, but also indirectly. Acid soils do not dry in spring and then in summer time rapidly dry up and are covered by crust. The nutrients contained in the acid soils, are badly managed by plants. In such soils the substantial part of some introduced fertilizers (for example, phosphoric) is converted to the inassimilable form. Acidification of soil is accompanied, furthermore, by the accumulation of substances which are harmful for the plants. In the acid soils the bacteria will also develop badly.

Liming is better done in the period of preparation of the soil, but it is also possible after this period. In sections occupied with fruit and berry plants, it is possible to introduce lime at any time, but in sections for wild strawberries, lime must be introduced only after plants finally strike root not earlier than 2 months after sawing, which will give an increase yield. Lime is added in spring or in autumn before the deep working of soil.

For liming the soil a lot of substances can be used. Mostly, ground limestone is used.

This is the basic lime fertilizer. Besides it, other lime containing substances are possible to use. These are: slaked lime, ground dolomites, ground chalk, lake lime, dolomite flour and diverse wastes of the industry: defecation lime from sugar industry, cement mill, burned dolomite dust, gas lime, carbide lime, peat ashes and many others {14}.

On the soils with the increased acidity lime added at the higher doses. The doses of lime introduced depend on a number of conditions: from the acidity of soil and its mechanical