The Treatability Study of High Strength Pet Food Wastewater: A Continuous Flow Aerobic System Performance Evaluation

Abstract

This paper presents continuous flow two stage activated sludge treatability studies for the treatment of pet food wastewaters characterized by oil & grease concentration of 50,000-66,000 mg l(-1), total COD & BOD concentrations of 100,000 mg l(-1) and 80,000 mg l(-1), respectively. A pre-treatment system, dissolved air flotation (DAF) achieved 97-99% reduction in oil and grease down to about 400-800 mg l(-1). The pilot experimental results showed that for the DAF pretreated effluent, 97% soluble COD removal efficiency can be achieved by using two stage conventional activated sludge system at a 6-7 days HRT and applied initial soluble COD to biomass ratio of 1.17 mg COD mg VSS. Meanwhile, the system achieved 99.9% soluble BOD removal. Analysis of system kinetics indicated that this particular wastewater is very difficult to biodegrade, with an extremely high half velocity constant "Ks" of 5800 mg l(-1). The research showed the potential applications of activated sludge systems for the treatment of high oil and grease wastewater.

Treatment of High‐Strength Pet Food Wastewater Using Two‐Stage Membrane Bioreactors

“…Generally, a single‐stage conventional activated sludge (CAS) system treating high‐strength wastewater will produce a significant quantity of sludge and therefore is best operated at relatively short sludge ages, which are not conducive to nitrification ( Campos et al, 1999 ), particularly with high variability of influent ammonia. Liu et al (2004) assessed a two‐stages CAS system to treat high‐strength pet food wastewater and achieved 99% BOD 5 removal combined in two stages, but could not nitrify in the second stage as intended, which was attributed to limitations of the clarifiers. In the conventional approach of solid‐liquid separation using clarifiers, maximum biomass concentration possible in the reactor is 3 to 6 g/L, depending on settling characteristics of the sludge ( Metcalf & Eddy, 2002 ).…”

A novel two-stage MBR denitrification process for the treatment of high strength pet food wastewater

“…Inhibition of nitrifiers by the organics [20] remaining in the 1st stage effluent is postulated to reduce the ammonia removal efficiency of such two stages systems. Two-stage conventional aerobic activated sludge system (CAS), experimented by Liu et al [21], removed 99% BOD treating high strength oily pet food industry wastewater, but did not achieve the desired nitrification, which was attributed to limitations of clarifiers. In order to overcome these limitations, application of a membrane in the 1st stage aerobic reactor can create a high rate organics removal step by maintaining high biomass concentration, rendering minimal BOD in the effluent for successful nitrification in the 2nd stage.…”

Treatment of High Strength Pet Food Wastewater Using Two Stage Membrane Bioreactors

“…Generally a single stage conventional activated sludge (CAS) system treating high strength wastewater will produce significant quantity of sludge and therefore is best operated at relatively short sludge ages, which are not conducive to nitrification (Campos et al, 1999), particularly with high variability of influent ammonia. Liu et al (2004) assessed two stages CAS system to treat high strength pet food wastewater and achieved 99% BOD 5 removal combinely in two stages, but could not nitrify in the second stage as intended, which was attributed to limitations of the clarifiers. In the conventional approach of solid liquid separation using clarifiers, maximum biomass concentration possible in the reactor is 3 to 6 g/L depending upon settling characteristics of the sludge (Metcalf & Eddy, 2003).…”