In biological wastewater treatment technologies the majority of systems are based on activated sludge technology. In these systems the population structure and dynamics of the activated sludge microbial community is largely governed by indirect regulatory mechanisms, such as aerated/nonaerated reactors, reactor configurations and sludge recycling ratios. The build-up of activated sludge flocs (...

in this study, the bacterial diversity in the activated sludge system of a full-scale municipalwastewater treatment plant in dubai was monitored over a period of one year using ribosomal rna (rrna)targeted oligonucleotide probes for a defined phylogenetic group of bacteria by the fluorescence in situhybridization (fish) technique. the largest fraction of the bacterial community in the sludge sa...

Oxic-settling-anaerobic process (OSA) was known as a cost-effective way to reduce the excess sludge production with simple upgrade of conventional activated sludge process (CAS). A low oxidation-reduction potential (ORP) level was the key factor to sludge decay and lysis in the sludge holding tank of the OSA process. However, the ORP control with nitrogen purge or chemical dosing in the OSA pro...

The bacterial community structures of phosphate- and non-phosphate-removing activated sludges were compared. Sludge samples were obtained from two sequencing batch reactors (SBRs), and 16S rDNA clone libraries of the bacterial sludge populations were established. Community structures were determined by phylogenetic analyses of 97 and 92 partial clone sequences from SBR1 (phosphate-removing slud...

An analytical method has been developed and applied to determine the concentrations of the nonionic alkylphenol polyethoxylate surfactants and their metabolites, alkylphenoxy carboxylates and alkyphenols, in sewage sludges. The compounds were extracted with methanol/acetone (1:1 v/v) from sludge, and concentrated extracts were cleaned by silica solid-phase extraction prior to determination by l...

-An objective index, the Sludge Biotic Index (SBI), based on the microfauna associated with activated-sludge mixed liquor, has been devised to monitor activated-sludge plant performance. The proposed method makes it possible to define the biological quality of the sludge using numerical values (biotic index) of 0-10, and to group SBI values into four quality classes. The method is based on two ...

Volatile organic compound emissions from painting operations are of primary concem in the automotive industry and require costly control measures using vapor-phase activated-carbon adsorption. At Ford Research Laboratory, Dearborn, Michigan, a process modification has been proposed as a supplemental or an alternative control measure to convert an existing paint-sludge pit, part of a spray-booth...

the aim of this study was to determine the feasibility of coupling an electrochemical process with a biological treatment in order to degrade phosmet, an organophosphorous pesticide. the absence of biodegradability of phosmet by pseudomonas fluorescens and activated sludge was verified in our operational conditions. so, a conventional biological treatment is not appropriate for phosmet polluted...

Anaerobically treated sewage sludge was found to contain extraordinarily high concentrations of 4-nonylphenol, a metabolite derived from nonionic surfactants of the nonylphenol polyethoxylate type. Concentrations in activated sewage sludge, in mixed primary and secondary sludge, and in aerobically stabilized sludge were substantially lower, suggesting that the formation of 4-nonylphenol is favo...