Handbook on Bio Gas and Its Applications

Best Sellers

Handbook on Bio Gas and Its Applications

Author: NIIR Board
Format: Paperback
ISBN: 8186623825
Code: NI114
Pages: 454
Price: Rs. 975.00   US$ 100.00

Published: 2004
Publisher: National Institute of Industrial Research
Usually ships within 3 days



Add to Cart

Recommend to Friend

Download as PDF

Bookmark and Share



Bio Gas typically refers to a gas produced by the biological breakdown of organic matter in the absence of oxygen. Organic waste such as dead plant and animal material, animal dung, and kitchen waste can be converted into a gaseous fuel called Bio Gas. Bio Gas is basically a mixture of methane and carbon dioxide; it originates from biogenic material and is a type of bio fuel. It is a low cost form of energy derived from renewable waste resources: animal manures, agricultural residues, industrial wastewater, human waste and other organic materials. Bio Gas has been used widely as a source of energy and waste treatment, and as liquid fertiliser for soil enhancement, since long time. Digestion the underlying biological process of Bio Gas technology leads to a renewable energy service that ensures a distributed energy production, in which the energy is produced at the point of consumption or demand. A Bio Gas digester, which produces the Bio Gas, also provides an excellent agricultural waste management solution, most notably animal manures. Also, capturing methane generated in a Bio Gas digester has an immensely important role to play with respect to rural energisation, poverty alleviation and development, increased industrial and agricultural efficiency and competitiveness, and improved management of our greenhouse gas emissions. The major applications of Bio Gas are as fertilizer, fuel gas, methane production, mechanical and electrical power production, diesel engine operation, etc. Bio Gas technology is one of the fastest growing renewable energy sectors worldwide, with the annual market growth exceeding 30% each year.
This book majorly deals with Bio Gas plants, raw materials for Bio Gas generation, utilization of Bio Gas and slurry, engineering design of Bio Gas units for developing countries, engineering aspects of small scale Bio Gas plants, a village scale Bio Gas pilot plant study using high rate digester technology, structural behaviour and stress conditions of fixed dome, simplified anaerobic digesters for animal waste, mechanical and electrical power from Bio Gas in developing countries, fuel gas production from organic wastes by low capital cost batch digestion, the toxicity effect of pesticides and herbicides on the anaerobic digestion process, the toxicity effect of pesticides and herbicides on the anaerobic digestion process, Bio Gas manure as a complete fertilizer, feasibility for Egyptian farmers etc.
The book contains technology of Bio Gas generation with its applications. This book will be an invaluable resource for researchers, consultants, entrepreneurs, institutional libraries, students etc.

^ Top

Related Books


Contents

Hide Down
1. Biogas Plants: A Boon For Rural Family
Composition of biogas and slurry
Composition of slurry
Raw materials for biogas generation
Types of biogas plants
KVIC floating drum type
Janata biogas plant
Deenbandhu biogas plant
Shramik Bandhu biogas plant
Selection of size of biogas plant
Selection of type of biogas plant
Factors to be considered
Technical considerations
Consideration of Climatological factors
Consideration of Geographical factors
Economic considerations
Utilization of biogas and slurry
(a) Utilization of biogas
(b) Biogas burners
(c) Chapatti burner
(d) Biogas lamps
(e) Utilization of slurry as manure
Compostion of slurry
Wet slurry
Dried slurry
Other uses of slurry
In Pisciculture
In Mushroom production
Advantages
Limitations
2. Engineering design of biogas units for developing countries
Design concepts used for floating cover Indian styledigesters
Design concepts used for a Chinese digester
Design concepts used for a bag digester
Items to consider in examining a system
Operational factors
Composition of the organic feed-stock
Retention times
Concentrations of the feed-stocks
Organic loading rate
Degree of mixing
Heating and heat balance
Location of a digester system
Slurry effluents
Construction materials
Sizing of the digester
Size based on health criteria
Size based on production of soil conditioner
Size based on energy
Design example
case 1 : fresh manurea and urine
case 2 : manure and concrete pad not collected daily
case 3 : manure on the ground, partially dried
case 4 : using destruction of volatile solids
case 5 : design using ESCAP (Indian) approach
case 5 A : fresh manure adn urine
case 5 B : manure from a concreate pad
case 5 C : manure on dirt
Construction costs
Conclusions
3. Engineering Aspects of small-scale biogas plants
Structural demands
Relation between the length and height of the bearing structure
Size of the Digester
Size of gasholder
Gasholder-digester ratio
30 days retention time (RT)
60 days RT
90 days RT
120 days RT
Engineering for extension programs
Concluding remarks
4. An improved plug-flow design for the anaerobic digestion
  of dairy cattle waste
Introduction
Methodology
Description of the plant
Mixing and feeding tank
Anaerobic digester
Biogas piping and storage
Digester heating station
Capital costs
Results and discussion
Conclusions
5. A village scale biogas pilot plant study using high rate digester technology
Digester
Insulation of digester and gas-holder
Slurry heating system
Operation of plant and presentation of data
Discussions of results
Conclusions
6. Compost-heated small scale farm digester appropriate for Korean conditions
System design and construction
Biogas generation from pig manure
Results and discussion
Oraganic material loading conditions
Maintaining high temperature by compost heat
Heat loss comparison
Economic feasibility
7. Structural behaviour and stress conditions of fixed dome
  type of biogas units
Base of fermentation tank
Wall of fermentation tank
Dome of gas-holder
Construction technique
Analytical considerations
Structural testing of biogas unit
Concluding remarks
8. Ferrocement gasholder for two 60 M3 diester
Procedures for construction of a 20 M3 gasholder
(1) Construction of the mould
(2) Reinforecment
(3) Plastering
(4) Gas-tightness
(5) Inner-steel structure
Conclusions

9. Simplified anaerobic digesters for animal waste
Batch digester plant Results
Plug flow digester plant Results
Covered lagoon biogas system Results
Continious expansion digester
Tests on a small electric generator set fuelled by biogas
Results
An economic evaluation of the plants
Conclusions
10. Cold condition biogas
Methodology
Results and discussion
11. Mechanical and electrical power from biogas in developing countries
Engines modification for bio-gas use
Performance of biogas fuelled engines
Main factors limiting use of biogas fuelled engines and prospective solutions
12. Performance of a small diesel engine operating in a dual fuel mode with biogas
Objectives of the research
The test unit
Fuels used
Test procedure
Evaluation of the test results
Discussion of the test results
Power out-put
Exhaust gas temperature and combustion
Specific fuel consumption and fuel savings
Efficiency
Comparision of mixing chamber types
Conclusions and recommendations
13. Methane production from farm wastes
History of application of farm digesters
Post World War II developments
Post 1970 developments
American farm digesters
Technical problem
Economic feasibility of farm waste digestion
Barriers to application of anaerobic digestion to farm wastes
Technical approaches to system improvements
Research needs
14. Optimization of bio-conversion of solid and liquid residues
Technological aspects
1. Parallel operation
2. Series (stages) operation
3. Phased operation
Advantages of phased operation
Fixed film and suspended growth reactors
1. Fixed bed
2. Expanded bed
3. Fluidized bed
4. Anaerobic rotating discs
5. Recycled bed
A. Contact or recycled flocs
B. Fluidized flocs or sludge blanket
C. The digestor
Choice of process and reactor type
Micro-organisms
Bio-chemical study of the process
1.Screcning of the Eectron Transfer proteins and Enzymes
2.Purification Processes.
Bacterial control of the digester through co-factor analysis.
15. Novel process for high-efficiency bio-digestion of particulate feeds
Limitations of concentional anaerobic digestion
Novel process concepts
Phase seperation
High-SRT Digesters
Two-phase digestion of semi solid feeds
Studies with CSTR Digesters
Studies with upflow digesters
Dominant reactions in first and second stage digesters
Advantages of two-phase fermentation mode and the upflow digester
Energetic and economic advantages of two-phase digestion
Two-phase digestion of solid feeds
Summary and conclusions
16.Biogas from organic waste diluted with seawater
Materials and methods
The organic waste
The synthetic seawater
The Inoculum
The digestion appartus
Experimental procedure
Analytical procedures
Methane content
Results and discussion
Conclusion
17. Fuel gas production from organic wastes by low capital cost batch digestion
Background on "controlled" landfilling
Process description
Conventional landfill gas recovery
Application of enhancement to agricultural residues
Status of landfills as fuel gas sources in the United States
18. Biogas production from water Hyacinth (Eichhornia crassipes) : Influence of temperature
Materials and methods
Fermenter
Substrate
Inoculum
Analytical Methods
Experimental procedure
Results and discussion
19. The toxicity effect of pesticides and herbicides on the anaerobic digestion process
Materials and methods
Results and discussions
Effects of Lindane and DDT on anaerobic digestion of mixtures of cotton stalks and cow-dung.
Effect of Gesapax and Gesaprime on the anaerobic digestion
of mixture of water Hyacinth and fresh cow-dung.
Effect of Gesapax and Gesaprime on the anaerobic digestion
Of mixture of weeds and fresh cow-dung.
Conclusion
20. Biogas production from some organic wastes
Materials and methods
Organic wastes
Geranium flour
Akalona
Watermelon residues Citrullus Vulgaris
Starter
Digestion apartus
Analytical procedures
Gas volume
Methane content of the biogas
Determinations of total solids
Experimental
Results and discussion
Biogas from geranium flour (gf)
Biogas production from Akalona (Ak)
Biogas production from Watermelon residue (WR)
21. The assessment of Cellulytic activities in anaerobic digesters by the"TextilCouponTechnique"
The use of the screw-capped tubes
The crimped-caped-serum tubes
Results and discussion
Discussion
22. Biogas production from antibiotic-contaminated cow manure
Materials and methods
Experimental procedure
Results
Discussion
23. Biogas from liquid agro-industrial wastes derived from Banana and Coffee processing
Results
24. A simple, rapid and accurate method for determination of Carbon-di-oxide in Biogas
Background
Theory
Material
Procedure
Estimation of Methane content
Validation
25. Assessment of anaerobically digested slurry as a fertilizer and soil conditioner
Fertilization effect on effluents on field-grown Wheat in clay soil
Microbiological and chemical analysis
Result
Composition of effluents from bio-gas plants
Introduction
Methodology
Effluents sources
Detection of phytotoxicity
Methods of handling effluents
Fertilization effect of effluents on corn (pot experiment)
Fertilization effect of effluents on wheat (pot experiment)
Effect of continuous feeding on effluent composition
Phytotoxic effect of digester effluent
Changes in fertilizer value of digester effluents during handlling and storage.
Effluents as soil conditioner
Fertilizer value of the digester effluents
Effect on nutrient uptake
Yield response to fertilizer application
Discussion
26. Repeated application of anaerobically digested slurry and its effect on the yeld and NPK uptake of Wheat, Turnips and Onion plants
Methodology
Materials
Experimental
Chemical analysis
Results and discussion
Effect on the dry matter yield
Wheat plant
Turnip plant
Onion plant
Effect on Nitrogen, Phosphorus and Potassium uptake
27. Biogas manure as a complete fertilizer, feasibility for Egyptian farmers
Composition of bio-gas manure and treatments
Aim and scope of work
Results and discussion
Short term effect of biogas manure
Maize
Wheat
Rice
Broad bean
Cotton
Spinach
Carrots
The residual effect of bio-gas manure
Residual effect of bio-gas manure on Wheat
Residual effect of bio-gas manure on Broad bean
28. Health risks associated with the use of biogas slurry: an introductory note
29. Incidence, persistence and control of parasitic eggs and Cysts in anaerobically digested wastes
Mehodology
1.Incidence of Ascaris eggs and Eimeria Oocysts in different
village digester.
2. Laboratory-controlled experiments
Aeration of the sludge after 45 days
Results and discussion
1. Incidence of Ascaris eggs and Eimeria Oocysts in different
village digester
2. Laboratory-controlled experiments
Conclusion
Incidence, persistence and control of some pathogens during anaerobic digestion of organic wastes
Methodology
Isolation and identification of the pathogens
Results
Isolation of pathogens in samples obtained from different operating village digester.
Persistence and control of pathogens during anaerobic digestion of sludge under laboratory conditions
Discussion
30. Survival of pathogens and parasites during the anaerobic digestion of organic wastes
Methodology
Laboratory digester
Organic wastes
Fermentation experiments
Biogas Analysis
Chemical Analysis
Microbiological determinations
Results and discussion
31. Development and application of biogas technology for rural areas of Egypt
Background and objective
The preliminary fact-finding phase
Outline of the R & D activities
The demonstration phase
Future plans
Conclusions
32. Biogas production from kitchen refuses of army camps of Egypt using a two-phase biogas digester
Materials and methods
Materials fed to the digester
Plant description
Inlet tank
Main digester
Gas-holder
Operation of the system
Experimental
Methods of analysis
Methane content in the biogas
CO2 content
Results and discussion
1. Heating
2. Mixing
33. An integrated renewable energy system project overview
Project objectives
Design considerations
System components
Operation concept
Technical Data
34. Biogas from biomass for a Kenya farm service center
Biogas production
Fertilizer production
Plans
Digester at the University of Illinois
35. Mectat's experience in the transfer of Biogas technology    
Field experience in establishing Biogas digesters
An overview of Bio-gas technology application in rural areas of some countries of the Arab World
Syria
Yemen Arab Republic (YAR)
People's Democratic Republic of Yemen (PDRY)
Tunisia
Lebanon
Conclusion
36. The experience of the development and research of Biogas technology in the rural areas of China
Improvement of Chinese digesters
1. New digester building materials
(I) The semi-plastic digester
(II) The red-mud plastic gas holder digester
III) The iron-made domestic digester
2. Use of solar energy with biogas degesters
(I) The combination of hydraulic digester with solar energy heat-collector
(II) The solar energy feedback heated digester
(III) The solar energy hot-water digester installed with heat-exchanger inside
1. Above ground digesters
2. Insulating devices for the hydraulic digester
(I) Macroscopic economic benefit evaluation24
(II) Analysis by country units
(II) Analysis by production team units
37. The Biogas program in India
Historical background
Recent developments
Future plans
Main considerations, research allocations and future directives
38. Summary of the Nepal Biogas program
Country background
Appropriateness of Biogas program in Nepal
History of Biogas program in Nepal
Organizations involved in Biogas activities
Research and development
Future Biogas programs
39. Biogas technology, development and diffusion the Philippine experience
The first seven years
Research and development activities
Commercialization as a means of diffusion
The economics of Biogas system
Available incentives
Constraints and possibilities
Immediate goals and targets
Summary and conclusion
40. Biogas technology, research, development and diffusion projects in Sri Lanka
Historical aspects
Research and development work
1. Gas yields from various raw materials
2. Development of gas utilizing equipment for rural use
3. Investigation of construction aspects and structural behaviour of fixed dome digester. Development of integrated systems.
Training and extension work
1. Training of persons engaged in agriculture and animal husbandry.
2. Training of technical persons.
Concluding remarks
41. Biogas program of Thailand
The biogas program
Resource investigation and assessment
Need indentfication
Research and development (R & D)
Demonstration and promotion (D & P)
Promotion and popularization (P & P)
Conclusion
42. Problems concerning biogas production at farm level in Italy
Abstract
Foreward
Problems upstream of process
Problems in the digestion plant
Out put utilization problems
43. Anaerobic digestion in Portugal
Existing or under construction plants Research and development

^ Top

Sample Chapters


(Following is an extract of the content from the book)
Hide Down

BIOGAS PRODUCTION FROM SOME ORGANIC WASTES

In view of the energy crisis and environmental pollution, biogas technology has recently attracted worldwide attention.

A list of some of the urgent research tasks on biogas was suggested by Sathianathan. This list includes the search for new materials for biogas production. In the present study, a laboratory investigation was undertaken to assess the feasibility of using some organic wastes that were not before investigated as substrates for biogas production. The wastes examined include geranium flour, akalona, and watermelon residues. In Egypt these materials are presently considered useless by-products of geranium oil extraction, the wheat milling process, and watermelon-seed production respectively. Each of the investigated wastes was digested individually or with cow dung at different mixing rations. The cow dung was also digested individually and served as a reference substrate.

MATERIALS AND METHODS

Organic Wastes

Cow dung fresh, undiluted dairy cow dung, Brown Swiss (Breed), was collected from the animal Production Farm of Fayum Faculty of Agriculture. The animal were fed a ration that was composed of approximately 50 percent rice straw and 50 percent of: 65 percent cotton seed meal, 20 percent rice bran, nine percent bran, three percent molasses, two percent lime stone, and one percent NaCl. No antibiotics or other additives were incorporated in the animal ration.

Geranium Flour

An air-dried sample from the residue remaining from geranium plants, Pelargonium graveolens Ait, after extraction of the essential oil, was obtained from a geranium oil extraction plant located in Fayum Governerate.

Akalona

Akalona is the outer portion (epidermis) of the wheat grains which results from the scouring of the wheat grains during the milling process. A sample of "Akalona" was obtained from the Fayum Mill.

Watermelon Residues Citrullus Vulgaris

This material was prepared in the laboratory from a watermelon fruit. After separating the seeds, residues of the watermelon fruit (i.e., rind, pulp and juice) were homogenized in a blender prior to use.

Starter

The starter for anaerobic digestion was prepared from the effluent of an actively operating laboratory digester fed with cow dung. The effluent was passed through four layers of cheesecloth to remove the undergraded materials. The starter was added to all digesters at the rate of 10 percent by volume.

Digestion Apparatus

Batch-fed laboratory digesters were constructed as described by Gamal-El-Din. The digester setup consists of a 1.25 litre brown bottle, a gas-measuring cylinder equipped with a leveling bulb, gas sampling port, and a sidearm through which liquid could be withdrawn or added.

Analytical Procedures

Gas Volume: The biogas produced was collected and measured by liquid displacement in a calibrated gas cylinder filled with Orsat confining solution: 20 percent sodium sulphate and five percent sulphuric acid in water.

Methane Content of the Biogas: This was determined by bubbling a known volume of biogas through 20 percent (W/V) potassium hydroxide solution. The loss in volume of biogas was taken as equal to the carbon- dioxide. The balance was assumed to be methane.

Determinations of Total Solids: (TS), ash, volatile solids (VS), total volatile acids (TVA), pH, alkalinity, and total nitrogen (TN) were made according to the procedures in "Standard Methods" devised by APHA. Organic carbon (OC) was determined by the rapid titration method of Walkaly and Black.

EXPERIMENTAL

The digesters were fed with cow dung, geranium flour, akalona, watemelon residues, or a mixture of a particular waste and cow dung. The proportions of the cow dung in the mixtures, based on the concentration of the total solids in the feed (five percent TS), were 20 percent, 50 percent, and 80 percent.

The required quantities from each waste or from the waste and the cow dung, to give a total solids concentration of five percent, were mixed with 100 ml of the starter and sufficient amount of tap water to give one litre total volume. Each treatment was replicated three times and a set of digesters was prepared for chemical analysis. The digesters was incubated at 350C. Mixing of the digester contents was done manually at the time of gas volume measurement.

The volumes of the biogas produced were recorded daily and biogas samples were analyzed periodically. All gas volumes were corrected to 00C and one atmospheric pressure (STP). The experiment lasted 30 days. Samples from the digester contents were analyzed for TS, VS at the beginning and at the end of the experiment. Determination of pH, TVA, alkalinity was carried out every 10 days.

RESULTS AND DISCUSSION

Feasibility of biogas production from geranium flour (GF), akalona (AK), watermelon residues (WR), and from mixtures of each waste with cow dung (CD) in different proportions was investigated and compared with biogas production from cow dung, which served as a reference substrate.

Prior to the anaerobic digestion, sample from the investigated wastes were analyzed for TS, ash, OC, TN, and pH. The Vs and the C/N ratio of each waste were calculated. The data obtained are summarized in Table 1.

Table 1 Characteristics of the Investigated wastes

WasteTS%VS%VS/TS%OC% TN%C/NpH in 5% TS Slurry
Cow Dung17.6313.6577.42 44.011.3732.107.10
Geranium Flour92.4174.3280.42 40.611.3530.084.80
Akalona91.8588.3296.20 51.591.0350.096.70
Watermelon Residues6.886.12 88.9549.420.36137.285.50

Biogas Production from Geranium Flour (GF)

Geranium oil is one of the major essential oils for export in Egypt. The geranium plant was first grown in Egypt in 1930. Since then, its area has progressively increased to about 14,000 feddans. The geranium cultivated area at fayum Governerate is about 7,000 feddans.

At present, geranium flour, the residue remaining from geranium plant leaves after extraction of the essential oil is either left where it is produced or may be used as a source of energy by direct burning.

The results obtained in the present study showed that the geranium flour and its mixture with cow dung gave lower biogas volumes than those produced from cow dung. The 100 percent "GF" digesters produced the lowest biogas volumes with low methane content. This result could be explained by the low initial pH value (5.0) of the "GF" digester contents. McCarty reported that methane production proceeds quite well as long as the pH is maintained between 6.6 and 7.6, with an optimum range between 7.0 and 7.2. At pH values below 6.2, acute toxicity occurs.

Table 2      Changes in pH, Alkalinity and Total Volatile Acids (TVA) concentration during the anaerobic digestion of Geranium Flour, Cow dung and different mixtures of the two Wastes at 350C.

Figure 1 Cumulative Biogas volume and biogas production rate (STP) from batch digestion of geranium flour cow-dung and mixtures ofthe two wates at 35°C (geranium flour 100%__80%__50%__20%__cow-dung 100%__ ). *Average CH4 percentage.

The analysis of the effluent after the 30 days digestion period (data not presented) indicated that the approximate percentage VS destruction incase of geranium flour was 3.9 percent as compared to 36.1 percent for the cow dung. This build-up of solids in the "GF" digesters without a significant increase in TVA concentration suggests that "GF" is resistant to attack by the bacterial population.

In addition to the effect of the low pH, the geranium flour may contain an antimicrobial substance(s). Drabkin studied the phytocidal substances of pelargonium and found that the sap of fresh, crushed, leaves and that of autoclaved leaves has an anti-mircrobial activity which was particularly high in the case of the autoclaved leaves.

The results also showed that the biogas production rate dropped to practically zero in the case of the 80 percent GF and the 50 percent GF digesters before the end of the experimental period. According to Kroeker, digester failure appeared to occur approximately at pH 6.5 when the concentration of TVA was 1650 mg/L as acetic acid.

From the results obtained, it may be concluded that under the conditions of the present study, geranium flour is not a convenient substrate for bio-gas production, since it is not easily degradable and should be pretreated to be more suitable for bacterial attack. In addition, adjustment of the pH of the waste slurry is needed. However, it seems doubuful whether the cost of pretreatment of the waste and/or chemical addition can be offset by the increase in gas production.

Biogas Production from Akalona (AK)

Akalona represents about 0.5 percent of weight of the wheat grains. At present, it is considered as useless residue because it is not usable as animal fed, nor is it profitable for further processing.

The results of the anaerobic digestion of akalona showed that "AK" digesters produced lower biogas volumes than those produced from the "CD" digesters. However, such a result was expected because of the relatively high C/N ratio of the former waste (about 50).

Accumulation of TVA was observed in the akalona digester contents (3282 mg/L as acetic acid/30 days). This caused a drop in pH from 6.6 to 4.6. The combined effect of pH depression and TVA concentration increase may include toxic conditions. It seems that the low alkalinity found in the akalona digester (584 mg/L as CaCo3), at the end of the experiment cannot protect the system. McCarty indicates that a bicarbonate alkalinity in the range of 2500 to 5000mg/L as CaCo3 provides a safe buffering capacity for anaerobic treatment of wastes.

The performance of the digesters fed with different mixtures of "AK" and "CD" was highly variable, and this makes it impossible to draw general conclusions. However, at about the 20th day of digestion, the cumulative volumes and the methane content of the biogas produced from both the "20 percent AK" and "CD" digesters were approximately equal. This means that akalona, without any pretreatment, can replace about 20 percent of the cow dung solids for biogas production.

Figure 2 Cumulative Biogas volume and biogas production rate (STP) from batch digestion of akalona, cow-dung and mixtures ofthe two wates at 35°C (akalona 100%__80%__50%__20%__cow-dung 100%__ ). *Average CH4 percentage.

Table 3      Changes in pH, Alkalinity and Total Volatile Acids (TVA) concentration during the anaerobic digestion of Akalona, Cow dung and different mixtures of the two wastes at 350C.

In conclusion, the biogas production from akalona can be improved by nitrogen and/or alkali addition to overcome low pH caused by the rapid formation of the volatile acids. This can be achieved by mixing the akalona with a nitrogen-rich waste such as poultry excreta.

Biogas Production from Watermelon Residue (WR)

In Egypt, more than 3000 feddans of watemelon per year are cultivated for the production of seeds. The watermelons from this area produce about 15,000 tons of juice as a by-product. In addition to the juice, other residues are produced, i.e., rind, pulp, and fibers. Khattak found that charliston watermelon fruits contain about 33.6 percent juice, 43.4 percent rind, and 24 percent seeds, pulp and fibers. They also found the total carbohydrate content of the watemelon juice (reducing and non-reducing sugars) ranged from 6.26 to 7.28 gm/100 ml juice.

Presently, the watermelon residue are considered a useless by-product of the seed-production industry. Because that watermelon juice is rich in sugars, it can represent a serious pollution problem. Some proposals have been made to recover useful products from the watermelon juice. However, none of the systems so far suggested have yielded a satisfactory result.

Regarding biogas production from watermelon residues, the data obtained in the present study showed that the "WR" digesters produced low bio-gas volumes of a relatively low methane content; and generally the bio-gas production and methane content increased by increasing the percentage of cow dung in the mixture. Such a result is not surprising since the C/N ratio (about 137) and the pH value (about 5.5) of the watermelon residues are not favorable for anaerobic digestion.

Table 4      Changes in pH, Alkalinity and Total Volatile Acids (TVA) concentration during the Anaerobic digestion of watermelon residues, Cow dung and different mixtures of the two Wastes at 350C.

The high C/N ratio and the low pH caused as increase in TVA concentration and a decrease in pH. Both affected the activity of the methane-forming becteria. Moreover, the marked drop in the pH value of the "WR" digester contents may inhibit the acid-producing bacteria. It was found that the optimum pH for the separate acidogenesis of soluble carbohydrate containing wastewaters is in the range of 5.7-6.0.

Figure 3 Cumulative Biogas volume and Biogas production rate (STP) from batch digestion of watermelon resifues, cow-dung and mixtures of the two wates at 350C (watermelon reaiduea 100%_80%_50%_20%_cow-dung 100%_).Average CH4 percentage.

In conclusion, the watermelon residues should be pretreated before they can be successfully treated with the anaerobic digestion process. Pretreatment could include pH adjustment to 7.0 and nutrient addition, particularly nitrogen. Reducing the loading rate may also improve the biogas production. Also two-phase anaerobic digestion could be suitable for treating these residues. Because this type of waste would cause serious pollution, additional work is required to identify the suitable pretreatment.


^ Top


blog comments powered by Disqus

Post   Reviews

Please Sign In to post reviews and comments about this product.

About NIIR PROJECT CONSULTANCY SERVICES

Hide Down

NIIR PROJECT CONSULTANCY SERVICES (NPCS) is a reliable name in the industrial world for offering integrated technical consultancy services. Its various services are: Pre-feasibility study, New Project Identification, Project Feasibility and Market Study, Identification of Profitable Industrial Project Opportunities, Preparation of Project Profiles and Pre-Investment and Pre-Feasibility Studies, Market Surveys and Studies, Preparation of Techno-Economic Feasibility Reports, Identification and Selection of Plant and Machinery, Manufacturing Process and or Equipment required, General Guidance, Technical and Commercial Counseling for setting up new industrial projects and industry.

NPCS also publishes varies technology books, directory, databases, detailed project reports, market survey reports on various industries and profit making business. Besides being used by manufacturers, industrialists and entrepreneurs, our publications are also used by Indian and overseas professionals including project engineers, information services bureau, consultants and consultancy firms as one of the input in their research.

^ Top

Products & Services

Others

Contact Us

My Account

Help

Payment Options

  • Credit Cards
  • Debit Cards
  • PayPal
  • Net Banking - (All Major Indian Banks)

We Process

  • Cards

Google Search


Search books



Subjects