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Aerobic Biological Oxidation
Published in Gaetano Joseph Celenza, Industrial Waste Treatment Process Engineering, 2019
Finally, sludge composition establishes the ease of disposal, with or without final stabilization. Generally, any sludge containing regulated toxic constituents, which could leach into a landfill underground water table, will be expensive to dispose. Sludge metal content represents a special disposal problem, restricting direct land disposal, and affecting sludge incineration because of limits imposed on metal air emissions and ash disposal. Sludge composition is affected by reactor conditions as well as the quantity of feed components not biologically oxidized, adsorbed, and retained by the biofloc. The Process Engineer must consider waste sludge quality as part of the design criteria.
Evaluation of foamed bitumen efficiency in warm asphalt mixtures recycling
Published in Cândida Vilarinho, Fernando Castro, Mário Russo, Wastes: Solutions, Treatments and Opportunities, 2015
Cândida Vilarinho, Fernando Castro, Mário Russo
In the last years, an increase in volume of municipal wastewater caused by acceleration of population growth and urbanization process was observed [Lin & Ma, 2012]. Due to large quantity of generated municipal sewage sludge [Xu et al. 2012], one of the most important target of the EU is to achieve sustainable development in sewage sludge (SS) management. In accordance to the Council Directive 98/15/EEC amending Directive 91/271/EEC concerning the urban wastewater treatment ‘sludge arising from wastewater treatment shall be re-used whenever appropriate’. Its aim is to promote pro-ecological management of sewage sludge. Therefore, it is expected that by developing and adopting appropriate treatment methods, a significant amount of materials and energy will be recovered from sludge [Kliopova & Makarskiené, 2015]. In the last years, the European Project SUSAN (Sustainable and Safe Re-use of Municipal Sewage Sludge for Nutrient Recovery) was aimed to develop a sustainable and safe strategy for nutrient recovery from sewage sludge using thermal treatment [Adam et. al., 2009b]. The large benefit of sewage sludge incineration is 80–90% decline of stored sludge amount and this solution should be more frequently applied in modernization and investment projects [Chen et al., 2013]. Product of sewage sludge combustion is sewage sludge ash (SSA), which could be used as a raw material in engineering applications, eg. as fertilizers. The aim of this paper is an overview of the possible application of SSA in the agricultural purposes. WASTEWATER SEWAGE SLUDGE AS FERTILIZERS
Life Cycle Assessment of Municipal Wastewater and Sewage Sludge Treatment
Published in Mu Naushad, Life Cycle Assessment of Wastewater Treatment, 2018
Maria Teresa Moreira, Arias Andrea, Gumersindo Feijoo
The trade-off between anaerobic digestion, aerobic stabilization, and incineration of sewage sludge indicated that for eutrophication- and toxicity-related categories (except for terrestrial ecotoxicity), facilities performing anaerobic digestion followed by sludge incineration show higher environmental impacts compared with plants treating the sludge by aerobic stabilization prior to agricultural sludge application (Niero et al., 2014).
Applying ultrasound plus electrokinetics to enhance sludge dewatering
Published in Drying Technology, 2022
Arup Ratan Dey, Andrei Nekrasevits, R. Scott Semken, Aki Mikkola, Tuomas Sihvonen
Sludge incineration is more efficient and more profitable when the sludge being burned is drier. It should be at least 50 TS%.[4] Test results here revealed that low frequency high-power US combined with EK effectively enhances sludge dewatering and makes it possible to achieve significantly higher TS% levels. According to a study by Mobaraki, the combination of US and EK have great potential to enhance sludge dewatering.[23] Starting with an initial total solids content of 20%, best test results were obtained by applying 2 bar of pressure, 55 W of 15 kHz US, and 30 V of EK (cathode above and anode below) across a 30 mm sludge sample. Studies by Pilli and Mahmoud also support the finding here that the EK voltage range (30–50 V) and US frequency range (15-20kHz) are most effective for sludge dewatering.[15,27] Positioning the cathode above the sludge sample resulted in a 10% improvement in dewatering efficiency. A total solids content of 54 TS% was achieved within 60 min.
Effects of co-pyrolysis of rice husk and sewage sludge on the bioavailability and environmental risks of Pb and Cd
Published in Environmental Technology, 2021
Yan-Qin Yang, Min-Hua Cui, Jian-Chao Guo, Jing-Jing Du, Zhi-Yong Zheng, He Liu
According to the statistics, more than 30 million tons of sewage sludge (moisture content of 80%) were produced in China each year [1]. Numerous technologies have been developed for sludge disposal, e.g. incineration, landfill, land application. Yet these methods may cause secondary pollution due to the inadequate treatment of heavy metals [2]. Landfill and direct agricultural applications may generate undesired heavy metal leaching to soil and groundwater [3]. On the other hand, sludge incineration has also a high potential risk to the environment due to the dioxin production [4]. Compared to these methods, pyrolysis is an alternative technology and can efficiently minimize the volume of sludge, kill the pathogens and transform organic substances to bio-energy (e.g. bio-oil and pyrolytic gas) and biochars [5]. Previous studies have reported that sludge derived biochar can be used in the following options: agronomic application [6], activated carbon [7] and catalyst [8].
Sludge: next paradigm for enzyme extraction and energy generation
Published in Preparative Biochemistry and Biotechnology, 2019
Santosh Kumar Karn, Awanish Kumar
Sludge is aimed for complete oxidation at high temperature, which is known as incineration. The energy produced in the incineration process can be used for the production of electricity. Nowadays, sludge incineration processes are increasingly focused on the recovery of energy from the sludge as electricity. Incineration of sludge is currently applied worldwide more and more for the electricity generation. Sludge incineration processes are also doing the recovery of heat in the form of steam and steam produces power through turbines, which works to produce power through the electric generator. However, this process also causes pollution in another form. Because of the composition of the inorganic compounds in the sludge and the high temperatures applied in the incineration, the heavy metals are very resistant and well-immobilized to leaching. This ash can be used as a source for the production of bricks, cement, or has to be disposed of. Since the incineration process deals with large quantities of polluted exhaust gases, there should be an efficient and adequate gas treatment system, but the costs of the systems are very high. This is the main reason that sludge incineration is highly expensive. Currently, the processes of sludge incineration are increasing and focused on the recovery of energy in the form of heat (steam), but the energy produced in the incineration process can also be used for the production of electricity. The amount of energy obtained from sludge strongly depends upon the water content of the sludge, modification, and performance of the incineration, drying processes, and mechanical dewatering. Incineration of sludge is applied worldwide currently, more and more in combination with energy recovery. In coal-fired power plants, co-incineration of sewage sludge is applied in practice. Incineration of sludge is widely used on a large scale basis in many urban areas of Japan and Europe, which are highly populated. The process should be applied on a large scale.