An improved primary wastewater treatment system for a slaughterhouse industry: a full-scale experience (original) (raw)

The effluent streams from the individual slaughtering operations were segregated based upon degree of similarity and treated separately. The wastewater from lairage and paunch sections was dominant in suspended solids (SS: 6,000–25,000 mg/L) and was separated with hydrasieve (500 μ) and externally fed rotary drum filter (EFRDF, 200 μ), respectively. The SS removal efficiency of hydrasieve and EFRDF was 75 and 55%, respectively and remaining solids were removed through a primary clarifier. The fats, oil & grease (FOG: 12,000–35,000 mg/L) containing streams from the hide fleshing, rendering, intestine, and tripe washing were routed through a skimming tank. The SS and FOG removal efficiencies through the skimming tank were 75 and 90%, respectively. FOG remaining after the skimming tank was removed using dissolved air floatation (DAF) that achieved 95% FOG removal. In addition, the efficiency of chemical oxygen demand (COD) removal through the primary treatment system was more than 80%....