Application Of The Combined Anaerobic-aerobic Bio-filter With Novel Ceramics For Tetracycline Wastewater Treatment

In this study, two novel light ceramic media based on coal cinder and sludge were used in the combined up-flow anaerobic bio-filter (UAF) and up-flow biological aerated filter (UBAF) system to treat the synthetic tetracycline (TET) wastewater. The characteristics of two new ceramics were investigated in this paper to detect their potential advantage for TET wastewater treatment. Then the influences of organic matter concentration, TET concentration and the low temperature (<16℃) on the removal of wastewater were studied. In the stable operation, the microbial species, ratio, microbial diversity and the functional profiles in the UAF-UBAF system were explored to study the degradation mechanism of different organics in TET wastewater. In the end, the iron-carbon micro-electrolysis technology was added. The optimum operation conditions of the electrobath reactors with novel coal ash ferric-carbon ceramic fillers were detected.To be specific, the physical properties of two novel light ceramics were totally conformed to the national lightweight filler application standard. They have low bulk and grain density, rough surface, stable crystal components and high total porosities. The start-up periods of UAF and UBAF were shortened to 42 and 10 days with the application of two novel ceramics. Furthermore, the UAF-UBAF system showed high organic load, high processing efficiency, strong shock and tetracycline resistance when it was compared with conventional reactors. Moreover, the low temperature did not affect the system. When influent COD and NH4-N were 4000 and 200 mg/L, the influent tetracycline of 45 mg/L was the best operating conditions. In this stage, the total removal rates of COD, NH4-N and TET could reach to 97%,99% and 89%.Microbial species, functional communities and microbial diversity were tested to explain the good performance of UAF-UBAF for treating TET wastewater. The main degradation process of pollutants took place at 0-80 cm height. As reactor height increased, the EPS decreased. The concentration of EPS in UAF was more than that in UBAF for the same height. Comamonadaceae, Thauera and Sinobacteraceae were the main bacteria that degraded tetracycline due to the measurement of dominant species. For UAF, hydrolysis mainly happened at low reactor height while acetogenesis and acidification mainly took place at high reactor height. In addition, the dominant species changed from anaerobic bacteria to aerobic bacteria in UBAF. With the gradual biodegradation of tetracycline, the microbial diversity became richer and richer.In order to improve the abilty of UAF-UBAF for the TET degradation further and reduce the development of antibiotic-resistant bacteria, application of novel sintering ferric-carbon ceramics (SFC) and sintering-free ferric-carbon ceramics (SFFC) based on coal ash and scrap iron for pretreatment of tetracycline (TET) wastewater were investigated. Physical and chemical properties were studied to explore the application of novel ceramics in micro-electrolysis reactors. The influences of influent pH, hydraulic retention time (HRT) and air-water ratio (A/O) on the removal of tetracycline were also studied. The results showed that the properties of SFC and SFFC conformed to national standard and they were suitable for application in micro-electrolysis reactors. The optimum conditions of SFC reactor were pH of 3, HRT of 7 h and A/O of 10. For SFFC reactor, the optimum conditions were pH of 2, HRT of 7 h and A/O of 15. In general, the removal efficiency of SFC reactor for TET wastewater was better than that of SFFC reactor. However, the harden resistance and recyclability of SFFC were better than that of SFC. Furthermore, the biodegradability of TET wastewater was improved greatly after micro-electrolysis pretreatment for both SFC and SFFC reactors, which was better for the subsequent treatment of UAF-UBAF system.Two novel ceramic materials based on sludge and coal cinder were prepared; The optimum operating conditions of UAF-UBAF system was determined; The degradation mechanism of tetracycline wastewater were described in detailed in this research. A novel material and a new technology were provided for the treatment of tetracycline wastewater in this particle. This particle was also meaningful for the resource utilization of sludge and coal cinder.