SummaryEnhanced biological phosphorus removal (EBPR) relies on diverse but specialized microbial communities to mediate the cycling and ultimate removal of phosphorus from municipal wastewaters. However, little is known about microbial activity and dynamics in relation to process fluctuations in EBPR ecosystems. Here, we monitored temporal changes in microbial community structure and potential activity across each bioreactor zone in a pilot-scale EBPR treatment plant by examining the ratio of small subunit ribosomal RNA (SSU rRNA) to SSU rRNA gene (rDNA) over a 120 day study period. Although the majority of operational taxonomic units (OTUs) in the EBPR ecosystem were rare, many maintained high potential activities based on SSU rRNA : rDNA ratios, suggesting that rare OTUs contribute substantially to protein synthesis potential in EBPR ecosystems. Few significant differences in OTU abundance and activity were observed between bioreactor redox zones, although differences in temporal activity were observed among phylogenetically cohesive OTUs. Moreover, observed temporal activity patterns could not be explained by measured process parameters, suggesting that other ecological drivers, such as grazing or viral lysis, modulated community interactions. Taken together, these results point towards complex interactions selected for within the EBPR ecosystem and highlight a previously unrecognized functional potential among low abundance microorganisms in engineered ecosystems.
This paper examines the role of short-chain volatilc fatty acids In the cxcess biological phosphorus rcmoval mechanism of the activated sludge process. The effectiveness of various substrate additions in inducing phosphorus removal was investigated through a series of laboratory and pilot-scalc experiments. Phosphorus releasc and substratc uptake both take placc in the anaerobic zone of the process and thcre appears to bc an exchange phenomenon that occurs bctwccn the two molecules. The system phosphorus removal of the process is ~mprovcd by the addition of sodium acetate to the anaerobic zone. Lt is important that the zone receives no incoming nitrate, as the added substratc will be oxidizcd in the denitrification reaction, rendering it unavailable for the phosphorus removal mechanism. Acetate and propionatc, the two substrates that are most cffcctive in inducing anaerobic phosphorus release, can be generated on-site at a treatment plant by primary sludge fcrmcntation in concentrations sufficient to significantly cnhancc the phosphorus removal characteristics of thc process.Key words: biological phosphorus removal, short-chain volatilc fatty acids, phosphorus rclcase, substrate utilization, primary sludge fermentation.Cette publication examine le r81e des acides gras volatils de chaine court dans Ic mecanisme dc ddphosphoration biologique des eaux usCes par boues activCes. L'efficacitC de divers substrats a stimuler le retrait du phosphorc en solution fut etudie i travers une strie d'cxpCriences aux Cchelles laboratoire et pilote. La liberation du phosphore dc meme quc I'absorption de substrats se situent dans la zone anaerobic du procddd ct il scmblcrait qu'un phenomenc d'Cchange s'cffectuc entrc les deux molCcules. L'efficacitC de dephosphoration biologique a ttt accru par I'ajout d'acdtatc dc sodium la zone ;~natrobie. I1 cst important que cette zone reqoive le minimum de nitrates puisqu'alors Ics substrats presents seraient utilists pour la dCnitrification plutBt que pour la dtphosphoration. Les deux substrats qui se sont rdvdlds Ctre les plus efficaces ii stimuler la libtration anaCrobie du phosphore sont I'acCtate et le propionate qui peuvcnt tous dcux etre produits par fermentation des boues primaires i I'usinc de traitement en concentration suffisante pour augmcnter de faqon significative la capacitC de dCphosphoration biologique par boues activees.Mots cle's: dCphosphoration biologique, acides gras volatils de chaine court, liberation de phosphore, consommation de substrats, fermentation dc boues primaires.Can. J. Civ. Eng. 13. 345-351 (1986)
Sludge minimization technologies have been available for several decades; however recent developments have brought some sludge minimization technologies to the forefront. All of the technologies utilize one or more of three basic approaches to minimize the amount of waste activated sludge produced by an activated sludge process: cell lysis, cyclic oxic environments, and long solids retention time. This paper will discuss the three basic mechanisms, will review the development of several sludge minimization technologies, and will report on the current viability of each technology as well as current research needs for each. 506 WEFTEC®.06
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.