Decentralised black water treatment by combined auto-thermal aerobic digestion and ammonia - A pilot study optimising treatment capacity

Evaluation of an anaerobic baffled reactor for pretreating black water: Potential application in rural China

Black water is highly concentrated human waste water but represents only a minor portion of domestic sewage. A modified type of anaerobic baffled reactor (ABR) was studied to assess its potential for pretreating black water in rural China. The classification of microbial structure was also investigated to confirm its potential in application. The structure of the ABR was modified according to demand for application in practice. A hydraulic retention time (HRT) of 48 h was chosen as the optimal HRT after comparison among 24 h, 36 h, 48 h, and 72 h. Under the 48 h HRT, the ABR achieved average removal efficiencies of 94.05% of chemical oxygen demand (COD), 28.78% of total nitrogen (TN), 14.21% of ammonium nitrogen (NH₄⁺-), and 32.54% of total phosphorus (TP) during 112 days of continuous operation. Samples from three different compartments were collected after 60-day continuous operation for bacterial and archaeal community investigation by 16S rRNA. Abundant degradation-related bacteria and methanogenic archaea were found in the ABR. The three samples had similar bacterial compositions at phylum, class, and genus levels, but the percentages of bacteria differed among the compartments. The distribution of archaea showed succession with the flow direction. In general, the ABR shows good performance under an HRT of 48 h and shows good potential for practical application.