Technical papers
Distillery effluent treatment and disposal
Distillery Effluent is peculiar in nature characterized by very high organic matter concentration and extremely low pH. Anaerobic Digestion Process has established as most successful primary treatment, due to its advantages like: reduction of organic matter concentration with lower energy input, low sludge development, higher flexibility for variable loading and, above all, generation of Non - conventional energy in the form of biogas, which can substitute a substantial portion of fuel requirement of the parent industry.Zero pollution by distillery effluent - technical approach
The spent wash coming out of distillery is passed through heat exchanger to reduce the temperature from incoming 90o-100o C to 30o-40o C. This is found necessary, as the major culture grouping is in mesophillic range. The initially neutralized effluent is then taken to the 1st phase process of Acid Formation.The basic operation is divided into two phases as it is necessarily a two phase operation and which gives greater stability to 2nd phase operation of 'methane phase'. The effluent after acid formation enters the 2nd phase reactor, wherein it is conditioned with return sludge/supernatant. Multiple entry inlet and weir outlet combined with higher flow through jet mixers and sparger mechanism with high velocity gives the Up flow sludge blanket reactor with 'complete mix' facility. The effluent after methane phase reactor is subjected to flash degasification to release entrapped gases. This is thereafter subjected to settling operation to avoid carryover of biomass/solids which is recycled back to the digester for maintenance of biomass. The supernatant is also partially recycled to maintain inlet conditions as per design. The biogas is collected into a storage tank with pressure maintenance facility and is used in the combustion device or flared.
The basic advantage of the process is this overcomes all the practical problems of various sub techniques, which is required to suit Indian Working conditions.
Composting is the decomposition of heterogeneous organic wastes by a mixed microbial population in a moist, warm, aerobic environment. By gathering the inert base material of Filter Cake from Sugar Factory into heaps and Spraying with the Spentwash, along with the culture dosage, by conserving some of the heat of fermentation, the temperature rises and rates of degradation result which are far higher than those achieved under ambient conditions. The mature end product is 'humus' consisting largely of the humic acids. The aim of composting is to convert a major proportion of organic wastes into a marketable product. A judicial combination of treatment disposal techniques in the form of Anaerobic Digester and Composting with Filter Cake from sugar factory is successfully working at many factories. This is so because it is unwise to waste the energy source available and which can satisfy almost 90%of distillery (steam) requirement. In addition, there is no liquid waste remaining for disposal. It is however observed that in most of the cases, the material balance requirement of Composting Process is not fulfilled; forcing the distillery managements to discharge untreated / partially treated effluent in the environment / river for dilution. This specifies the need of adopting a 'Composite Approach' wherein after Anaerobic Digestion, with the help of Multi Effect Evaporator, the anaerobically digested Spentwash is reduced to desired volume suitable for the mass balance of the composting process and Filter Cake availability. This will also result in utilizable water of neutral pH and low organic matter concentration to be reused after treatment. This technique is really useful in achieving the full proof technology of zero pollution by adopting the approach of, Biodigestion + MEE + Aerobic Composting
By adopting the above technology, it is possible to achieve not only zero pollution but also will utilize fully the nutrient values and organic matter of Spentwash for the resource generation.