The in situ physiology of "Nostocoida limicola" II, a filamentous bacterial morphotype in bulking activated sludge, using fluorescence in situ hybridization and microautoradiography

The in situ physiology of the actinobacterial bulking and foaming filamentous bacterium "Nostocoida limicola" II was studied by fluorescence in situ hybridization/microautoradiography. Substrate assimilation patterns of pure cultures of this bacterium were different to those seen in activated sludge biomass samples. There was no evidence to suggest that "N. limicola" II preferred hydrophobic substrates, but evidence was produced to support the view that it is metabolically active under anaerobic conditions in activated sludge.

Characterization of the extracellular polymeric substances and microbial community of aerobic granulation sludge exposed to cefalexin

This study characterizes the extracellular polymeric substances and bacterial community composition of aerobic granules exposed to cefalexin (CLX). The presence of CLX potentially decreases granular stabilities, resulting in a lowered granule diameter. Chemical oxygen demand and NH4+-N removal efficiencies were slightly decreased and the denitrification process was inhibited with CLX addition. Extracellular polymeric substance contents were significantly increased in aerobic granules exposed to CLX. The shifts of fluorescence intensities and peak locations in 3D-EEM fluorescence spectra indicated changes of EPS components. High-throughput sequencing analysis showed aerobic granules with CLX addition in synthetic wastewater had superior diversity of microbial species, and this was the reason that the level and components of EPS changed. The species richness for bacteria was increased from 341 to 352, which was revealed by Chao1. The Shannon index of diversity rose slightly from 3.59 to 3.73 with CLX addition. The abundance of Proteobacteria significantly decreased, while the abundance of Bacteroidetes and Chloroflexi underwent a highly significant increase in aerobic granules exposed to CLX.

Anaerobic treatment of juice and fruit-processing effluents

Effluents from the juice and fruit processing industries have high organic matter content. Discharge of these effluents without appropriate treatment would therefore have a negative impact on the environment. High organic contents and low contamination levels make such effluents suitable for biological treatment, especially anaerobic digestion. In the latter process, significant amounts of digester gas can be produced, turning a waste stream into a source of renewable energy that can be used for electricity and heat production, leading to financial benefits.This paper investigates the feasibility of anaerobic digestion and the gas generation potential of five different effluents from the carrot-juice, orange-juice and sultana processing industries. Benefits are assessed in terms of digester gas production and organic matter reduction. The results show that the specific gas production ranges between 665 and 860 m3 per tonne of effluent treated (as organic dry matter). Furthermore, nearly 100% of the organic matter is converted into gas in the case of the carrot- and orange-juice processing residues, while a 84.5% reduction of the organic matter was found to be achievable in the case of the sultana wastes. While these results are promising, further testing will be required to validate them in a larger scale.

Anaerobic degradation of organic materials - significance of the substrate surface area

In anaerobic degradation of substrates containing mainly particulate organic matter, solids hydrolysis is rate-limiting. In these investigations, the particle size of various substrates was reduced by comminution to support hydrolysis. Two positive effects of comminution were observed. For substrates with high fibre content, which are particularly resistant to biodegradation, a significant improvement of the degradation degree was observed as a result of comminution. Secondly, for all substrates tested, and particularly for those rich in fibres, the degradation rate of comminuted samples was significantly higher. The first reason for both effects is an increase of the sample surface area. Several methods for measuring the specific surface area of organic materials, including particle size analysis, Nitrogen-adsorption and enzyme adsorption, were used and compared for the purpose of this study, where the surface area accessible to microbial enzymes is critical. The significance of the surface area in anaerobic degradation of particulate substrates was investigated through a kinetic model where the hydrolysis rate was based on the sample surface area. Good agreements were obtained between model and experiments carried out with samples of various specific surface areas. These results reinforced the significance of the sample surface area in anaerobic degradation processes. However, other effects of comminution responsible for the increased degradation degree and degradation rate were identified and discussed. These include: the increase of dissolved compounds due to cell rupture, exposition of surface areas previously inaccessible for microbial degradation, and alteration of the sample structure such as the lignin-cellulose arrangements.

How world's best public relations practice was not, but might have been achieved, in respect of a "biosolids" (stabilised sewage sludge) project

This is a case study which criticises the way a water authority has been trying to introduce “biosolids” (stabilised sewage sludge) projects. Two proposed projects have been abandoned after outcry by communities neighbouring earmarked sites. At the time of writing a third project was going ahead. This local scale clash reflects contests which are cropping up globally as water authorities are restricted in their use of land or sea dumping and ordered to introduce environmentally sustainable practices. The case study ends with a discussion of a strand of cultural theory which might have given the water authority a better understanding of the public issues involved. The article concludes that understanding cultural theory might assist organisations achieve world best practice in public relations when they face some of the pressing environmental and safety concerns of the 21st century.

Anaerobic capacity and adaption of endurance-trained runners

Demonstrates that anaerobic capacity, using the accumulated oxygen deficit technique, can be measured rapidly and with a high degree of precision, however significant difficulties remain to be addressed. Significant further insights into some of the underlying cellular mechanisms associated with increases in anaerobic capacity were also obtained.

Modelling based design of a pilot-scale membrane bioreactor for combined nutrient removal from domestic wastewater

A three stage-treatment of domestic wastewater including anaerobic, anoxic and aerobic phases is employed in this study while a clarifier unit is replaced with a submerged membrane in the aerobic unit. The effects of operational parameters on the performance of a pilot scale submerged membrane bioreactor (SMBR) namely hydraulic retention time (HRT), ratio of return activated sludge (QRS), ratio of internal recycle (QIR), solid retention time (SRT) and dissolved oxygen (DO) are evaluated by simulations, using a hybrid model composed of TUDP model, oxygen transfer model, biofouling model due to extra-cellular polymeric substances (EPS) and turbulent shear model. The results showed that anaerobic HRT of 3 hours, anoxic HRT of 6 hours, QRS of 20% and QIR of 300 % are satisfactory in obtaining a high removal efficiency (>90%) of COD, NH4-N, P04-P as well as a less sludge production. An increase of sludge production causes an increase in EPS, which fouls the membrane surface and increase the cleaning cycle of membrane. Operation of 5MBR system at 2 mg/I of DO and 30 days of SRT can extend the membrane cleaning cycle dramatically. The membrane cleaning cycle however is strongly dependent on the initial and terminal specific fluxes and displays inverse power relationships to those fluxes.