Applicability of different textile materials in filtration process integrated with SBR for wastewater reuse in small settlements.

In recent years, research activities on water reuse applications have rapidly increased to manage natural water sources efficiently. Although these applications in centralized treatment systems can be effective, there are some drawbacks, including the economic factors for small settlements. In this study, a textile filtration unit with the integration of a sequencing batch reactor (SBR) was developed and different textile materials were used to enhance the treated effluent quality for reuse purposes. While the textile filtration unit alone could not effectively remove the pollutants, the removal efficiencies could not exceed 36% for COD and 50% for BOD5. However, SBR integration in to the filtration system improved the treated wastewater quality and COD and BOD5 reductions were obtained higher than 93%. Activated carbon coated cotton textile materials and activated carbon cloth, which was used for the first time for wastewater treatment, increased the treatment performance. In the filtration system, although the suspended solids were high in the SBR effluent, no clogging problem was observed even with higher operation times. This paper presents the research results on this textile filtration system, and experimental findings are discussed on the applicability of the system for small communities.

Reactor Designs and Configurations for Biological and Bioelectrochemical C1 Gas Conversion: A Review.

Microbial C1 gas conversion technologies have developed into a potentially promising technology for converting waste gases (CO2, CO) into chemicals, fuels, and other materials. However, the mass transfer constraint of these poorly soluble substrates to microorganisms is an important challenge to maximize the efficiencies of the processes. These technologies have attracted significant scientific interest in recent years, and many reactor designs have been explored. Syngas fermentation and hydrogenotrophic methanation use molecular hydrogen as an electron donor. Furthermore, the sequestration of CO2 and the generation of valuable chemicals through the application of a biocathode in bioelectrochemical cells have been evaluated for their great potential to contribute to sustainability. Through a process termed microbial chain elongation, the product portfolio from C1 gas conversion may be expanded further by carefully driving microorganisms to perform acetogenesis, solventogenesis, and reverse ß-oxidation. The purpose of this review is to provide an overview of the various kinds of bioreactors that are employed in these microbial C1 conversion processes.

Gasification of yeast industry treatment plant sludge using downdraft Gasifier.

Sludges produced in biological wastewater treatment plants have rich organic materials in their characteristics. Recent research studies have focused on the energy recovery from sludge due to its high organic content. The gasification process is a thermal conversion technology transforming the chemical energy contained in a solid fuel into thermal energy and electricity. The produced syngas as a mixture of CO, CH4, H2 and other gases can be used to generate electrical energy. The gasification of yeast industry sludge has been experimentally evaluated in a pilot scale downdraft-type gasifier as a route towards the energy recovery. The gasifier has 20 kg biomass/h fuel capacity. During gasification, the temperature achieved was more than 1,000°C in the gasifier, and then the syngas was transferred to the gas engine to yield the electricity. A load was connected to the grid box and approximately 1 kWh electrical power generation for 1 kg dry sludge was determined. The characteristics of residuals - ash, glassy material - were also analyzed. It was found that most of the heavy metals were fixed in the glassy material. Experimental results showed that the yeast industry sludge was an appropriate material for gasification studies and remarkable energy recovery was obtained in terms of power production by using syngas.

Aerobic and anaerobic bioprocessing of activated sludge: floc disintegration by enzymes.

Hydrolytic enzymes such as glucosidases, lipases, and proteases have an imperative function at the hydrolysis stage of complex organic structures in the degradation of biodegradable particulate organic matter. As a key factor, extracellular polymeric substances (EPS) control the extracellular hydrolytic enzymes in this degradation mechanism. A flocculated matrix of EPS bridging with bacteria holds back the dewaterability properties of the bioprocessed sludges. Disruption of the flocculated matrix leads to improved solubilization of sludge solids by attacking the hydrolytic enzymes to polymeric substances forming enzyme-substrate complexes. To determine the floc disintegration mechanisms by enzymes during aerobic and anaerobic bioprocessing of sludges, experimental data obtained from three aerobic digesters and three anaerobic digesters were evaluated. As part of a broader project examining the overall fate and effects of hydrolytic enzymes in biological sludge stabilization, this paper compares the performances of aerobic and anaerobic reactors used in this study and reports significant improvements in enzymatic treatment of activated sludge.

Practical determination of the rheological behavior of pasty biosolids.

In this paper, we demonstrate that the rheological behavior of pasty sewage sludges, regardless of origin, treatment or composition, follows a Herschel-Bulkley model. The yield stress and solid volume fraction are found to be the only two distinctive rheological characteristics of these materials. By scaling the shear rate and the shear stress with two parameters depending only on the yield stress and the solid fraction, the flow curves of 48 pasty sludges all fall along a unique dimensionless master curve. This result may be used in practice to determine, from simple, independent measurements, the rheological behavior of any pasty sludge: the yield stress can be measured with the help of the 'slump test' and the solid concentration determined from the organic and mineral matter contents. The results obtained with this technique are in very good agreement with those obtained by direct rheometry.