Get EFFLUENT GENERATION BY THE DAIRY INDUSTRY: PREVENTIVE ... - Scielo

Dairy wastewater contains large amount chemical oxygen demand (COD), biological oxygen demand (BOD) and nutrients. The COD ranges from 80 mg/L to 95,000 mg/L and BOD ranges from 40 mg/L to 48,000 mg/L, which is a large load of suspended solids (Kushwaha et al., 2011, Vijayaraghavan et al., 2021).

Dairy processing effluents mostly include milk or milk products lost in the technological cycles (spilled milk, spoiled milk, skimmed milk and curd pieces); starter cultures used in manufacturing; by-products of processing operations (whey, milk and whey permeates); contaminants from the washing of milk trucks, tanks, ...

On dairy farms, the liquid waste stream from milking sheds and associated yards is generally referred to as effluent. It consists of the manure and urine excreted in the milking shed and yards, mixed with the wash-down water used to remove the waste from these areas and concrete yard runoff following rainfall.

Effluent is sewage that has been treated in a septic tank or sewage treatment plant. It is also referred to as “trade effluent” or “wastewater.” Effluent is waste other than waste from kitchens or toilets, surface water or domestic sewage. It can be produced and discharged by any industrial or commercial premises.

Generally dairy wastes contain large quantities of milk constituents such as casein, lactose, fat, inorganic salts besides detergents and sanitizers which contribute largely towards high BOD and COD (Marwaha et.al., 2001).

Dairy effluents decompose rapidly and deplete the dissolved oxygen level of the receiving streams immediately resulting in anaerobic conditions and release of strong foul odour due to nuisance conditions. The casein precipitation from dairy waste decomposes further into a highly odorous black sludge.

Operation of dairy industry with effluent treatment: The dairy effluent treatment plant follows a set of steps: The pH is first adjusted to 8.5 using pH controllers such as caustic or acid. Any emulsions are then broken down and solids precipitate with the help of a de-emulsifier.