Abstract
Activated sludge bulking is easily caused in winter, resulting in adverse effects on effluent treatment and management of wastewater treatment plants. In this study, activated sludge samples were collected from different wastewater treatment plants in the northern Xinjiang Uygur Autonomous Region of China in winter. The bacterial community compositions and diversities of activated sludge were analyzed to identify the bacteria that cause bulking of activated sludge. The sequencing generated 30087–55170 effective reads representing 36 phyla, 293 families, and 579 genera in all samples. The dominant phyla present in all activated sludge were Proteobacteria (26.7–48.9%), Bacteroidetes (19.3–37.3%), Chloroflexi (2.9–17.1%), and Acidobacteria (1.5–13.8%). Fifty-five genera including unclassified_f_Comamonadaceae, norank_f_Saprospiraceae, Flavobacterium, norank_f_Hydrogenophilaceae, Dokdonella, Terrimonas, norank_f_Anaerolineaceae, Tetrasphaera, Simplicispira, norank_c_Ardenticatenia, and Nitrospira existed in all samples, accounting for 60.6–82.7% of total effective sequences in each sample. The relative abundances of Saprospiraceae, Flavobacterium, and Tetrasphaera with the respective averages of 12.0%, 8.3%, and 5.2% in bulking sludge samples were higher than those in normal samples. Filamentous Saprospiraceae, Flavobacterium, and Tetrasphaera multiplied were the main cause for the sludge bulking. Redundancy analysis (RDA) indicated that influent BOD5, DO, water temperature, and influent ammonia had a distinct effect on bacterial community structures.
Highlights
Activated sludge process has been extensively used in industrial and domestic wastewater treatment because of its high microbial diversity and activity, resulting in the removal of most organic pollutants and nutrients [1]
Fifty-five genera, which accounted for 60.6–82.7% of the classified sequences and included the unclassified f Comamonadaceae, norank f Saprospiraceae, Flavobacterium, norank f Hydrogenophilaceae, Dokdonella, Terrimonas, norank f Anaerolineaceae, Tetrasphaera, Simplicispira, norank c Ardenticatenia, and Nitrospira genera were generally shared by all samples
36 phyla, 293 families, and 579 genera were found in activated sludge samples from wastewater treatment plants (WWTPs) of Xinjiang in winter
Summary
Activated sludge process has been extensively used in industrial and domestic wastewater treatment because of its high microbial diversity and activity, resulting in the removal of most organic pollutants and nutrients [1]. The biological community of activated sludge has a large biological diversity and contains a variety of viruses, bacteria, protozoa, fungi, algae, and metazoan. In this complex ecosystem, bacteria typically account for 95% of the total number of microbes and play a crucial part in wastewater treatment [3]. Bulking sludge due to overgrowth of filamentous bacteria and/or Zoogloea organisms has a significant influence on the performance of the activated sludge system as it can result in poor settling and poor compaction [4]. Sludge bulking can occur at low temperature, resulting in adverse effects on effluent treatment [6]. Sludge bulking in winter caused by low temperature is the focus of the study
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