Treatment of waste water from meat industry

Abstract

Slaughter houses and meat processing industry produce large amounts of waste water with high fat, grease and protein content with BOD level of 1500–2000 mg/L. Because of the possible pollution of water sources, the efficient disposal of effluent from meat plants is important. In India, most of the slaughter houses do not have the technology to effectively collect blood, separation of manure or effluent treatment methods. Thus extremely complex effluents are discharged into land or water. Abattoir effluent treatment process mainly includes three steps such as preliminary/primary treatment, secondary treatment and tertiary treatment. Preliminary treatment is based on the physical removal of solids present in the effluent and it works based on three principles like usage of screens, air floatation methods and physico-chemical treatment. Secondary treatment is carried out using biological treatment systems, which involves mixing of culture of microorganisms. These organisms utilize the continuous supply of organic matter present in the effluent to synthesize new cells. Selection of the most suitable secondary system depends on costs, BOD level required, land area available, odour level, etc. Anaerobic process is carried out in totally enclosed systems to prevent the entry of air. It will result in a fast reduction of organic material by a two-stage fermentation process with the production of biogas. The main aerobic treatments include activated sludge process, trickling filters, lagoons, evaporation and irrigation. Combination of anaerobic and aerobic methods is the most suitable effluent treatment for meat industries. Final treatment provides the final removal of contaminants and discharged into the environment without much of risk. Several options are available for discharging effluent in soil. After secondary treatment, two types of material will be available, sludge and treated water. Liquid is treated with chorine or other suitable disinfectant like QAC and discharged into natural bodies and sludge is used for landfill purpose, composting, manure, soil conditioning, etc.