Biochar is a massively produced by-product of biomass pyrolysis to obtain renewable energy and has not been fully used. Incomplete separation of sludge and effluent and insufficient denitrification of sewage are two o...Biochar is a massively produced by-product of biomass pyrolysis to obtain renewable energy and has not been fully used. Incomplete separation of sludge and effluent and insufficient denitrification of sewage are two of main factors that influence the efficiency of activated sludge process. In this work, we proposed a new utilization of biochar and investigated the effect of biochar addition on the performance of settleability and denitrification of activated sludge. Results show that the addition of biochar can improve the settleability of activated sludge by changing the physicochemical characteristics of sludge （e.g., flocculating ability, zeta-potential, hydrophobicity, and extracellular polymeric substances constituents）. Moreover, the dissolved organic carbon released from biochar obtained at lower pyrolysis temperature can improve the nitrate removal efficiency to a certain extent.展开更多
Municipal wastewater treatment plants typically exhibit two classic problems： high ammonium concen- tration in water after conventional biological treatment and, in some cases, poor activated sludge sediment ability....Municipal wastewater treatment plants typically exhibit two classic problems： high ammonium concen- tration in water after conventional biological treatment and, in some cases, poor activated sludge sediment ability. Potential solutions to these problems were investigated by adding a synthetic zeolite obtained from coal fly ash to different steps of activated sludge treatment. The experimental results for ammonium removal fit well with the theoretical adsorption isotherms of the Freundlich model with a maximum adsorption capacity of 13.72 mg.g-＇. Utiliza- tion of this kind of zeolite to improve activated sludge sediment ability is studied for the first time in this work. It is found that the addition of the zeolite （1 g. L-1） to an activated sludge with settling problems significantly enhances its sediment ability and comoact ability. This is confirmed by the sludge volume index （SVI）, which was reduced from 163 ml.g-1 to 70 ml.g-r, the V60 value, which was reduced from 894 ml.L-1 to 427 ml.L-1, and the zeta poten- tial （0, which was reduced from -19.81 mV to -14.29 mV. The results indicate that the addition of this synthetic zeolite to activated sludge, as an additional waste management practice, has a positive impact on both ammonium removal and sludge settleability.展开更多
A recent study conducted on the four activated systems serving the surrounding communities in the Northern Gauteng revealed the failure of three of these wastewater treatment plants to remove enteric pathogenic bacter...A recent study conducted on the four activated systems serving the surrounding communities in the Northern Gauteng revealed the failure of three of these wastewater treatment plants to remove enteric pathogenic bacteria and protozoan parasites such as Cryptosporidium and Giardia spp. To determine the factors involved in the inadequate performance of the plants, the following parameters were considered： the design characteristic of the plants, the microbiological structure and the physical characteristics of the plants. The results revealed that higher than optimal influent loadings and inadequate aeration systems, observed in Baviaanspoort, Refilwe and Rayton Water Care Works （WCW） increased the composition of filamentous bacteria in flocs and decreased the diversity of protozoan species in the sludge. Sequentially, these resulted in the poor settling properties of the sludge at these plants. However, Zeekoegat WCW showed optimum influent loads and adequate aeration systems. This maintained balance in the microbial community, resulting in good clarification of the sludge.展开更多
文摘Biochar is a massively produced by-product of biomass pyrolysis to obtain renewable energy and has not been fully used. Incomplete separation of sludge and effluent and insufficient denitrification of sewage are two of main factors that influence the efficiency of activated sludge process. In this work, we proposed a new utilization of biochar and investigated the effect of biochar addition on the performance of settleability and denitrification of activated sludge. Results show that the addition of biochar can improve the settleability of activated sludge by changing the physicochemical characteristics of sludge （e.g., flocculating ability, zeta-potential, hydrophobicity, and extracellular polymeric substances constituents）. Moreover, the dissolved organic carbon released from biochar obtained at lower pyrolysis temperature can improve the nitrate removal efficiency to a certain extent.
基金Supported by the Spanish Ministry of Science and Innovation,under the project FOXMORE(CTM2006-05114)
文摘Municipal wastewater treatment plants typically exhibit two classic problems： high ammonium concen- tration in water after conventional biological treatment and, in some cases, poor activated sludge sediment ability. Potential solutions to these problems were investigated by adding a synthetic zeolite obtained from coal fly ash to different steps of activated sludge treatment. The experimental results for ammonium removal fit well with the theoretical adsorption isotherms of the Freundlich model with a maximum adsorption capacity of 13.72 mg.g-＇. Utiliza- tion of this kind of zeolite to improve activated sludge sediment ability is studied for the first time in this work. It is found that the addition of the zeolite （1 g. L-1） to an activated sludge with settling problems significantly enhances its sediment ability and comoact ability. This is confirmed by the sludge volume index （SVI）, which was reduced from 163 ml.g-1 to 70 ml.g-r, the V60 value, which was reduced from 894 ml.L-1 to 427 ml.L-1, and the zeta poten- tial （0, which was reduced from -19.81 mV to -14.29 mV. The results indicate that the addition of this synthetic zeolite to activated sludge, as an additional waste management practice, has a positive impact on both ammonium removal and sludge settleability.
文摘A recent study conducted on the four activated systems serving the surrounding communities in the Northern Gauteng revealed the failure of three of these wastewater treatment plants to remove enteric pathogenic bacteria and protozoan parasites such as Cryptosporidium and Giardia spp. To determine the factors involved in the inadequate performance of the plants, the following parameters were considered： the design characteristic of the plants, the microbiological structure and the physical characteristics of the plants. The results revealed that higher than optimal influent loadings and inadequate aeration systems, observed in Baviaanspoort, Refilwe and Rayton Water Care Works （WCW） increased the composition of filamentous bacteria in flocs and decreased the diversity of protozoan species in the sludge. Sequentially, these resulted in the poor settling properties of the sludge at these plants. However, Zeekoegat WCW showed optimum influent loads and adequate aeration systems. This maintained balance in the microbial community, resulting in good clarification of the sludge.
