Search results for "PAPER"
showing 10 items of 2166 documents
The role of EPS in the foaming and fouling for a MBR operated in intermittent aeration conditions
2016
Abstract This work investigates the causes of foaming and fouling in an Intermittent Aerated – Membrane BioReactor (IA-MBR) used for wastewater treatment. The experiment was divided into three periods with different aerated regimes expressed with different t aeration /t cycle ratio (Period I: 60 min/180 min, Period II: 80 min/180 min, Period III: 30 min/90 min). The advanced foaming tests used allow the study of the role of extracellular polymeric substances (EPSs) on foaming and fouling. In general, in the Periods I and II, good correlations between the EPSs and the Modified Scum Index without purification (MSI 0 ) and the Foam Power were observed. The results shown that the filamentous mi…
Precipitation assessment in wastewater treatment plants operated for biological nutrient removal: a case study in Murcia, Spain.
2009
The Murcia Este Wastewater Treatment Plant is the largest wastewater treatment plant in Murcia (Spain). The plant operators have continuously found pipe blockage and accumulation of solids on equipment surfaces during the anaerobic digestion and post-digestion processes. This work studies the precipitation problems in the Murcia Este Wastewater Treatment Plant in order to locate the sources of precipitation and its causes from an exhaustive mass balance analysis. The DAF thickener and anaerobic digester mass balances suggest that most of the polyphosphate is released during excess sludge thickening. Despite the high concentrations achieved in the thickened sludge, precipitation does not occ…
Two-stage anaerobic digestion of tomato, cucumber, common reed and grass silage in leach-bed reactors and upflow anaerobic sludge blanket reactors
2010
Abstract Anaerobic digestion of tomato, cucumber, common reed and grass silage was studied in four separate two-stage reactor configuration consisting of leach bed reactor (LBR) and upflow anaerobic sludge blanket reactor (UASB). LBR studies showed that COD solubilization for cucumber and grass silage was higher (50%) than tomato (35%) and common reed (15%). Results also showed that 31–39% of initial TKN present in tomato and cucumber was solubilized in the leachates and 47–54% of the solubilized TKN was converted to NH4-N. The corresponding values for common reed and grass silage were 38–50% and 18–36%, respectively. Biomethanation of the leachates in UASB reactors resulted in methane yiel…
Multivariate Correlation between Analytical Data for Various Organics Dissolved during Autohydrolysis of Silver Birch (Betula pendula) Chips and Trea…
2014
Autohydrolysis pre-treatments were performed for the production of hemicellulose-rich autohydrolysates from silver birch (Betula pendula) chips prior to chemical pulping. Pre-treatment conditions were varied with respect to time (from 30 to 120 min) and temperature (130 and 150 °C), covering a P-factor range from 10 to 238. Hydrolysates were analyzed in terms of carbohydrates, lignin, volatile organic acids, and furanoic compounds. The analytical data were subjected to various chemometric techniques to establish the relationships between dissolved organic components, hardwood and softwood used in the experiments, and applied pre-treatment conditions. Using this method, differences between t…
Sewage sludge management for phosphorus recovery as struvite in EBPR wastewater treatment plants
2008
The influence of separate and mixed thickening of primary and secondary sludge on struvite recovery was studied. Phosphorus precipitation in the digester was reduced from 13.7 g of phosphorus per kg of treated sludge in the separate thickening experiment to 5.9 in the mixed thickening experiment. This lessening of the uncontrolled precipitation means a reduction of the operational problems and enhances the phosphorus availability for its later crystallization. High phosphorus precipitation and recovery efficiencies were achieved in both crystallization experiments. However, mixed thickening configuration showed a lower percentage of phosphorus precipitated as struvite due to the presence of…
Anaerobic on-site treatment of black water and dairy parlour wastewater in UASB-septic tanks at low temperatures.
2004
Anaerobic on-site treatment of synthetic black water (BW) and dairy parlour wastewater (DPWW) was studied in two-phased upflow anaerobic sludge blanket (UASB)-septic tanks at low temperatures (10-20 degrees C). At all temperatures, total chemical oxygen demand (COD(t)) removal was above 90% with BW and above 80% with DPWW and removal of total suspended solids (TSS) above 90% with both wastewaters. Moreover, dissolved COD (COD(dis)) removal was approx. 70% with both wastewaters indicating good biological activity of the sludges. With BW, a single-phased reactor was found sufficient for good COD removals, while with DPWW, a two-phased process was required. Temperature optimum of reactor sludg…
Chlorinated cymenes in effluents of two Finnish pulp mills in 1990–1993
1995
Abstract Seven chlorocymenes (CYMS) and 2,3,6-trichloro-p-cymenene (236CYMD) were determined in effluents of biological purification plants of two Finnish pulp mills during the years 1990–1993. Both pulp mills changed their bleaching process and consequently, a steep decreasing trend in emitted amounts of the studied compounds was noticed.
Producing high-strength liquor from mesophilic batch acidification of chicken manure.
2015
This report describes the results from anaerobic batch acidification of chicken manure as a mono-substrate studied under mesophilic conditions. The manure was diluted with tap water to prevent methane formation during acidification and to improve mixing conditions by reducing fluid viscosity; no anaerobic digester sludge has been added as an inoculum. Highest acidification rates were measured at concentrations of 10 gVS L−1 and 20 gVS L−1; the pH value remained high (pH 6.9–7.9) throughout the test duration and unexpected fast methane formation was observed in every single batch. At substrate concentrations of 10 gVS L−1 there was a remarkable methane formation representing a value of 82% …
The closure of water circuits by internal thermophilic (55 and 70�C) anaerobic treatment in the thermomechanical pulping process
1997
The suitability of an internal thermophilic anaerobic treatment system for closing the water circuits in thermomechanical pulp (TMP) production was studied. The dissolution of wood organics in the water circuit was simulated by hot disintegration of TMP pulp, while the water system closure was simulated by repeated hot disintegration of TMP pulp with recirculated water. The upflow anaerobic sludge blanket (UASB) reactors were started at 55 and 70°C with mesophilic inoculum, and stable performances were established within 60 days at both temperatures. Closing the water circuits without internal treatment rapidly resulted in increased chemical oxygen demand (COD) in the recirculated water. In…
Pilot-scale comparison of thermophilic aerobic suspended carrier biofilm process and activated sludge process in pulp and paper mill effluent treatme…
2004
Thermophilic aerobic treatment of settled pulp and paper mill effluent was studied under mill premises with two comparative pilot processes; suspended carrier biofilm process (SCBP) and activated sludge process (ASP). Full-scale mesophilic activated sludge process was a reference treatment. During the runs (61 days) hydraulic retention times (HRTs) were kept 13 ± 5 h and 16 ± 6 h for SCBP and ASP, respectively. Corresponding volumetric loadings rates (VLR) were 2.7 ± 0.9 and 2.2 ± 1.0 kg CODfilt m-3d-1. Temperatures varied between 46 to 60°C in both processes. Mesophilic ASP was operated with HRT of 36 h, corresponding VLR of 0.7 kg CODfilt m-3d-1. Both SCBP and ASP achieved CODfilt (GF/A f…