Effect of thermochemical sludge pretreatment on sludge reduction and on performances of anoxic‐aerobic membrane bioreactor treating low strength domestic wastewater

Abstract

BACKGROUND: Reduction of excess sludge production has become an urgent issue. An investigation into the influence of thermochemical sludge pretreatment on sludge reduction in a bench-scale anoxic-aerobic membrane bioreactor was performed. Two systems were operated. In one system, part of the mixed liquid (1.5% of the influent flow rate) was pretreated thermochemically (at 80• C, pH 11 and 3 h) and returned to the bioreactor. This study examined and evaluated the effect of thermochemical sludge pretreatment on the reduction of excess sludge and on the performance of the system.

Effect of alkaline and ozone pretreatment on sludge reduction potential of a membrane bioreactor treating high-strength domestic wastewater

“…From these observations, it was clearly evident that the alkali-ozone sludge pretreatment in the EMBR accounted for 37% of the reduction in DSP day . The observed excess sludge reduction was comparable with the values of 33 [27] and 42% [4] reported for MBRs, integrated with pretreatment techniques. By considering the economics, proposed method of sludge reduction was feasible than other conventional anaerobic digestion, where it demands high capital cost.…”

“…The Y obs value for both the MBRs was found to be 0.38 kg MLSS/kg COD. The presently observed Y obs value was considerably higher than the values reported for sludge reduction in MBR-treated domestic wastewater [21,27]. However, the wastewater used by researchers [21,27] falls under the category of "low-strength."…”

“…The presently observed Y obs value was considerably higher than the values reported for sludge reduction in MBR-treated domestic wastewater [21,27]. However, the wastewater used by researchers [21,27] falls under the category of "low-strength." It was well known that high-strength wastewater produces more biomass than low-strength wastewater, and this may be the reason for high biomass production observed in the present study.…”

“…Understandably; an increase in pretreatment Q of over 1.5% increases the percentage of sludge reduction. However, it was reported that an increase in the pretreatment of Q of over 1.5% was not an economically viable option [27]. Consequently, it was decided that the pretreatment of Q would be maintained at 1.5%.…”

Various Sludge Pretreatments: Their Impact on Biogas Generation

“…Thermal pretreatment is appropriate for the enhancement of stabilization, improvement of sludge dewatering and reduction of the pathogens (Uan et al 2009(Uan et al , 2012Uma et al 2012a). As the stress and heat of thermal process increases, the organics subjected to treatment transformed to short chain fragments that are well appropriate for biodegradation by microbes ).…”