Search results for "Aeration"
showing 10 items of 73 documents
Influence of aeration on the localized trenching on aluminium alloys
2010
This paper aims to make the difference between alcalinisation and micro-galvanic corrosion in the mechanism of the corrosion of Al alloys. Using a pH microprobe, the pH changes inside a pure water droplet deposited on a thermal aged 2011 aluminium alloy were scanned. These pH variations, depending on the position inside the droplet, were related to the heterogeneous corrosion attacks of the aluminium surface quantified by AFM measurements. A modelling investigation is proposed to evaluate the distinct roles of alcalinisation, due to the oxygen reduction reaction (ORR), and the galvanic coupling between intermetallic particles and the surrounding matrix. It can be concluded that the former c…
Potential use of the organic fraction of municipal solid waste in anaerobic co-digestion with wastewater in submerged anaerobic membrane technology
2016
Food waste was characterized for its potential use as substrate for anaerobic co-digestion in a submerged anaerobic membrane bioreactor pilot plant that treats urban wastewater (WW). 90% of the particles had sizes under 0.5 mm after grinding the food waste in a commercial food waste disposer. COD, nitrogen and phosphorus concentrations were 100, 2 and 20 times higher in food waste than their average concentrations in WW, but the relative flow contribution of both streams made COD the only pollutant that increased significantly when both substrates were mixed. As sulphate concentration in food waste was in the same range as WW, co-digestion of both substrates would increase the COD/SO4-S rat…
Economic analysis of the scale-up and implantation of a hollow fibre membrane contactor plant for nitrogen recovery in a full-scale wastewater treatm…
2021
[EN] Nitrogen recovery technologies such as the hollow fibre membrane contactor are now being developed. However, an economic analysis is needed prior to their full-scale application in wastewater treatment plants. The aim of this study was to analyse the economic and environmental aspects of scaling-up this method. To achieve it, a full-scale 40,000 m3·day¿1-wastewater treatment plant influent flow rate was simulated jointly with a membrane contactor plant to evaluate the minimum costs of optimum operating conditions of membrane contactors (pH, feed flow rate and membrane surface). The optimum conditions for treating 600 m3·day¿1 of reject water was found to be 10 pH, 0.08 m3·s¿1 feed flow…
Heat shock protein Hsp70 expression and DNA damage in Baikalian sponges exposed to model pollutants and wastewater from Baikalsk Pulp and Paper Plant
2002
Abstract Lake Baikal, a unique habitat for a great number of endemic species, is the largest freshwater reservoir in the world which is still largely unaffected by anthropogenic pollution, except for some shore regions with industrial activity. The expressions of a biomarker of exposure (heat shock protein Hsp70) and a biomarker of effect (DNA single-strand breaks) were measured for the first time in endemic Baikalian sponge species (Baikalospongia intermedia, Lubomirskia fusifera, and Lubomirskia abietina). Tissue cubes of B. intermedia and dissociated cells of L. fusifera and L. abietina reacted to temperature stress (10–16 °C above ambient temperature) with a time-dependent increase in e…
Methane and leachate pollutant emission potential from various fractions of municipal solid waste (MSW): effects of source separation and aerobic tre…
2002
The effects of source-separation of putrescibles as well as aerobic pre-treatment and landfill aeration on the pollutant emission potential of methane and leachate pollutants were studied in the fresh (PFMSW) and composted (CPFMSW) source-separated putrescible fraction of municipal solid waste, and in the grey waste, and in lysimeter landfilled grey waste and ten-year-old unsorted MSW from our landfill lysimeter study. After 0, 23 and 51 days, an aerobic lysimeter experiment, an elution test and biochemical methane potential (BMP) test was done on samples. PFMSW had high methane (CH4) potential (410 m3CH4 t-1TS) as well as a high amount of ammonium-nitrogen (3.6 kg NH4-N) was eluted, where…
Energy intensity modeling for wastewater treatment technologies.
2018
Wastewater treatment plants (WWTPs) are energy intensive facilities; therefore increased pressure has been placed on managers and policy makers to reduce the facilities' energy use. Several studies were conducted to compare the energy intensity (EI) of WWTPs, which showed large dispersion in EI among the facilities. In the present study, the degree EI influenced WWTPs was tested using a set of technical variables by modeling the EI of a 305 WWTP sample grouped into five secondary treatment technologies. Results indicated the following two major findings: i) WWTPs using conventional activated sludge, extended aeration, trickling biofilters, and biodisks exhibited significant economies of sca…
Loop seals in circulating fluidized beds – Review and parametric studies using CPFD simulation
2020
Abstract Loop seal is a robust particle recycling technique used in circulating fluidized bed (CFB) reactors. The rate and the location of the loop seal aeration exert a significant impact on the rate of particle circulation (GS). The standpipe balances the cumulative pressure drop across the rest of the CFB by adjusting its particle height or gas-particle slip velocity. Higher fraction of the loop seal aeration naturally flows down to riser. Increased pressure drop in the standpipe results in high rate of particle circulation. Computational-particle-fluid-dynamic (CPFD) code is customized for multiphase flow modelling. The inbuilt tool of “BC connectors” was incorporated to downsize a CFB …
Expert control of DO in the aerobic reactor of an activated sludge process
2000
Abstract An expert control structure is proposed for the control of dissolved oxygen (DO) in a Nitrification Denitrification Biological Excess Phosphorus Removal (NDBEPR) plant to account for the several processes that are influenced by the DO concentration in the aerator. In the scheme a supervisory fuzzy controller determines the set point of an inner DO control loop where an Adaptive Robust Generic Model Control (ARGMC) controller is used. The fuzzy supervisory control has a hierarchical structure. Off-line measurements of biological parameters of influent and effluent streams can be used to periodically update the set points of the fuzzy controllers. The complete control scheme has been…
Particle Suspension in Vortexing Unbaffled Stirred Tanks
2016
Three-phase processes in which particle suspension has to be achieved in conjunction with gas dispersion are traditionally carried out in sparged, baffled stirred tanks. The operation of such tanks can suffer, however, from particles tending to block the sparger holes. A viable alternative might be provided by uncovered unbaffled stirred tanks (UUSTs), where gas self-injection can occur when the free-surface vortex reaches the impeller blades and gas bubbles begin to be ingested by the liquid. In this work, the particle suspension and liquid aeration performances in three-phase UUSTs were experimentally investigated and compared with relevant literature correlations concerning baffled syste…
Effect of micro-aeration and leachate replacement on COD solubilization and VFA production during mono-digestion of grass-silage in one-stage leach-b…
2010
The effect of micro-aeration and leachate replacement with fresh water on chemical oxygen demand (COD) solubilization and volatile fatty acid (VFA) production during the mono-digestion of grass-silage in one-stage leach-bed reactors (LBRs) was investigated in four LBRs, L0 (control), L1, L2 and L3 in batch mode at 35 + or - 1 degrees Celsius for 57 days. Results showed that leachate replacement without pH adjustment (L3) resulted in 2.7 and 1.3 times more SCOD in the leachate compared to control (L0) or leachate replacement with initial pH adjustment (L1), respectively. Micro-aeration at flow rate of 1 L min(-1) (2.5 L of air) in L2 resulted in 4-fold increase in VFA production (from 2.2 to…