New process for physico-chemical pretreatment of dairy effluents with agricultural use of sludge produced

A combined physico-chemical process is suitable for the effective pretreatment of dairy effluents, achieving almost complete removal of fat, and considerable reduction of protein content. The specific cost of COD removal using the process is only half or a third of that using aerobic biological methods. Depending on the chemicals used, further treatment or, in certain cases, agricultural utilization, of the sludge is possible. In addition, the components remaining in the effluent have low molecular weights, are easily degradable, and are very favourable as nutrients in municipal aerobic post-treatment. Investigation of the sludge showed that it did not contain any pathogen organisms and therefore its application on land is recommended. Laboratory and field experiments have shown that, with agricultural use of the sludge, increased plant growth and grain production were achieved.