Search results for " EXERCISE"
showing 10 items of 1621 documents
Monitoring pH and electric conductivity in an EBPR sequencing batch reactor
2004
This paper presents laboratory-scale experimentation carried out to study enhanced biological phosphorus removal. Two anaerobic aerobic (A/O) sequencing batch reactors (SBR) have been operated during more than one year to investigate the information provided by monitoring pH and electric conductivity under stationary and transient conditions. Continuous measurements of these parameters allow detecting the end of anaerobic phosphorus release, of aerobic phosphorus uptake and of initial denitrification, as well as incomplete acetic acid uptake. These results suggest the possibility of using pH and electric conductivity as control parameters to determine the length of both anaerobic and aerobi…
Anaerobic on-site black water and kitchen waste treatment using UASB-septic tanks at low temperatures.
2006
Anaerobic on-site treatment of black water (BW) and a mixture of black water and kitchen waste (BWKW) was studied in a two-phased upflow anaerobic sludge blanket septic tank (UASBst) at 10–20 °C. The processes were fed either continuously or discontinuously (twice per weekday). Moreover, BWKW was post-treated for nitrogen removal in an intermittently aerated moving bed biofilm reactor (MBBR) at 20 °C. Removal of total chemical oxygen demand (CODt) was efficient at minimum 90% with all three UASBst at all temperatures. Removal of dissolved COD (CODdis) was also high at approx. 70% with continuously fed BW and discontinuously fed BWKW, while with discontinuous BW feeding it was 20%. Temperatu…
Effect of additives on process stability of mesophilic anaerobic monodigestion of pig slaughterhouse waste
2012
The effect of two additives on anaerobic monodigestion of pig slaughterhouse waste was studied in three laboratory scale continuously stirred tank reactors (CSTRs) operated for 242-284 days at 35°C. A higher organic loading rate (OLR), namely 2.25 kg volatile solids (VS)/m(3)d with a hydraulic retention time (HRT) of 30 d was feasible with an additive containing Fe, HCl and trace elements while an OLR of 1.5 kg VS/m(3)d (HRT 30 d) led to instabilities in CSTR with an additive consisting of Fe and HCl and in CSTR without additives. Methane yields of ca. 700 dm(3) CH(4)/kg VS(fed) were obtained in all reactors under stable conditions. Both additives decreased H(2)S concentration of the biogas…
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…
Methane recovery efficiency in a submerged anaerobic membrane bioreactor (SAnMBR) treating sulphate-rich urban wastewater: Evaluation of methane loss…
2012
The present paper presents a submerged anaerobic membrane bioreactor (SAnMBR) as a sustainable approach for urban wastewater treatment at 33 and 20 C, since greenhouse gas emissions are reduced and energy recovery is enhanced. Compared to other anaerobic systems, such as UASB reactors, the membrane technology allows the use of biogas-assisted mixing which enhances the methane stripping from the liquid phase bulk. The methane saturation index obtained for the whole period (1.00 ± 0.04) evidenced that the equilibrium condition was reached and the methane loss with the effluent was reduced. The methane recovery efficiency obtained at 20 C (53.6%) was slightly lower than at 33 C (57.4%) due to …
Trace metals supplementation in anaerobic membrane bioreactors treating highly saline phenolic wastewater
2017
Biomass requires trace metals (TM) for maintaining its growth and activity. This study aimed to determine the effect of TM supplementation and partitioning on the specific methanogenic activity (SMA), with a focus on cobalt and tungsten, during the start-up of two lab-scale Anaerobic Membrane Bioreactors (AnMBRs) treating saline phenolic wastewater. The TM partitioning revealed a strong accumulation of sodium in the biomass matrix and a wash-out of the majority of TM in the reactors, which led to an SMA decrease and a low COD removal of about 30%. The SMA exhibits a maximum at about 6 g Na+ L−1 and nearly complete inhibition at 34 g Na+ L−1. The dose of 0.5 mg L−1 of tungsten increases the …
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…
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…
Relating ions concentration variations to conductivity variations in a sequencing batch reactor operated for enhanced biological phosphorus removal
2006
In this paper a deterministic relationship between ionic conductivity and phosphorus concentration variations in an enhanced biological phosphorus removal (EBPR) process is established. Conductivity shows a strong correlation with phosphorus in both anaerobic and aerobic stages, increasing or decreasing when phosphorus is released or taken up, respectively. Since the end of these processes can be detected by examining the conductivity profile in a cycle, useful information on the EBPR performance and stability is available. This information can be used for adjusting the length of the anaerobic and aerobic stages. Therefore, online process control based on inexpensive and easy to maintain se…