In an agriculture country like India, less profit in the farming sector, depletion of natural resources and energy crisis are becoming the major challenges for sustainable agriculture. Approximately 500 million tons/year of agriculture waste is produced in India out of which 91 Mt is burnt every year(Hiloidhari et al., 2014). Among the various crop grown, crop residues released from rice, wheat and sugarcane is burnt in larger extent. The crop residues burning instantly release air pollutants such as particulate matters, oxides of carbon, oxides of sulphur, oxides of nitrogen, volatile organic compounds, non- methane hydrocarbons into the ambient environment. It also reduces the fertility of soil by lowering the soil organic carbon, nitrogen and other essential nutrients. In view of the harmful impacts burning of crop residues, stakeholders have adopted alternative ways for its sustainable management such as nutrient recovery, animal fodder, bioenergy generation etc.
Dairy industry is another major agricultural operation with a value of Rs 7, 01,530 Crore (in 2017-2018), which is higher than the value of output of rice and wheat. With the largest bovine population, India ranks first at global level in the milk production since 1998. Despite of the significant contribution in the Nation’s economy, dairy industry is regarded as one of the most polluting food industries(Hung et al., 2005). Dairy wastewater comprises large extent of lactose, other organic compounds, inorganic nutrients which results in high biochemical oxygen demand (BOD) and chemical oxygen demand (COD). Various treatment methods (physical, chemical and biological) have been suggested to remove higher concentrated material like oil, greases, and lactose from wastewater before its final discharge. Biological treatment methods have been observed as most economical and efficient way for dairy industry waste water (DIWW) treatment. Biological processes such as activated sludge process, rotating biological disc and anaerobic digestion are the most common methods for DIWW treatment. Among these processes, anaerobic digestion has been observed as a more efficient way of treatment than the others due to its higher treatment efficiency and energy recovery.
Also, to achieve the sustainability in agriculture sector, an integrated approach is required for the management of different agriculture waste materials. Researcher have evaluated that the overall bioenergy potential of India is about 25,700 MW that involves municipal solid waste, crop residues, agricultural waste, wastewater etc. . In the process of production of biogas from agricultural waste, researchers have analysed various pretreatment methods such as physical by changing size and other conditions, chemical using acidic and alkaline medium and biological using enzymes, fungi or bacteria. Jaffar et al.  studied the efficiency of KOH pretreated wheat straw for biogas production and achieved 45% improvement in the cumulative biogas production than the raw wheat straw. Liu et al.  reported that 20% KOH (for 1 hour) pretreated wheat straw loading at ambient temperature resulted in the maximum methane yield and therefore recommended for the wheat straw pre-treatment loading. On the other hand significant methane yield has been also achieved from anaerobic digestion of DIWW by various researchers [6-7].Co-digestion of DIWW with various organic substrates (slaughter house sludge, food leftover waste, municipal sludge, and industrial waste sludge) has been found more effective than the anaerobic digestion of DIWW as a single substrate [8-9]. The efficiency of co-digestion is directly related to nutrient content, pH buffering capacity, C/N ratio, composition of seed inoculums, substrate ratio and reactor conditions .
Co-digestion of DIWW with wheat straw for biogas production is a novel approach for integrated agricultural waste management. Thus, the present work is an attempt to evaluate the potential of DIWW and wheat straw co-digestion for biogas production. The study also involves investigation on the KOH based pre-treatment of wheat straw and its influence over the yield of biogas production.