Comparing the effects of three pre-treatment disintegration techniques on aerobic sludge digestion: biodegradability enhancement and microbial community monitoring by PCR–DGGE

Abstract

The objectives of this work were to compare and investigate the effect of three activated sludge disintegration processes before aerobic sludge digestion on 1) aerobic biodegradability enhancement and 2) microbial community evolution using the polymerase chain reaction-denaturant gel gradient electrophoresis (PCR-DGGE) technique. The comparison of three disintegration processes: thermal treatment (95 degrees C, 2h), sonication (100,000 kJ/kgTS) and ozonation (0.108 g O3/gTS) showed that the disintegration processes acted differently according to the composition of the soluble phase and to the DNA damage. Thermal treatment led to significant protein solubilization and to DNA modification. Sonication and ozonation resulted in similar soluble phase compositions and did not lead to any DNA modifications. During activated sludge aerobic digestion, intrinsic biodegradability enhancement was observed for thermal and ozone activated sludge pre-treatments. The analysis of the DGGE patterns at the end of aerobic digestion showed that population diversity was affected by both the aerobic digestion and the pre-treatment. The dissimilarity percentages measured at the end of aerobic digestion in the control sample and in the treated sludge were equal to 22, 25 and 20% for thermal treatment, sonication and ozonation respectively. This study indicated that PCR-DGGE could be a useful tool for the comparison of disintegration processes before and after aerobic digestion.

Physical and biochemical changes in sludge uponTubifex tubifexpredation

“…These costs have stimulated many research projects that aim to minimize the amount of WAS that has to be disposed. Some methods are aimed at increasing the rate and extent of hydrolysis during anaerobic digestion by physical and/or chemical methods or enzymatic pre-treatment of the sludge [4][5][6]. Other methods are aimed at reducing excess sludge production by increasing the sludge age [7][8][9] and thus increasing cell lyses and cryptic growth mechanics [10], which in turn results in a decrease in sludge production.…”

Integrated Biotechnology Management of Biosolids: Sustainable Ways to Produce Value—Added Products

“…Based on the global CO 2 production, sludge degradability improved for thermal and ozonation PT. But, no real improvement in biodegradability was observed for sonication assisted aerobic digestion (Jaziri et al, 2012). Combining microwave and alkali PTs improves the rate of solubilization while reducing the energy consumption and reaction time when compared to microwave or alkali PT alone.…”

“…Three different PTs, ultrasonication, ozonation, and thermal, were used prior to aerobic digestion. Total solid reduction and aerobic biodegradability were monitored to assess the performance of PT (Jaziri et al, 2012). TSS removal improved by 15 and 5% for ultrasonication and thermal assisted aerobic digestion.…”

Unravelling the protein preference of aquatic worms during waste activated sludge degradation

“…Biochemical and physicochemical techniques such as enzyme dosing, ozonation, sonication and thermal treatment aim to improve the solubilisation of WAS, thereby increasing hydrolysis rates [4]. Other methods focus more on minimising the production of WAS.…”