Application Of Granular Sludge Research Articles

Thermal characterization of granular sludges from biologic treatments and its application to the generation of biogas

The application of granular sludge from biological treatment plants can become an economically and environmentally viable process as a renewable source of energy. It is available in most countries, and its application can diversify the local energy potential. However, in order to achieve such benefits and make possible the development of more efficient conversion processes, prior knowledge of the composition of these materials is essential. In this sense, samples of granular sludge were obtained from upflow anaerobic sludge blanket reactors for the treatment of: (1) poultry slaughterhouse waste (Tiete—SP); (2) poultry slaughterhouse waste (Pereiras—SP); (3) wastewater treatment plant (Sao Carlos—SP) and (4) a mix of sludges 1, 2 and 3. Biogas generation tests in anaerobic batch reactors fed with sodium acetate and glucose separately as carbon sources were performed with samples 1, 2, 3 and 4, at initial pH 7.0 and 30 °C. Characteristic decomposition profiles were observed in the granular sludge tested. The two poultry slaughterhouse waste (samples 1 and 2) presented higher proportions of organic substrate molecules for the methanogenesis than the sanitary sewage sludge (sample 3), thus facilitating the production of the highest biogas, as verified in the tests carried out. The thermal characterization of the samples was relevant to the methane generation tests demonstrating the potential for the generation of this fuel.

Activated Sludge and other Aerobic Suspended Culture Processes.

In this paper, removal model of activated sludge, cultivation and application of granular sludge, the population dynamics, removal and influence of toxic pollutants, and design and control of the sewage treatment system are reviewed in 2017. Several studies suggest that the cultivation of granular sludge is mainly affected by aeration rate, hydraulic velocity and culture environment. Toxic pollutants can be partially degraded by microorganisms, which lead to the change of microbial community structure. The co-digestion of activated sludge and other solid wastes can produce biomass energy, which is a more promising and solid waste treatment method.

Gas-enhanced operation and stepwise organic stressing as a new alternative in realising successful sludge granulation in high-rate anaerobic bioreactor for wastewater treatment

ABSTRACTAnaerobic biotechnology is becoming the method of choice for many types of wastewater treatment. Application of granular sludge in the upflow anaerobic sludge bed (UASB) is important in maximising the overall treatment capacity benefiting from its fast settling ability and excellent biological activities. This study explores a new alternative for achieving sludge granulation in a sulfidogenic UASB reactor. Granules were first observed at day 30 and achieved the average diameters of 820 µm at day 162. The scanning electron microscope analysis showed that the granules have a regular spherical-shaped outline boundary, and a rough outer surface layer with a channel-like porous structure. The confocal laser scanning microscopy analysis illustrated that the extracellular polymeric substances (EPS) were more evenly distributed across the granules under a gas-enhanced operation than at the control stage. For the control stage operation without gas-enhanced operation, no granule disintegration was observed...

Comparison methane production potential between granular and suspended sludge at varying ammonia concentration

Anaerobic digestion of Thermally Hydrolyzed Wasted Sludge (THWS) with high strength ammonia was evaluated through batch and two-phase Upflow Anaerobic Sludge Blanket (UASB) reactors with two kinds of anaerobic microbial types (suspended and granular). In the batch test, biogas yield and gas production rate increased as microbial concentration increased for the wastewaters with a high ammonia concentration of 0.8 g FA/L. Also, the lag time and finishing time of gas production could be shortened by applying higher microbial concentrations. The granular sludge presented a higher biogas yield, shorter lag time and shorter finishing time of gas production when compared with suspended sludge. The comparative reactor operation using suspended sludge and granular sludge demonstrated that the granular sludge had more competitive advantages for the biogas production from THWS at a high ammonia concentration of 9.2 g NH4+/L. Therefore, the application of granular sludge could be more appropriate for the anaerobic treatment of wastewater containing high strength ammonia since the granular sludge can have a higher resistance to toxicity and maintain a higher microbial concentration.

The potential of anaerobic bacteria to degrade chlorinated compounds

Chlorinated ethenes and chlorinated aromatics are often found as pollutants in sediments, groundwater, and wastewater. These compounds were long considered to be recalcitrant under anaerobic conditions. In the past years however, dechlorination of these compounds has been found to occur under anaerobic conditions at contaminated sites and in wastewater treatment systems. This dechlorination is mainly attributed to halo-respiring bacteria, which are able to couple this dechlorination to energy conservation via electron transport coupled phosphorylation. The dechlorinating activities of the halo-respiring bacteria seem to be confined to the dechlorination of chloroethenes and chlorinated aromatic compounds. In addition, methanogenic and acetogenic bacteria are also able to reduce the chlorinated ethenes via a-specific cometabolic pathways. Although these latter reactions may not be important in the remediation of contaminated sites, they may be of substantial influence in the start-up of remediation processes and in the application of granular sludge from UASB reactors. Specific halo-respiring bacteria may be used to increase the dechlorination activities via bioaugmentation in the case that the appropriate microorganisms are not present at the contaminated site or in the sludge.