Anaerobic digestion is gaining enormous attention due to the ability to covert organic wastes into biogas, an alternative sustainable energy. Methanogenic community plays a significant role in biogas production and also for proficient functioning of the anaerobic digester. Therefore, this study was carried out to investigate the methanogen diversity of a food waste anaerobic digester. After endogenous respiration, the digester samples were supplemented with isotopes of acetate to enrich methanogen population, and were analyzed using DNA-SIP (Stable-Isotope Probing). Following separation and fractionation of heavy (13C) and light (12C) DNA, PCR amplification was carried out using archaeal 16S rRNA gene followed by DGGE analysis. Sequencing of the prominent DGGE bands revealed the dominance of Methanocorpusculum labreanum species belonging to hydrogenotrophic Methanomicrobiales, which can produce methane in the presence of H2/CO2 and requires acetate for its growth. This is the first instance where Methanocorpusculum labreanum is being reported as a dominant species in an anaerobic digester operative on food waste.

To control and regulate the biogas process there are online process parameters and offline process parameters, which basically don’t differ between pilot biogas plants and industrial biogas plants. Generally, temperature, pH-value, volume flow rate and sometimes redox potential are measured online. An online-measurement of the dissolved volatile fatty acids and an online-detection of dissolved hydrogen both directly in the liquid phase as well as near-infrared spectroscopy are under development. FOS/TAC-analysis is the most common offline-analysis of the biogas process and normally it is carried out by the plant operator directly at the biogas plant. For example dry matter, organic dry matter, nitrogen and fatty acids are other analyses, which are carried out but by a laboratory. Microbiological analyses of biogas plants are very expensive and time-consuming and are therefore in Germany very rare. Microbiological analyses are mainly for research purposes. For example the Fluorescence in situ Hybridiation (FISH) is used for characterization of the populations. Electric-optical measurement should be established as a new method to investigate the vitality of the methane producing microorganisms. In a cooperation project, which is promoted by the German ministry for technology, between IASP and Chair of Bioprocess Engineering at TU Berlin, this method is proper investigated using a device from the firm EloSystems. The microorganisms are brought in an electrical field of different frequencies. In this field the microorganisms direct themselves differently according to their physiological state. At the end of this project an early detection of process disturbance will be possible with the help of this method. In this presentation the result of the first tests are presented.

Biogas is one of the most promising sources of renewable energy in today’s world. Liquid and the solid digestates are the byproducts of anaerobic digestion of various kinds of wastes to produce biogas. Disposal of liquid digestate is one of the major issues faced by the existing biogas plant facilities worldwide. In this study, liquid digestate from anaerobic digestion of food waste is examined for its potential as an organic fertilizer for food crops. Coconut peat is used as a matrix to hold the digestate and also to grow plants in a soil-less culture. Three plants from the family- Solanaceae were chosen viz. tomato (Solanum lycopersicum), green chilli (Capsicum annum) and eggplant or brinjal (Solanum melogena). The plants were grown in trays as control (coconut peat and water) and slurry (coconut peat and digestate). Digestate sets showed an increase in growth parameters as compared to control by a factor of 60.8% in tomato, 48.6% in chilli and 97% in brinjal for plant height, 86% in tomato, 82.4% in chilli and 63.8% in brinjal for leaf length, and 66.3% in tomato, 87.3% in chilli for number of leaves. The final yield for chilli plants was 2.5 fruits/plant in 70 days while for brinjal it was 2 fruits/plant after 74 days of growth.

The demand for energy and the fertilizers are ever increasing. Organic farming has many advantages looking to the environment pollution, unproductive soil, less yields etc. By installation of a biogas plant serves both the purposes of meeting the fuel as well as obtaining manures. The organic manures need to be added in bulk to meet the nutrient demands of the crop as it is not in concentrated form like chemical fertilizers. Hence, biogas spent slurry is the best alternate for hastening the compost preparation of abundantly available crop residues as well as obtaining enriched compost as conventional method takes long time. Moreover, slurry is composed of major nutrients besides enzymes and a rich microflora. Based on the preliminary results, the present study was conducted at farmer’s field to know whether slurry could be used for degradation of agro residues. One ton of crop residues that included banana waste, sunflower and maize waste, leaf litter of horticultural crops were inoculated individually with 60 L of spent slurry along with consortia of degrading fungi and P-solubilising bacteria. After a retention period of 60 days, nutrients were analysed. The cultures along with slurry indicated 1.5 - 1.96 % N with reduction in C:N ratio between 1.6 - 1.82. The micronutrients also increased. Thus, it was concluded that efficient use of spent slurry can be made besides utilising the crop residues and the product for organic cultivation.

Indian state Punjab produces 160 lakh tones of paddy every year. More than this quantity of paddy, straw is also produced which is not properly utilized. Paddy is burnt in the farmer’s fields itself, which produces lot of smoke and atmospheric pollution. Farmers have their own difficulty for burning this valuable straw as they have to vacate the fields for the next crop. Biogas production is one alternative for the individual farmer, for individual village or on the regional basis. In our opinion, it is possible to digest paddy straw anaerobically for biogas production and the digested humus would be utilized as crop manure. Anaerobic digestion of crop waste cannot be done by conventional anaerobic process for biogas production because of the floating characteristics of paddy straw in water. New process of anaerobic digestion has to be followed with small quantity of water to avoid floating of paddy straw. This process is commonly known as dry fermentation. This technique is well known in United States, Taiwan, German and Sri Lanka. In these countries, steel containers are being used as digester for anaerobic digestion. Digester of steel is ideal but the cost involved is very huge. Attempts have been made at PAU to construct masonry structure as digester but lot of difficulties were being faced to make it gas tight. The PAU has found suitable method to make the digester strong and gas tight. The life of structure will be more than 15 years. The advantage of the masonry structure is that the whole structure will be underground on which cold would have little effect in winter. This process of Dry Fermentation is a batch process, once the digester is loaded and activated, would produce sufficient gas for a period of 3 - 4 months. Therefore, 2 sets of digester are required to meet the whole year demand.

Indian state Punjab produces 160 lakh tones of paddy every year. More than this quantity of paddy, straw is also produced which is not properly utilized. Paddy is burnt in the farmer’s fields itself, which produces lot of smoke and atmospheric pollution. Farmers have their own difficulty for burning this valuable straw as they have to vacate the fields for the next crop. Biogas production is one alternative for the individual farmer, for individual village or on the regional basis. In our opinion, it is possible to digest paddy straw anaerobically for biogas production and the digested humus would be utilized as crop manure. Anaerobic digestion of crop waste cannot be done by conventional anaerobic process for biogas production because of the floating characteristics of paddy straw in water. New process of anaerobic digestion has to be followed with small quantity of water to avoid floating of paddy straw. This process is commonly known as dry fermentation. This technique is well known in United States, Taiwan, German and Sri Lanka. In these countries, steel containers are being used as digester for anaerobic digestion. Digester of steel is ideal but the cost involved is very huge. Attempts have been made at PAU to construct masonry structure as digester but lot of difficulties were being faced to make it gas tight. The PAU has found suitable method to make the digester strong and gas tight. The life of structure will be more than 15 years. The advantage of the masonry structure is that the whole structure will be underground on which cold would have little effect in winter. This process of Dry Fermentation is a batch process, once the digester is loaded and activated, would produce sufficient gas for a period of 3 - 4 months. Therefore, 2 sets of digester are required to meet the whole year demand.

Stored grains such as rice and wheat (and other grains/pulses) are prone to pest infestation mainly by Sitophilus oryzae, Tribolium castaneum and Rhyzopertha dominica in India and more than 30 % of harvested grain is lost to stored grain pests. Protection of the grains by creating an oxygen deficit atmosphere by using carbon-dioxide or biogas is an alternative. In this study, biogas was used as a ‘fumigant’ against S .oryzae, T. castaneum and R. dominica reared on rice (Oryza sativa) and wheat (Triticum aestivum; Semolina and whole wheat flour) grain types, respectively. The optimum biogas flow rate required to remove the oxygen from an empty container and partially grain filled container was found to be 40 ml per minute sustained up to a time leading to an equivalent of three times the volume of the grain container. Using these fumigation conditions 100 % adult mortality was observed in T. castaneum and R. dominica within 24 hours and S. oryzae within 48 hours. Farmers in rural India have been using biogas plants to meet their kitchen energy needs. Some surplus gas could be used for fumigation of stored agro-products making this process inexpensive, environment friendly as well as acceptable to a growing ‘organic food market’.

The increasing levels of generation of nutrient-rich waste water pose serious challenge. Conventional biological and chemical methods of waste water treatment have failed in meeting sustainability challenges. Naturally occurring mixed algal species reared in mixotrophic growth modes have been deployed to recover nutrients (N and P) from domestic wastewater after anaerobic digestion. In this paper, we present the results pertaining to growth and mixotrophy. Pilot-scale operation shows that the cultivation methods adopted and the use of naturally selected species lead to a tendency among these species to clump at certain stages of growth that in turn float or settle rapidly making algal harvest and thereby the nutrient recovery processes energy efficient. The highest settling rate was found to be 6.37 ± 1.6 g/m2/d. Mixotrophy was seen to contribute 15 – 24 % across the various algal consortia in wastewater (polyculture).

This paper aims to evolve innovative system for fast track implementation of decentralized power generation by biogas digester across the country commensurate with estimated potential of this energy resource. The methodology is based on the principle that necessity of a process or facility for human liveli hood generates demand of a new system if that is competitive enough to impress society by its value to meet the standard of usability economically and technically in all respect. Firstly, the study described a network of communication to propagate knowledge about the benefit, cost and operation of biogas digester to serve multiple purposes among policy makers and other stakeholders all over the country through distance mode programme and training of the human resources by simulating the process for training programme. Secondly, analysis by cause and effect method focused on major issues related to implementation of power generation by biogas that identified factors corresponding to the problems. Next the study attempt to focus on supply chain management for controlling those factors supported by administration with financial, technical facilities ensuring trouble free dynamic process from procurement of substrate through input to digester till delivery of electricity to the consumers. The study identified driving variables between resource centre and delivery stage of the supply chain that has influence on methane production related to power generation. The mathematical analysis reveal that optimum yield of biogas is independent of daily feed stock and improving methane fraction of biogas is possible by monitoring temperature and pH value within limited span of Hydraulic Retention period (HRT).The study observed by mathematical analysis that cost of power generation from biogas digester is dependent on the cost of substrate for biogas generation and the other fixed cost of the process. Bio gas digester cum power generation policy has been analyzed for rural and urban area focusing on the constraint at different stages.

The samples for food waste (FW) and septage were collected from six localities of Nashik city. Physical and chemical characterizations of the wastes were carried out. A Biomethanation potential (BMP) assay was developed to determine the ultimate biodegradability and associated methane yield during the anaerobic methanogenic fermentation of organic substrates. BMP assays of individual substrate, FW and septage were carried out by taking into account the volatile solids/total solids (VS/TS) ratio of each while keeping the inoculum’s VS constant. BMP of FW and septage mixture was carried out in different ratios (1:1, 1.5:1, 2:1, 1:1.5 and 1:2) to find the optimum mixing ratio for maximum biogas production. The average methane yield for different locality FW was found to be 503±17.6 ml/g VS and for septage it was 56 ±10.8 ml/g VS. Based on the above results, the total biogas yield and total methane yield for 10 tons of FW would be 2178 m3/d and 1306 m3/d respectively. The total biogas yield and total methane yield for 20 m3 of septage would be 65m3/d and 39m3/d respectively. From our co-digestion studies we also conclude that the mixture of FW to septage at 1:2 ratio gives 2896 m3 /day of biogas. The role of septage is to provide essential trace elements that are required for methanogens.

Biogas slurry provides a complete and high growth rate producing algal cultivation medium thus offsetting the high cultivation costs of raising algal cultures in synthetic growth media. Robust mixed algal consortia can also be cultivated in non-traditional media such as wastewater or biogas slurry along with flooded agricultural crops such as paddy (Algiculture). This greatly enhances the Nsustainability of the algae cultivation. However, since the biogas slurry contains its own set of predators of algal biomass (grazers), it is now important to study the productivities attainable by using slurry in the conventional open ponds and Algiculture setup and understand its impact on grazer population dynamics. In this study we have used diluted biogas slurry (1:10) as growth media and compared algal growth and grazing /predation characteristics for algae cultivated under four treatments namely, Bold’s basal media (M), biogas slurry (S), Algiculture (ALGI), Algiculture with biogas slurry as growth stimulant (ALGI-S). The algal biomass cultivated in slurry based systems gave rise to a productivity of 6.8 g/m2/d as harvestable biomass with simultaneous reduction in the algal mass sacrificed to grazers. We thus attempt to show that biogas slurry may be used as a potential growth media especially in Algiculture system which tends to be vulnerable to grazer attack and loss of algal population.

The increasing levels of generation of wastewaters which are nutrient rich pose serious issues where conventional biological and chemical methods of treatment have failed in meeting sustainability challenges. In this study naturally occurring mixed algal species reared in mixotrophic growth modes have been deployed to remove recalcitrant organics and recover high nutrient concentrations (N and P) from anaerobic digestor wastewater at short residence times of 6-7 days. Results from pilot scale operation show that the cultivation methods adopted and the use of naturally selected species lead to a tendency among these species to clump at certain stages of growth that in turn float or settle rapidly making algal harvest and thereby the nutrient recovery processes energy efficient. Algal biomass productivity in the liquid from anaerobic digestor of the consortia varied with season with a maximum of 6.3 g/m2/d.

Anaerobic fermentation inside the digestor is the continuous process which results in the formation of useful biogas fuel. All feedstocks are not easily decomposable thereby necessitating the design of an “optional in-line pre-digestor assembly”. Initially a 2 m3 modified fixed dome ‘Deenbandhu’ type biogas plant was commissioned with cattle dung, bypassing the pre-digestor assembly. In a phased manner, cattle dung was substituted with poultry litter as feedstock. Gradually increasing the substitution @ of 10% per fortnight, complete substitution of cattle dung could be attained in 18 week time. Poultry droppings assorted with paddy husk from deep litter system of poultry housings were used as feedstock. As paddy husk were indecomposable inside the digestor, an in-line pre-digestor assembly was used to remove the unwanted paddy husk by water dissolution technique. Enzymatic hydrolysis initiated in the pre-digestion tank in the 24 hours residence time improved the digestibility of the feedstock for generating biogas. The process of cattle dung substitution with poultry litter was complete in 18 weeks duration. Daily gas production was recorded with the help of wet type gas flow meter. The gas produced was continuously used for domestic cooking. The total solid (TS) content of the poultry litter based feedstock slurry was maintained at around the same TS (9 - 10%) as that of cattle dung (dung to water at 1:1 ratio) slurry. With 100% use of poultry droppings at 10.3 % TS, average gas production level was 208.5 lit per kg of TS.

Production of activated carbon fibers from fiber waste of pineapple leaf fiber production with phosphoric acid modification by non pre-carbonization activation and pre-carbonization activation processing were studied. The influences of step procedures, carbonization temperature (500 - 700 °C) and activation temperature (500 - 700 °C) on the resulting activated carbon fibers properties were evaluated. The non pre-carbonization activation is activation of fiber waste with H2PO4 of 1:1 ratio at 500-700 °C. For the pre-carbonization activation, it consisted of the carbonization of fiber waste at 500 °C followed by an activation step with H2PO4 of 1:1 ratio at 500 °C - 700 °C. The carbonized and activated products were characterized by SEM- EDS, FTIR, XRD and BET. It was found that percent yields of carbonization and activation products are decreased with increasing carbonization and activation temperature from 500 oC to 700 oC. Percent yield of the non pre-carbonization activated carbon and pre-carbonization activated carbon, which have high content of phosphorus 17.56 - 22.60 wt.%, are much higher than carbon from fiber waste (1.52 - 1.66 wt.%). The both activated carbons are oxygen- and phosphorus-containing groups on the sureface. After carbonization, the all samples are in form groove and streak ridge in parallel follow longitudinal of fibers with uneven and rough, and more broken and contracted after activation. The P, Si, K and Ca elements existed in activated carbon fiber. The best temperature in activation of fiber waste by both activation processes were 600 oC.