Search results for "WASTE"
showing 10 items of 2580 documents
Calibration of denitrifying activity of polyphosphate accumulating organisms in an extended ASM2d model
2010
Abstract This paper presents the results of an experimental study for the modelling and calibration of denitrifying activity of polyphosphate accumulating organisms (PAOs) in full-scale WWTPs that incorporate simultaneous nitrogen and phosphorus removal. The convenience of using different yields under aerobic and anoxic conditions for modelling biological phosphorus removal processes with the ASM2d has been demonstrated. Thus, parameter ηPAO in the model is given a physical meaning and represents the fraction of PAOs that are able to follow the DPAO metabolism. Using stoichiometric relationships, which are based on assumed biochemical pathways, the anoxic yields considered in the extended A…
The influence of solid retention time on IFAS-MBR systems: Assessment of nitrous oxide emission
2017
The aim of the present study was to investigate the nitrous oxide (N2O) emissions from a moving bed based Integrated Fixed Film Activated Sludge (IFAS) - membrane bioreactor (MBR) pilot plant, designed according to the University of Cape Town (UCT) layout. The experimental campaign had a duration of 110 days and was characterized by three different sludge retention time (SRT) values (â, 30 d and 15 d). Results highlighted that N2O concentrations decreased when the biofilm concentrations increased within the aerobic reactor. Results have shown an increase of N2O with the decrease of SRT. Specifically, an increase of N2O-N emission factor occurred with the decrease of the SRT (0.13%, 0.21% …
Effects of solid–liquid separation on recovering residual methane and nitrogen from digested dairy cow manure
2006
The feasibility of optimizing methane and nitrogen recovery of samples obtained from farm biogas digester (35 degrees C) and post-storage tank (where digested material is stored for 9-12 months) was studied by separating the materials into different fractions using 2, 1, 0.5 and 0.25 mm sieves. Mass-balances revealed that digested material mainly consists of0.25 mm (60-69%) and2 mm (18-27%) fractions, while fractions between 2 and 0.2 mm made the rest. Incubation of solid fractions0.25 mm of digester material at 35 degrees C resulted in specific methane yields of 0.060-0.085 m(3)kg(-1) volatile solids (VS) during initial 30-50 d and 0.16-0.18 m(3)kg(-1)VS at the end of 340 d incubation. Sim…
Simultaneous nitrogen and organic carbon removal in aerobic granular sludge reactors operated with high dissolved oxygen concentration
2013
Simultaneous nitrification and denitrification (SND) together with organic removal in granules is usually carried out without Dissolved Oxygen (DO) concentration control, at ‘‘low DO’’ (with a DO 7–8 mg/L, during feast and famine conditions respectively). In particular, different strategies of cultivation and several organic and nitrogen loading rate have been applied, in order to eval- uate the efficiencies in SND process without dissolved oxygen control. The results show that, even under conditions of high DO concentration, nitrogen and organic matter can be simultaneously removed, with efficiency >90%. Nevertheless, the biological conditions in the inner layer of the granule may change sig- …
Anaerobic on-site treatment of kitchen waste in combination with black water in UASB-septic tanks at low temperatures.
2006
Anaerobic on-site treatment of a mixture of black water and kitchen waste (BWKW) was studied using two-phased upflow anaerobic sludge blanket (UASB) septic tanks at the low temperatures of 20 and 10 degrees C. Black water (BW) was also treated alone as reference. The two-phased UASB-septic tanks removed over 95% of total suspended solids (TSS) and 90% of total chemical oxygen demand (COD(t)) from both BWKW (effluent COD(t) 171-199mg/l) and BW (effluent COD(t) 92-100mg/l). Also, little dissolved COD (COD(dis)) was left in the final effluents (BW 48-70mg/l; BWKW 110-113mg/l). Part of total nitrogen (N(tot)) was removed (BW 18% and BWKW 40%) and especially at 20 degrees C ammonification was ef…
Elevated nutrient concentrations in headwaters affected by drained peatland
2018
Abstract Nutrient export from drained peatland has significant impacts on aquatic environments in Nordic catchments. Spatial information on variations in nutrient concentrations across different landscapes and land uses is needed to design measures for achieving the good ecological status of the EU Water Framework Directive. In this study we determined background concentrations in natural peatland-dominated streams and examined effects of peatland use practices on water quality in headwater catchments. We quantified sources for different elements by joint analysis of water chemistry, isotopes, and hydrology for 62 small catchments in North Ostrobothnia, Finland. Concentrations of nutrients …
Electrocoagulation treatment of peat bog drainage water containing humic substances
2015
Abstract Electrocoagulation (EC) treatment of 100 mg/L synthetic wastewater (SWW) containing humic acids was optimized (achieving 90% CODMn and 80% DOC removal efficiencies), after which real peat bog drainage waters (PBDWs) from three northern Finnish peat bogs were also treated. High pollutant removal efficiencies were achieved: Ptot, TS, and color could be removed completely, while Ntot, CODMn, and DOC/TOC removal efficiencies were in the range of 33–41%, 75–90%, and 62–75%, respectively. Al and Fe performed similarly as the anode material. Large scale experiments (1 m3) using cold (T = 10–11 °C) PBDWs were also conducted successfully, with optimal treatment times of 60–120 min (applying…
Chlorinated dioxins and dibenzothiophenes in fly ash samples from combustion of peat, wood chips, refuse derived fuels and liquid packaging boards
1995
Abstract Peat, wood chips, refuse derived fuel and liquid packaging board in different combinations were burned at a temperature of at least 850 °C. Fly ash samples from these combustions were analyzed for polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzothiophenes (PCDBTs) by high resolution GC/MS. The concentrations of tri- and tetrachlorodibenzothiophenes and tri-, tetra- and pentachlorodioxins were highest when mixtures of wood chips and refuse derived fuel (RDF) were burned. The fly ash from the combustion of pure peat pellets did not contain any polychlorinated dibenzothiophenes. When wood chips and RDF were burned the concentrations of chlorinated compounds in fly…
Screening of novel plants for biogas production in northern conditions.
2013
Abstract The objective of this study was to screen nine annual or perennial novel plants for biogas production cultivated in years 2007–2010 in Finland. The most promising novel plants for biogas production were found to be brown knapweed, giant goldenrod and Japanese millet producing 14–27 t total solids/ha and 4000–6100 Nm 3 CH 4 /ha. The specific methane yields of all studied plants varied from 170 to 381 Nm 3 CH 4 /t volatile solids (VS), depending on harvest time and plant species. Co-digestion of brown knapweed with cow manure in continuously stirred tank reactor was investigated and the highest methane yield was 254 NL CH 4 /kg VS, when the share of brown knapweed was 50% in the fe…
Photocatalytic activity of TiO2/SiO2 systems
2009
Silica-supported TiO(2) powders were synthesized by a wet method under mild conditions. The aim of the work was the preparation of TiO(2)/SiO(2) additives for photocatalytic cements. Three types of commercial SiO(2) were used as supports: Cabot, Axim and Fly Ash. Cabot silica was ultra-pure whereas the other two silica contained different percentages of various oxides. The TiO(2)/SiO(2) samples, denoted TiO(2)/Cabot, TiO(2)/Axim and TiO(2)/Fly Ash, were prepared by boiling suspensions obtained by addition of silica to a solution of TiCl(4) in water (volume ratio 1:10). The photocatalytic activity was evaluated in a gas-solid system both in batch and in continuous reactors using 2-propanol a…