1,720,974 research outputs found
Small Communities Decentralized Wastewater Treatment: Assessment of Technological Sustainability
No full textBioelectrochemical systems for sustainable groundwater denitrification and removal of arsenic and chromium
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Biological combination processes for efficient removal of pharmaceutically active compounds from wastewater: A review and future perspectives
No full textEnergy Recovery from Wastewater: A Study on Heating and Cooling of a Multipurpose Building with Sewage-Reclaimed Heat Energy
No full textTo achieve technically-feasible and socially-desirable sustainable management of urban areas, new paradigms have been developed to enhance the sustainability of water and its resources in modern cities. Wastewater is no longer seen as a wasted resource, but rather, as a mining ground from which to obtain valuable chemicals and energy; for example, heat energy, which is often neglected, can be recovered from wastewater for different purposes. In this work, we analyze the design and application of energy recovery from wastewater for heating and cooling a building in Brno (Czech Republic) by means of heat exchangers and pumps. The temperature and the flow rate of the wastewater flowing in a sewer located in the proximity of the building were monitored for a one-year period, and the energy requirement for the building was calculated as 957 MWh per year. Two options were evaluated: heating and cooling using a conventional system (connected to the local grid), and heat recovery from wastewater using heat exchangers and coupled heat pumps. The analysis of the scenarios suggested that the solution based on heat recovery from wastewater was more feasible, showing a 59% decrease in energy consumption compared to the conventional solution (respectively, 259,151 kWh and 620,475 kWh per year). The impact of heat recovery from wastewater on the kinetics of the wastewater resource recovery facility was evaluated, showing a negligible impact in both summer (increase of 0.045 °C) and winter conditions (decrease of 0.056 °C)
Agro-food industry wastewater treatment with microbial fuel cells: energetic recovery issues
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Sustainability of decentralized wastewater treatment technologies
No full textIn many Countries, small communities are required to treat wastewater discharges to increasing standards of lesser environmental impacts, but must achieve that goal at locally sustainable costs. While biological membrane treatment (membrane bio-reactors (MBRs)) is quickly becoming the industry standard for centralized wastewater treatment plants, and would also be ideally suited also for small plants potentially subject to relatively large hydraulic load variations, its investment and operating costs are usually high for that class of applications. Consequently, small treatment plants are generally configured as anoxic or aerated biological tanks with little sedimentation, making them quite susceptible to hydraulic loads transient and sludge quality changes. As an alternative, Constructed Wetlands Systems (CWSs) are gradually and successfully being introduced in many Countries. CWSs are designed to utilise the natural functions of wetland vegetation, soils and their microbiological populations to treat wastewater. Pretreatment occurs by filtration and settling, followed by bacterial decomposition in a natural-looking lined marsh. A new technology, a new type of membrane-like aerobic reactor initially designed for the degradation of hydrocarbon-derived groundwater contaminants, was recently tested for treating domestic, with performance similar to that of MBRs. Examples from the above applications are illustrated and compared in this paper. The paper also discusses merits and drawbacks of the various illustrated technologies, in view of their sustainability potential, and according to the new development paradigms for urban water systems, that encourage the development of local water-cycle clusters with local reuse and recycle of the resource, and possible local recovery of energy and/or materials.</jats:p
Side-Stream Phosphorus Recovery in Activated Sludge Processes
No full textPrecipitation of mineral phosphates from wastewater treatment processes is an excellent method for phosphorus recovery, leading to the formation of compounds with high fertilizing value. Conventionally, P-precipitation processes are mostly applied to supernatant of anaerobic sludge digestates, due to their high P and N residual contents. This study concerns P-recovery in a pilot-scale side-stream reactor from aerobic (activated sludge) wastewater liquor. The effect of process retention time and pH was determined using sodium hydroxide and calcium hydroxide as alternative pH buffer reagents, in both synthetic and real wastewater. Equilibrium mass balance calculations were first applied to estimate the theoretical final composition of P-precipitates under different process conditions; then, actual precipitation experiments were carried out with synthetic wastewater to define optimal process operating parameters in controlled conditions. Results showed that phosphorus precipitation was affected mainly by solution pH and did not significantly depend on the reactor’s retention time. These findings were validated by operating the process with real wastewater: on average, 61.2% and 90.4% phosphorus precipitation (recovery) were achieved at pH = 8.5 and 9.0 under a controlled Mg:NH4:P molar ratio of 5:5:1, using sodium hydroxide as acidity buffer. The main fraction of final precipitates consisted of calcium phosphate compounds, while struvite, bobierrite and calcite showed up in smaller proportions. It was also shown that dosage of calcium hydroxide for pH adjustment, without any other chemicals for molar ratios adjustment of the solution, has great potential for P recovery in the form of a calcium phosphate-rich precipitate, usable for fertilizer, with 75.6% phosphorus removal in mineral form at pH = 8.5. The process is much less costly to operate than struvite precipitation, and more energetically sustainable. This scheme could be ideally suited for application in facilities operating under an enhanced phosphorus removal process scheme
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