Treatment of winery wastewaters in a membrane submerged bioreactor.

Wine production is seasonal, and thus the wastewater flow and its chemical oxygen demand (COD) concentrations greatly vary during the vintage and non-vintage periods, as well as being dependant on the winemaking technologies used, e.g. red, white or special wines production. Due to this seasonal high variability in terms of organic matter load, the use of membrane biological reactors (MBR) could be suitable for the treatment of such wastewaters. MBR offers several benefits, such as rapid start up, good effluent quality, low footprint area, absence of voluminous secondary settler and its operation is not affected by the settling properties of the sludge. A pilot scale hollow fibre MBR system of 220 L was fed by adequately diluting white wine with tap water, simulating wastewaters generated in wineries. The COD in the influent ranged between 1,000 and 4,000 mg/L. In less than 10 days after the start up, the system showed a good COD removal efficiency. The COD elimination percentage was always higher than 97% regardless of the organic loading rate (OLR) applied (0.5-2.2 kg COD/m3 d), with COD concentrations in the effluent ranging between 20 and 100 mg/L. Although the biomass concentration in the reactor increased from 0.5 to 8.6 g VSS/L, the suspended solids concentration in the effluent was negligible. Apparent biomass yield was estimated in 0.14 g VSS/g COD.     

Simultaneous removal of ammonium-nitrogen and sulphate from wastewaters with an anaerobic attached-growth bioreactor.

Some industrial wastewaters may contain ammonium-nitrogen and/or sulphate, which need to be removed before their discharge into natural water bodies to eliminate their severe pollution. In this paper, simultaneous removal of ammonium-nitrogen and sulphate with an anaerobic attached-growth bioreactor of 3.8 L incubated with sulphate reducing bacteria (SRB) was investigated. Artificial wastewater containing sodium sulphate as electron acceptor, ammonium chlorine as electron donor and glucose as carbon source for bacteria growth was used as the feed for the bioreactor. The loading rates of ammonium-nitrogen, sulphate and COD were 2.08 gN/m3 x d, 2.38 gS/m3 x d, 104.17 gCOD/m3 x d, respectively, with a N/S ratio of 1:1.14. The results demonstrated that removal rates of ammonium-nitrogen, sulphate and COD could reach 43.35%, 58.74% and 91.34%, respectively. Meanwhile, sulphur production was observed in effluent as well as molecular nitrogen in biogas, whose amounts increased with time substantially, suggesting the occurrence of simultaneous removal of ammonium-nitrogen and sulphate. This novel reaction provided the possibility to eliminate ammonium-nitrogen and sulphate simultaneously with accomplishment of COD removal from wastewater, making wastewater treatment more economical and sustainable.     

Strategy for olive mill wastewater treatment and reuse with a sewage plant in an arid region.

This study was conducted to evaluate the treatability of OMW (olive mill wastewater) with sewage and sewage sludge, which could supplement nutrients and microbes required for OMW treatment and reduce its possible toxicity. The amount of OMW added to an aeration tank was based on the loading difference between the designed and actual COD loads, while the amount added to anaerobic digestion for energy recovery was determined by CH4 production. The COD removal efficiencies were 70-85% for both systems. Compost of OMW with dried sewage sludge also showed a similar temperature profile without OMW addition. This strongly suggested that OMW can be treated at a sewage plant without pretreatment and the treated effluent can be reused in irrigation for an arid region.     

Combined effect of plate pulsation parameters and phenol concentrations on the phenol removal efficiency of a pulsed plate bioreactor with immobilized cells

Continuous aerobic biodegradation of phenol in synthetic wastewater with phenol at different concentrations (200, 300, 500, 800 and 900 ppm) was carried out in a pulsed plate column, which is used as a bioreactor with immobilised cells of Nocardia hydrocarbonoxydans (NCIM 2386) at a dilution rate of 0.4094 h(-1) and amplitude of 4.7 cm at various frequencies of pulsation (0, 0.25, 0.5, 0.75 and 1 s(-1)). The effect of frequency of pulsation on the steady state performance of the bioreactor for phenol biodegradation at different influent concentrations was studied. Percentage degradations were observed to be a combined effect of volumetric phenol loading, reactor residence time, mass transfer limitations and phenol inhibition effect. At 500 ppm influent phenol concentration the effect of frequencies of pulsation on the steady state percentage degradation at different amplitudes was studied. The percentage degradation increased with increase in frequency and almost 100% degradation was achieved at 0.75 s(-1), 0.5 s(-1) or 0.25 s(-1), with 3.3, 4.7 or 6.0 cm amplitudes respectively and hence the vibrational velocity (amplitude*frequency) was found to influence the steady state performance of the reactor. It was found that optimum vibrational velocities need to be fixed for maximum removal efficiency of the bioreactor depending on the influent phenol concentration.     

Occurrence of EPS in activated sludge from a membrane bioreactor treating municipal wastewater.

EPS are supposed to be among the causes of membrane fouling in membrane bioreactors (MBR). In this work they are measured as total proteins and total polysaccharides. Theoretical and empirical considerations of biomass membrane filtration lead to the conclusion that EPS in the water phase is decisive for the filterability of activated sludge. In this study therefore different ways of separating the water phase from the biomass are investigated, where a simple filtration over a paper filter turned out to be sufficient. Subsequently, a simple batch test set up was used to investigate the influence of substrate conditions on the amount of EPS in the water phase. Dilution of the biomass does not result in changes. Dilution together with substrate addition leads to an increase both in proteins and polysaccharides. Replacement of the water phase leads to no significant changes in protein concentration, but polysaccharide concentration may vary considerably. This phenomenon is more pronounced after replacement of the water phase and substrate addition.     

Biodegradation of high 4-chlorophenol concentrations in a discontinuous reactor fed with an optimally controlled influent flow rate.

This work presents the results of the application of an optimally controlled influent flow rate strategy to biodegrade, in a discontinuous reactor, high concentrations of 4-chlorophenol used as toxic compound model. The influent is fed into the reactor in such a way as to obtain the maximal degradation rate, thus avoiding the inhibition of the microorganisms. The optimal strategy was able to manage increments of toxic concentrations in the influent up to 7,000 mg 4CP/L without any problem. It was shown not only that higher concentrations of toxic could be treated, but also that a reduction in degradation time (around 52%) and in the supplied air volume was obtained.     

Removal of colour from a kraft pulp and paper mill effluent in Kenya using a combination of electrochemical method and phosphate rock.

A study was undertaken to remove colour from a kraft mill's treated effluent in Kenya and determine the suitability of phosphate rock to replace wood ash during the electrochemical process. The electrochemical method alone, electrochemical combined with alum (ELCAL), wood ash leachate (ELCAS) and phosphate rock (ELPHOS) solutions at a rate of 165 to 1000 g/m3 were tested. Effluent characteristics were determined after complete removal of colour. Same reduction rates of TS (85%) and TSS (89%) were recorded by ELCAS and ELPHOS. However, ELPHOS removed more COD (86 to 91%) and more BOD (85 to 92%) than ELCAS. Furthermore, the pH of ELPHOS treated solution was 9.3, within the Kenya Local Government's allowable limit. Power reduction with ELCAS and ELPHOS varied between 53 to 73% and 49 to 69% respectively but the difference was not statistically significant. Overnight aeration further improved the quality of ELCAS and ELPHOS treated effluent, reducing BOD and COD values to 0 mg/l. ELPHOS cost ($0.29/m3) was nevertheless three times higher than that of ELCAS ($0.10/m3), mainly because of free wood ash. ELPHOS did not also increase effluent phosphorus. It was therefore recommended that various ways be explored in making ELPHOS more economical to replace ELCAS.     

Performance comparison of a pilot-scale membrane bioreactor and a full-scale sequencing batch reactor with sand filtration: treatment of low strength wastewater from a northern Canadian Aboriginal Community.

Northern Aboriginal communities in Canada suffer from poor wastewater treatment. Treatment systems on 75% of Manitoban Aboriginal communities produce substandard effluent despite the presence of sophisticated treatment systems. A 200-litre, pilot-scale membrane bioreactor (MBR) was established on the Opaskwayak Cree Nation to investigate the feasibility of MBRs in mitigating Aboriginal wastewater treatment issues. The pilot system was remote controlled and monitored via the Internet using the program pcAnywhere. The community utilized two existing sequencing batch reactors (SBR) and three sand filters for wastewater treatment. The community wastewater was relatively weak and highly fluctuating which led to poorly settling sludge that readily fouled the sand filters. A comparison study between the MBR and SBR was undertaken from September to December 2003. Operated at a 10-hour hydraulic retention time and 20-day solids residence time, the MBR outperformed the SBR and sand filtration on BOD and suspended solids removal. Furthermore, the MBR showed high levels of nitrification despite relatively cold water temperatures.     

Economic valuation of reduction in nitrogen outflow from a paddy field area equipped with a recycling irrigation facility.

We estimated the reduction in nitrogen outflow load from a paddy field that had a recycling irrigation facility and, by using a replacement cost method, evaluated the economic effect of nitrogen removal by the paddy field during the irrigation period in the Yoshinuma region of Tsukuba City, Japan. The recycling ratio of outflow water (proportion of outflow reused) was 13.5%. The nitrogen (N) outflow load was reduced by about 45 kg ha(-1) by the N removal function of the paddy field and by about 39 kg ha(-1) by the recycling irrigation facility. The paddy field equipped with a recycling irrigation facility as an N removal facility was valued at 32.6 million Japanese yen (JPY) ha(-1) and 0.72 million JPY ha(-1) per year, which compare it with the construction and maintenance costs, respectively, of a water quality improvement facility. The recycling irrigation facility was costed at 17.3 million JPY ha(-1) for construction and 0.21 million JPY ha(-1) for maintenance per year. The cost for constructing and maintaining a recycling irrigation facility was 53% of the value of the paddy field area equipped with a recycling irrigation facility as an N removal facility.     

Simultaneous removal of organic and strong nitrogen from sewage in a pilot-scale BNR process supplemented with food waste.

As the sewerage system is incomplete, sewage in Korea lacks easily biodegradable organics for nutrient removal. In this country, about 11,400 tons of food waste of high organic materials is produced daily. Therefore, the potential of food waste as an external carbon source was examined in a pilot-scale BNR (biological nutrient removal) process for a half year. It was found that as the supply of the external carbon increased, the average removal efficiencies of T-N (total nitrogen) and T-P (total phosphorus) increased from 53% and 55% to 97% and 93%, respectively. VFAs (volatile fatty acids) concentration of the external carbon source strongly affected denitrification efficiency and EBPR (enhanced biological phosphorus removal) activity. Biological phosphorus removal was increased to 93% when T-N removal efficiency increased from 78% to 97%. In this study, several kinds of PHAs (poly-hydroxyalkanoates) in cells were observed. The observed PHAs was composed of 37% 3HB (poly-3-hydroxybutyrate), 47% 3HV (poly-3-hydroxyvalerate), 9% 3HH (poly-3-hydroxyhexanoate), 5% 3HO (poly-3-hydroxyoctanoate), and 2% 3HD (poly-3-hydroxydecanoate).