Ex-situ treatment of black-odorous sediment by combining activated sludge and advanced oxidants

Abstract Treating sediment is essential for restoring black-odorous water because it holds many pollutants. High-efficiency chemical methods and low-cost biological methods are usually used for the ex-situ treatment of black-odorous sediment. However, the cost of chemical treatments is high and biological treatment needs a long period. This study involved a combined process coupling pre-biological treatment with post-chemical treatment to treat the raw black-odorous sediment. Two types of waste activated sludge from a secondary sedimentation tank (SST) and a digestion tank (DT) were used for the pre-biological treatment, and hydrogen peroxide was used for post-chemical treatment. Sediment treatment was improved by the combination process, with the SST + 10 mL H2O2/(L sediment) treatment working the optimal. The removal of total nitrogen and total phosphorus reached approximately 71.2% and 52.2%, respectively, and the removal of water and organics reached 29.3% and 17.6%, respectively. MiSeq sequencing found that adding SST sludge improved the microbial community diversity of the sediment, and obviously increased the abundance of microorganisms related to nitrification (such as Nitrospira) and sulfur metabolism (such as Sulfurovum) to 0.6% and 1.2%, respectively. This promoted treatment performance. However, the microbial diversity was reduced after adding the oxidant. This study identified a cost-effective process for treating black-odorous sediment, greatly decreasing the treatment period and cost.