Initial studies on the temperature-phased anaerobic biofilter process

Abstract

The temperature-phased anaerobic biofilter (TPAB) process is a new high-rate anaerobic treatment system that includes a thermophilic biofilter connected in series to a mesophilic biofilter providing for two-temperature. two-phase treatment.Three TPAB systems with thermophilic:mesophilic reactor size ratios of 1:7, I:3. and I: I were operated at system hydraulic retention times (HRTs) of 24. 36. and 48 hours at temperatures of 56°C in the thermophilic phase and 35°C in the mesophilic phase. The three TPAB systems achieved soluble and total chemical oxygen demand (COD) reductions in excess of 97% and 90%. respectively, for a synthetic milk substrate over a range of system COD loadings from 2 to 16 g COD/L/ d. There was little difference in performance between the three TPAB systems based on COD reduction and methane production, making it feasible to use a smaller thermophilic first phase in the TPAB system.At the 48-hour system HRT, the 6-hour thermophilic phase biofilter reached saturation loading at a COD load of 48 gil/d. After further increases in organic loading, the methane production decreased in the thermophilic first phase and increased in the corresponding mesophilic second phase while levels of n-valeric and butyric acids increased significantly. It is proposed that a microbial population shift occurred in the thermophilic first phase at high organic loadings at low HRTs. Although a decrease in methane production from the thermophilic phase was observed, the performance of the overall two-stage TPAB system did not decline.The TPA B systems were observed to outperform single-stageanaerobic filters operated at equivalent HRTs and organic loadings. Water Environ. Res .. 67, 1095Res .. 67, (1995.

Applications of two-phase anaerobic degradation in industrial wastewater treatment

“…A pilot-scale two-phase digestion plant was operated with 80:20 (weight ratio) RDF-sludge blends to show that this process exhibited a higher methane yield, and produced a higher methane-content digester gas than those obtained by single-stage, high-rate anaerobic digestion. The two-temperature, two-phase anaerobic biofilter systems (Kaiser et al, 1995) were observed to outperform single-stage anaerobic filters operated at equivalent HRTs (24, 36, and 48 hours) and OLR (from 2 to 16 kg COD/m 3 .d) for synthetic milk substrate. studied three anaerobic process configurations -namely, two-phase duel sludge (TPDS), two-stage single sludge (TSSS), and single-stage for effluent COD concentration.…”

Food processing waste

“…DAIRY Ross and Valentine (1994) reported on the performance of an upflow, hybrid sludge bed/fixed film anaerobic system for the pretreatment ofa combined dairy and juice wastewater. A sequential, thermophilic/mesophilic anaerobic batch reactor process was evaluated for treatment ofa synthetic nonfat dry milk wastewater (Kaiser and Dague, 1994;Kaiser et al .. 1994). (1994a) demonstrated the efficiency of the upflow anaerobic filter for treatment of dairy wastewater.…”

Changes in Dewatering Properties Between the Thermophilic and Mesophilic Stages in Tpad Systems

“…The retrofit of two existing digesters with heat provided from a submerged combustion burner led to an increase in gas production and a surplus of thermal energy (Kugel et al 1992). Kaiser et al (1995) conducted studies on a lab-scale temperature-phased anaerobic biofilter (TPAB) system fed synthetic milk substrate (2-16 g COD/L/day). The set-up consisted of a thermophilic HRT of 3, 4.5, and 6 hours with a system SRT of 24, 36 and 48 hours.…”