RESERVES - Resource and energy reliability by co-digestion of veg-market and slaughterhouse waste
The project goal is to demonstrate the feasibility of a sustainable resource and energy reliability by co-digestion of veg-market and slaughterhouse waste in India and its potential for global realization. In a pilot project conducted in Chennai, Tamil Nadu, India on a land provided by an integrated Indian stakeholder the German and Indian partners would like to apply their common developed innovative approach wherein the following sub-goals are planned:
- Demonstration of the feasibility of recovery of bioenergy from slaughterhouse waste, fruit- and vegetable market waste and other organic wastes in urban areas in a sustainable way
- Integration of advanced anaerobic processes in the economic, social and natural environment in context to India
- Establishment of a sustainable supply chain for the generation of energy through anaerobic treatment of slaughterhouse waste, fruit- and veg-market waste and other organic wastes generated in Chennai City as substrates.
- Avoiding emission of Methane into environment by reducing the disposal of organic wastes in open dumps and also reducing the odour nuisance and other land and water pollution.
- Contribution to local energy supply through generation of bioenergy and also generation of bio-fertilisers/soil conditioner with rich nutrient contents (N, P, K) thus making this energy recovery as sustainable with generation of additional income.
- Establishment of employment opportunities, both at the biogas plant as well as along the supply and product chain
- Supporting German companies in accessing the Indian market
- Economic assessment and construction of a prototype system
- Training of qualified staffs for operation and concepts for vocational training
With 15% of the world’s population and an economic growth rate that increases the aspiration of its people to better quality of life, India has a voracious appetite for energy. But the country lacks sufficient domestic energy resources, particularly of petroleum and natural gas, and must import much of its growing requirements. Currently, about 35% of India’s commercial energy needs are imported. The Government of India’s Planning Commission predicts dramatic demand increases for coal and oil over the next 20 years. This increasing energy demand in India brings a several problems to a still agricultural shaped country. An accessible alternative to energy imports and nuclear power is the abounding available biomass from biodegradable wastes to produce biogas through anaerobic digestion (AD). Mass flows like slaughterhouse and fruit- and veg-market waste are not used at all. Biogas from this waste material could be an important and flexible energy source for local consumer with high supply guarantee.
In most towns/cities of developing countries including India, slaughter house wastes are disposed along with other municipal solid wastes (MSW) in open dumping leading to contamination of air, water and land. Similar situation prevails in Chennai City too for slaughter houses wastes management. There is also an urgent need for hygienisation of slaughter wastes with respect to health, environment and society. However, with respect to resources and energy reliability, these wastes are highly valuable and regular/reliable sources of bio-energy. Treatment of slaughter waste alone for bio-energy generation in anaerobic processes is not effective in terms of optimum utilisation and performance of treatment system due to considerable variation in number of animals slaughtered and hence generation of slaughter house wastes depending on the culture and meat eating habits of people. In addition, the animal wastes contain more about of proteineous matter with high amount of nitrogen content and hence these wastes contain less Carbon to Nitrogen (C/N) ratio.
On the other hand considerable amounts an organic waste with high C/N ratio are available in the Chennai city like fruit and vegetable market waste, food wastes, agro-residues, industrial organic waste etc. Both kinds of waste are till now damped in open landfills. The actual situation causes serious, increasing environmental and human health damages beside the potential energy from dumped biomass is lost.
Co-digestion of different waste streams with high and low C/N ratio could enhance the bio-gas production in anaerobic treatment processes; improve the maximum utilisation and its performance of the biomethanisation system and overall sustainability of waste treatment process. Involvement of different substrate sources allows the compensation of fluctuations in amounts on single substrate and support continues plant operation. Figure 1 shows the value creation chain from waste products to voluble products. On side this development allows an increase of sustainability and forms a new procession of economic value. At least the process should be rentable and ensure the local energy supply in form of electrical power and heat or biomethane.
In aspect of co-fermentation of organic waste, the involved German and Indian industries/institutes have complemented experiences on sustainable anaerobic technologies for recovery of renewable energy in the form of biogas and thermal energy. In addition to biogas production, processes and technologies for upgrading and commercial utilisation of biogas are available. Moreover digestate from the anaerobic bioreactor can be used as bio fertiliser thereby ensuring complete utilisation and recycling of nutrients and replacing chemical fertilizers or be upgraded to pellets and used as fuel. Fig. 1 shows the entire value added chain for anaerobic digestion of slaughter-, market- and other org. wastes
Figure 1: Value added chain for anaerobic digestion of slaughterhouse, market and other organic wastes
In the city of Chennai –as an example for other cities in India – fruit- and vegetables markets are operated with insufficient waste management. The same prevails at slaughterhouses. Regarding resource and energy reliability these wastes are valuable and periodic resources. The treatment of these waste streams separately is inefficient. Beside the hygienisation the co-digestion has advantages which should be investigated in detail. For this German technology should be adapted and performed to produce biogas and digestate which reaches prescriptive limits, required standards and good marketable qualities.
Initially it is planned to conduct a joint study with various combination for co-digestion of wastes from slaughterhouses and fruit- and veg-markets and when indicated supplemented by other organic wastes from hotels, food industry, etc. by bench scale tests at CLRI accompanied by ISAH. Suitable combinations and main technologies will be investigated and adapted through pilot-plants for biogas production and bio-extrusion, which increase the bioavailability due to cell disruption by means of bio extrusion- patented technology).
Increased substrate temperature after bioextrusion (value depends on water content of the substrate) effect on the one hand an hygienisation of the substrate on the other hand the energy demand for optional fermenter heating is decreased. The average energy demand for bioextrusion is about 5 kWh/t original substance (corn silage), which is less than 10% of the electrical power produced from biogas. Bioextrusion has through extensive homogenised substrate a positive effect for further processes like hydrolysis, for example the loading rate can be increased.
Furthermore the scheme contains a possibility to process the digestate to fuel or fertilizer. Therefore the digestate residuals, which are produced in large amounts by high loading rates, can be dewatered trough LEHMANN-Solidseparator and used directly as fertilizer or pelletized to renewable fuel.
According to previous realized research, an additional amount of electrical power of 100kWel/t original substance (TS 30%) can be generated through bioextrusion of the digestate. This shows that the bioextrusion significant increases the biodegradability of the substrate.
Within this project, implementer will be identified and transfer of knowledge takes place during the pilot scale study. Sustainability assessment of the process and the marketable product qualities using Life Cycle Assessment (LCA) and carbon footprints investigations will be carried out alongside the value added chain. Sustainable ways for biogas and digestate utilization will be investigated. Herewith material and energy flows will be optimized as well as biogas upgrading and usage efficiency. To ensure the acceptance of this project among various stakeholders, and to confirm the exemplarity of this project capacity building by demonstration workshops/ training programme will be organised.
 2011 India Energy Handbook, PSI Media Inc. Las Vegas, Nev, USA