The effect of anoxia and anaerobia on ciliate community in biological nutrient removal systems using laboratory-scale sequencing batch reactors (SBRs)

Abstract

Please cite this article as: Dubber, D., Gray, N.F. The effect of anoxia and anaerobia on ciliate community in biological nutrient removal systems using laboratory-scale sequencing batch reactors (SBRs), Water Research (2011Research ( ), doi: 10.1016Research ( /j.watres.2011 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. AbstractLittle is known about the effect of anaerobic and anoxic stages on the protozoan community in the activated sludge process and how this subsequently affects performance. Using a laboratory-scale BNR system the effect of different periods of anoxia on both the protozoan community and performance efficiency have been 15 examined. Four SBRs were operated at two cycles per day using a range of combined anoxic/anaerobic periods (0, 60, 120 to 200 min). Effluent quality (TOC, BOD, TP, TN, NH 4 -N, NO 3 -N and NO 2 -N), sludge settleability and ciliate community (species diversity and abundance) were analyzed over a periods of up to 24 days of operation. The species richness and total abundance of ciliates were found to decrease with longer 20 anoxic/anaerobic periods. Both, positive and negative significant correlations between the abundance of certain species and the period of anoxia was observed (e.g. Opercularia microdiscum, Epicarchesium granulatum), although other species (i.e. Acineria uncinata, Epistylis sp.) were unaffected by exposure to anoxia. In the laboratory-scale units, the 60 minute anoxic/anaerobic period resulted in good process performance (TOC and BOD 25 removal of 97 to 98% respectively), nitrification (80-90%), denitrification (52%) but poor levels of biological P removal (12%); with the protozoan community moderately affected but still diverse with high abundances. Increasing the length of anoxia to up to 200 min did not enhance denitrification although P removal rates increased to between 22-33%; however, ciliate species richness and total abundance both decreased and sludge 30 settleability became poorer. The study shows that activated sludge ciliate protozoa display a range of tolerances to anoxia that result in altered ciliate communities depending on the length of combined anoxic/anaerobic periods within the treatment process. It is recommended that anoxic/anaerobic periods should be optimized to sustain the protozoan community while achieving maximum performance and nutrient removal. 35

Relationship between protozoan and metazoan communities and operation and performance parameters in a textile sewage activated sludge system

“…The positive correlation between the DO and the abundance of Aspidisca cicada contradicts the findings of Cingolani et al (1992), Cingolani and Ciccarelli (1997), Nicolau et al (2005Nicolau et al ( , 2007 and Dubber and Gray (2011a) who stated that Aspidisca cicada showed a remarkable ability to survive in adverse conditions. The crawling ciliates, as a group, also showed a significant positive association with the DO of the mixed liquor (0.62; n = 35), and Vorticella microstoma indicated the lack of DO with a significant coefficient value of −0.51 (n = 35) which can be explained by its good resistance to the influence of anoxic environment and environmental changes (Madoni 1994;Esteban et al 1991;Lee et al 2004;Dubber and Gray 2011b). Testate amoebae and Arcella sp.…”

Comparative Genomic Analysis of Integral Membrane Transport Proteins in Ciliates

“…The paucity of polysaccharide export proteins could be explained if ciliates use exocytosis for polysaccharide export (Cheng and Hufnagel ; Gutierrez and Orias ; Turkewitz ). The studies reported here provide a wealth of novel information relevant to the ecology, evolution, physiology, and pathology of model ciliates and probably to the characteristics of many other ciliates of industrial and bioremediative importance (Dubber and Gray ; Gertler et al. ; Harikrishnan et al.…”

Revealing the Diversity and Quantity of Peritrich Ciliates in Environmental Samples Using Specific Primer-based PCR and Quantitative PCR

“…The peritrichs are responsible for water clarification by their bacterivory; hence, they are an ecologically important group in aquatic environments (9, 17, 29). The abundance of peritrichs is not often reported, and when planktonic, is difficult to interpret because they are either attached to algae in the plankton, or are in stages of telotroch, which are usually difficult to identify (see (28) and references therein).…”