Applied microbiology 10/1964; 12:412-7.
Source: PubMed

ABSTRACT Over 300 bacterial strains were isolated from seven samples of activated sludge by plating on sewage agar. Gram-negative bacteria of the genera Zoogloea and Comamonas predominated. Many isolates (51%) showed sudanophilic inclusions of poly-beta-hydroxybutyric acid, whereas 34% accumulated iodophilic material on media containing starch. A large number required either vitamins or amino acids, or both, for growth. None of the isolates tested for their ability to bring about changes in autoclaved sewage produced an effluent comparable in quality to the activated sludge control, although the Zoogloea did produce activated sludgelike flocs. A study of 150 bacterial strains isolated from raw sewage revealed that they differed from the sludge isolates in several respects. Coliforms, which constitute nearly a quarter of the sewage isolates, were rarely encountered in sludge.

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    ABSTRACT: Many studies have described alternatives to the BOD5 standard method, with substantial decreases in incubation time observed. However, most of these have not maintained the features that make the BOD5 assay so relevant - a high level of substrate bio-oxidation and use of wastewater treatment plant (WWTP) sludge as the biocatalyst. Two recently described ferricyanide-mediated (FM)-BOD assays, one for trade wastes and one for WWTP influents and treated effluents, satisfy these criteria and were investigated further here for their suitability for use with diverse biocatalysts. Both FM-BOD assays responded proportionately to increasing substrate concentration with sludges from 11 different WWTPs and temporally (months to years) using sludges from a single WWTP, confirming the broad applicability of both assays. Sludges from four WWTPs were selected as biocatalysts for each FM-BOD assay to compare FM-BOD equivalent values with BOD5 (three different sludge seeds) measurements for 12 real wastewater samples (six per assay). Strong and significant relationships were established for both FM-BOD assays. This study has demonstrated that sludge sourced from many WWTPs may be used as the biocatalyst in either FM-BOD assay, as it is in the BOD5 assay. The industry potential of these findings is substantial given the widespread use of the BOD5 assay, the dramatically decreased incubation period (3-6h) and the superior analytical range of both assays compared to the standard BOD5 assay.
    Talanta 07/2014; 125:293-300. DOI:10.1016/j.talanta.2014.03.004 · 3.51 Impact Factor
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    ABSTRACT: Combined anaerobic/aerobic processes for municipal wastewater treatment is quite recent; the studies developed have shown these processes are feasible for the removal of organic, nutrient substances and reduction of sludge produced. Previous studies developed at the Marrero Wastewater pilot plant (fully aerobic system) revealed that the minimum solids contact chamber hydraulic residence (HRT) time in which bioflocculation occurs satisfactorily (effluent SS concentrations < 20 mg/L) is 15 min; however, in the combined anaerobic/aerobic system HRT< 100 minutes resulted in poor floc settling properties and turbid supernatants. Exocellular polymeric substances (EPS) have been found to be the key factor for bioflocculation to occur. Past studies in fully aerobic pilot plant demonstrated that the concentration of EPS increased with mixed liquor concentration and solids retention time. The main purpose of this research is to determine the effect of mixed volatile suspended solids(MLVSS), solids retention time(SRT), and dissolved oxygen(DO) in the production of EPS in the combined anaerobic/ solids contact chamber and its relationship with settling parameters. To carry out the objectives of this investigation three experimental phases were developed : 1) The MLVSS concentration was varied between 1000-4000 mg/l, keeping the SRT and DO as constant as possible 2) The SRT was changed between 2-8 days, keeping the MLVSS concentration between 1500-3500 mg/l and DO between 2-3 mg/l 3) the DO concentration was varied between 0-5mg/l. For a DO of zero, EPS were extracted from the sludge produced in the anaerobic reactor. Analysis of the data showed that the combined system proved to be unstable producing unexpected results such as no clear relationship between MLVSS and EPS. For a DO of zero, no EPS are produced and no flocculation takes place; therefore, effluents with poor quality can be expected from anaerobic treatment units. To meet secondary effluent standards in aeration chamber, capable of promoting the transformation from anaerobic to aerobic biota, and the generation of EPS, high SRT and HRT is required. Under these conditions the system anaerobic/solids contact chamber has an excellent potential for providing secondary treatment for municipal wastewater; nevertheless, the system is not as stable as the conventional aerobic one and bulking problems are common and difficult to content.
  • Critical Reviews in Environmental Science and Technology 01/1993; 23(1):79-117. DOI:10.1080/10643389309388442 · 3.24 Impact Factor


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