| On the basis of the previous firing of novel ultra-lightweight sludge ceramics (ULSCs) by our research team, this study aimed to characterize the performance of these novel ceramsites, and make them act as filter media in treating wastewater by anaerobic biological filtration process. This paper mainly investigated their feasibility, applicability and potential advantage for wastewater treatment in the self-designed anaerobic bio-filter (AF). Moreover, under a particular phase microorganisms in this AF were observed and their cluster were analyzed, and modern molecular biology techniques (PCR-DGGE, clone and sequencing, etc.) were used to further investigate the dominant bacteria and their degradation mechanism in this particular phase.After a series of tests and operations, ULSCs have presented favorable performance. This novel ceramsite had good chemical stability. The bulk density, grain density and water absorption were respectively430.5kgm-3,817.2kgm-3and7.397wt%, which reached the national standard of ultra-lightweight ceramsites. The surface of this novel ULSCs was rough and with many small pores, meanwhile the cross-section was porous and with relatively large pores, which were advantageous for microorganisms attachment and immobilization. Regular shape, even size and proper voidage, made the water flow evenly and reactor clogging hard to be happened. The metal elements leaching test revealed that all the toxic metal contents in lixivium were much lower than the limits of national standards, and there also existed many nutrient elements which were favorable for microorganisms.This novel filter media was employed in the self-designed AF, and treated the synthetic wastewater that contained medium-high-strength organic matter. The start-up period was only45days, making the anaerobic start-up period greatly shortened. No clogging phenomenon was happened during the stable operation as long as one and a half year. Furthermore, this reactor system showed good ability to resist interferences and recover from them. Under low temperatures in winter, COD removal efficiency was still maintained more than90%. According to the determination of different influent COD concentration during five phases, and the relevant result of linearly increased COD removal rate in effluent, indicated that this AF packed with ULSCs had the prominent ability to removal COD, as well as the favorable potential to deal with much higher organic loadings.Under low temperatures in winter, molecular biology research about the microorganisms in long-time running AF was carried out. ULSCs with microorganisms were observed by scanning electron microscopy (SEM), and the results showed that a large amount of microorganisms which in different forms grew on the ULSCs, and some were covered by the thick extracellular polymers secreted by microorganisms. In addition, based on the PCR-DGGE analysis of biofilm and floc samples, it could come to the conclusion that many kinds of bacterial species were found during this period, and DGGE bands of biofilm samples were much more than that of floc samples. The result revealed that microbial community structure in biofilms was much richer than that in flocs. After cloning and sequencing, the result showed that large amounts of psychrophile and bacteria having degradability were detected in AF during this circumstance, explaining the phenomenon that such good performance achieved by AF when the temperature was low; moreover, a variety of different kinds of bacteria also demonstrated the diversity and adaptability of microorganism, showing that AF had favorable potential to treat various wastewater. |
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