Effect of novel sludge and coal cinder ceramic media in combined anaerobic–aerobic bio-filter for tetracycline wastewater treatment at low temperature

• Sludge and coal cinder mixed with straw and clay were used to make two ceramics.
• Novel ceramics made UAF and UBAF had shorter start-up periods of 42 and 10 days.
• The combined UAF–UBAF system was operated at low temperature (16 °C).
• The system presented high processing efficiency and organic load.
• The system showed strong shock resistance and tetracycline resistance.

Two novel ceramic media were prepared by sludge, coal cinder and straw. Their characteristics such as physical property, total porosities and crystal components were studied. Moreover, their application on the combined up-flow anaerobic bio-filter (UAF) and up-flow biological aerated filter (UBAF) system to treat the synthetic wastewater containing tetracycline (TET) were studied at low temperature of 16 °C. To be specific, first, chemical oxygen demand (COD) and ammonia (NH4-N) were measured to determine the start-up time. Then in the steady operation stage, influence of nitrogen and TET on the removals of COD, NH4-N, total nitrogen, total phosphorus and TET were investigated. Results showed that two new ceramics possessed high total porosity, roughness surface, low bulk and grain density. Due to the novel ceramics fillers, the start periods of the UAF and UBAF were shortening to 42 and 10 days. Moreover, compared to conventional reactor, the new system had advantages of high processing efficiency, high organic load, strong shock and tetracycline resistance. When original influent COD, NH4-N and TET were 4000, 200 and 45 mg/L, the total COD, NH4-N and TET reductions could reach to 97%, 99% and 89%. Furthermore, the low temperature did not influence the system.