Case study of the in-situ restoration of black-odorous water by combined process of forced aeration and biological contact oxidation

Abstract

Abstract Black and odorous water bodies are an extreme phenomenon that impair ecological integrity, adversely affect the lives of residents and the town's image, and cause unpleasant sensory experiences. Herein, we consider a black and smelly river in Heshan City, Guangdong Province, as a case study. The proposed comprehensive governance process combines the use of pollution control and interception, sediment remediation, aeration oxygenation, a high-efficiency biological contact oxidation/denitrification pond, and ecosystem construction. The project operation results showed that the combined process can effectively improve water quality. The water quality of the river improved to the Class V standard. All indicators met the requirements of the ‘China Surface Water Environmental Quality Standard’ (GB3838-2002). River water quality indicators, monitored for four months, revealed that water transparency and dissolved oxygen increased by 5.9 times and 24.5 times, respectively. Dichromate index (CODcr), total phosphorus (TP), and ammonia nitrogen (NH3-N) were reduced by 5.8, 4.17, and 5.17 times when compared to the values observed before treatment. The black-odor and eutrophication of the river were successfully eliminated, and the water quality improved significantly. In general, the combined process exhibits a high technical feasibility for implementation, providing a specific reference value for the treatment of black and odorous water bodies in urban settings.