Composition and Distribution of Extracellular Polymeric Substances in Aerobic Flocs and Granular Sludge

Extracellular polymeric substances (EPS) were quantified in flocculent and aerobic granular sludge developed in two sequencing batch reactors with the same shear force but different settling times. Several EPS extraction methods were compared to investigate how different methods affect EPS chemical characterization, and fluorescent stains were used to visualize EPS in intact samples and 20-µm cryosections. Reactor 1 (operated with a 10-min settle) enriched predominantly flocculent sludge with a sludge volume index (SVI) of 120 ± 12 ml g–1, and reactor 2 (2-min settle time) formed compact aerobic granules with an SVI of 50 ± 2 ml g–1. EPS extraction by using a cation-exchange resin showed that proteins were more dominant than polysaccharides in all samples, and the protein content was 50% more in granular EPS than flocculent EPS. NaOH and heat extraction produced a higher protein and polysaccharide content from cell lysis. In situ EPS staining of granules showed that cells and polysaccharides were localized to the outer edge of granules, whereas the center was comprised mostly of proteins. These observations confirm the chemical extraction data and indicate that granule formation and stability are dependent on a noncellular, protein core. The comparison of EPS methods explains how significant cell lysis and contamination by dead biomass leads to different and opposing conclusions

Swirl Flow Bioreactor coupled with Cu-alginate beads: A system for the eradication of Coliform and Escherichia coli from biological effluents.

It is estimated that approximately 1.1 billion people globally drink unsafe water. We previously reported both a novel copper-alginate bead, which quickly reduces pathogen loading in waste streams and the incorporation of these beads into a novel swirl flow bioreactor (SFB), of low capital and running costs and of simple construction from commercially available plumbing pipes and fittings. The purpose of the present study was to trial this system for pathogen reduction in waste streams from an operating Dewats system in Hinjewadi, Pune, India and in both simulated and real waste streams in Seattle, Washington, USA. The trials in India, showed a complete inactivation of coliforms in the discharged effluent (Mean Log removal Value (MLRV) = 3.51), accompanied by a total inactivation of E. coli with a MLRV of 1.95. The secondary clarifier effluent also showed a 4.38 MLRV in viable coliforms during treatment. However, the system was slightly less effective in reducing E. coli viability, with a MLRV of 1.80. The trials in Seattle also demonstrated the efficacy of the system in the reduction of viable bacteria, with a LRV of 5.67 observed of viable Raoultella terrigena cells (100%)

Sustainable water management in rural and peri-urban areas: what technology do we need to meet the UN Millennium Development Goals?

Installation of advanced urban water management systems is one of the most important first steps in the attempt to overcome poverty on earth, outbreak of diseases, crime and even terrorism. Because world wide application of traditional water supply, sewerage and wastewater treatment technology requires financial resources which are basically not available within a reasonable short time frame novel solutions must be found, developed and implemented. The combination of high-tech on-site treatment of the various waste streams generated in households, enterprises and industrial sites, and reuse of the valuable materials obtained from the treatment plants, including the purified water, is one of the options which is investigated by various groups of researchers and technology developers, nowadays. This concept may help meeting the UN Millennium Development Goals, provided people are ready to accept this new way of dealing with household wastes. Education is necessary to build up the foundation which modern water technology can be based upon. In parallel, tailored modifications are to be considered to satisfy the specific demands of local communities. In this context, female participation appears to be extremely important in the decision making process. Keywords UN Millennium Development Goals; urban water management; flushing sewer concept; source separation; female involvemen

Application of FISH and CLSM/Image Analysis for Microbial Examination in Biological Wastewater Treatment in China

Water in China' brings together a number of articles which describe the current situation in China with respect to surface water quality and wastewater treatment, and provide results of specific research projects, leading the way to a China-specific up-to-date water treatment technology

The effect of intermittent feeding on aerobic granule structure

Self-immobilized biofilms, or aerobic granules without the addition of carrier material, have only been reported in one suspended growth system, the Sequencing Batch Reactor (SBR) with a very short fill time (dump fill). The SBR utilizes intermittent feeding which creates a period of high load followed by starvation (often referred to as feast-famine). In this experiment, three identical SBRs were operated with different feeding conditions to determine the role of feast-famine on granule formation. All three SBRs were operated with a total volumetric load of 2.4 kg/m3.d. The 90 minute Fill phase was altered for each reactor, providing an increasing time of Aerated Fill. A dump fill condition was applied for one reactor, while the other two reactors were aerated for different times during Fill, resulting in a smaller COD load at the beginning of each React phase. Aerobic granules formed in all reactors, but the structural properties and content of filamentous organisms were clearly dependent on a high feast condition. Only the reactor with dump fill formed compact, stable granules. It is concluded that intermittent feeding associated with the SBR affects the selection and growth of filamentous organisms and has a critical role in granule structure and composition

Using quantitative real-time PCR to determine the hygienic status of cattle manure

We developed a suitable system of DNA extraction and real-time quantitative polymerase chain reaction (qPCR) for the specific and sensitive quantification of pathogens and other relevant (indicator) organisms in recalcitrant material such as cattle manure. PCR inhibition by coextraction of humic compounds was minimized in this system, resulting in detection sensitivity of one target DNA copy per reaction well. Data from qPCR analysis for Escherichia coli agreed with cultivation based results, but orders of magnitude more fecal enterococci, Enterobacteriaceae and Campylobacter jejuni, were determined by qPCR than by cultivation. These bacteria may have been in a potentially hazardous active but non-cultivable state. The qPCR system is much less time consuming than conventional cultivation, highly specific, can detect non-cultivable organisms, provides high measurement throughput, and is cost attractive. It should be considered as an alternative in various application areas for (prescribed routine) cultivation based assays, e.g. for biosafety and hygiene monitoring