Packed cage rotating biological contactor system for treatment of cyanide wastewater

The aim of this work was to study the efficiency of the packed cage rotating biological contactor (RBC) system with synthetic wastewater (SWW) containing 800 mg/l BOD(5) with various cyanide residue concentrations and hydraulic loading time. The results showed that cyanide had a negative effect to both the system's efficiency and bio-film quality. An increase in cyanide concentration led to a decrease in bio-film growth and the consequent reduction in the removal efficiency of the system. Also, the effluent suspended solids (SS) of the system was increased with increasing cyanide concentrations because the bio-film detached from the media due to the toxicity of the cyanide residue. The system showed the highest COD, BOD(5), TKN and cyanide removal efficiencies of 94.0 +/- 1.6%, 94.8 +/- 0.9%, 59.1 +/- 2.8% and 95.5 +/- 0.6%, respectively, with SWW containing 5 mg/l cyanide under HRT of 8 days, while they were only 88.8 +/- 0.7%, 89.5 +/- 0.5%, 40.3 +/- 1.1% and 93.60 +/- 0.09%, respectively, with SWW containing 40 mg/l cyanide. In addition, the effluent ammonia, nitrite and nitrate were increased with increases in cyanide concentration or loading. However, the system with SWW containing the highest cyanide concentration of 40 mg/l showed almost constant COD and BOD(5) removal efficiencies of 89% and 90%, even when the system was controlled under the lowest HRT of 8 h.     

Advanced treatment of high-strength wastewater by a submerged bio-film process

A submerged bio-film process was studied as a tertiary treatment to decrease the BOD of secondary effluent from a combined chemical-biological treatment of high-strength wastewater to below the permitted limit (30 mg/l) for waste facilities in Japan. The operational conditions to keep the final effluent below 30 mg/l of BOD were as follows: the influent BOD to the bio-film tank should be under 300 mg/l and a BOD-surface loading should be below 2 g/m²/d. The influent pH of 9.0–12.5 did not affect the treatment efficiency unfavorably. Acclimation is the compensating factor for variations of pH in this process. Removal rates of suspended solids were not influenced by BOD-surface loading. The calculated BOD removal coefficient was 2.57 × 10⁻⁵ when the influent BOD was below 300 mg/l.     

Removal of Pb2+ and Ni2+ by bio-sludge in sequencing batch reactor (SBR) and granular activated carbon-SBR (GAC-SBR) systems

Living bio-sludge from domestic wastewater treatment plant was used as adsorbent of heavy metals (Pb(2+), Ni(2+)) and its adsorption capacity was about 10-30% reduced by autoclaving at 110 degrees C for 10 min. The living bio-sludge acclimatized in synthetic industrial estate wastewater (SIEWW) without heavy metals showed the highest Pb(2+) and Ni(2+) adsorption capacities at 840+/-20 and 720+/-10 mg/g bio-sludge, respectively. The adsorbed Pb(2+) and Ni(2+) were easily eluted (70-77%) from bio-sludge by washing with 0.1 mol/l HNO(3) solution. The heavy metals (Pb(2+), Ni(2+)) removal efficiency of both SBR and GAC-SBR systems were increased with the increase of hydraulic retention time (HRT), or the decrease of organic loading. The SBR system showed higher heavy metals removal efficiency than GAC-SBR system at the same organic loading or HRT. The Pb(2+), Ni(2+), BOD(5), COD and TKN removal efficiencies of GAC-SBR system were 88.6+/-0.9%, 94.6+/-0.1%, 91.3+/-1.0%, 81.9+/-1.0% and 62.9+/-0.5%, respectively with industrial estate wastewater (IEWW) with 410 mg/l glucose, 5 mg/l Pb(2+) and 5 mg/l Ni(2+) under organic loading of 1.25 kg BOD(5)/m(3) d (HRT of 3 days). The bio-sludge quality (sludge volume index: SVI) of the system was less than 80 ml/g. The excess sludge from both SBR and GAC-SBR systems with SIEWW under the organic loading of 1.25-2.50 kg BOD(5)/m(3) d contained Pb(2+) and Ni(2+) at concentrations of 240-250 mg Pb(2+)/g bio-sludge and 180-210 mg Ni(2+)/g bio-sludge, respectively.     

Organic and nitrogen removal in a two-stage rotating biological contactor treating municipal wastewater

A laboratory scale rotating biological contactor (RBC) predenitrification system incorporating anoxic and aerobic units was evaluated for the treatment of settled high-strength municipal wastewater. The system was operated under four recycle ratios (1, 2, 3 and 4) and loading rates of 38-182 gCOD/m(2)d and 0.22-14 gOxid-N/m(2)d on the anoxic unit and 3.4-18 gCOD/m(2)d and 0.24-1.8 gNH(4)-N/m(2)d on the aerobic. The average removal efficiency in terms of chemical oxygen demand (COD), biochemical oxygen demand (BOD(5)), total suspended solids (TSS) and total nitrogen (Total-N) was 82%, 86%, 63% and 54%; settling of the RBC effluent increased COD and TSS removal to 94% and 97%. An increase in hydraulic loading resulting from higher recirculation, had limited negative effect on organic removal but improved nitrogen removal, and in terms of Total-N removal efficiency increased up to a ratio of 3 and then decreased.     

煤渣-草炭基质垂直流人工湿地系统对城市污水的净化效果

垂直流人工湿地系统不但具有较高的水力负荷率(54—64cm.^-1),而且对有机物和N、P都具有较高的去除效果．其对化粪池出水中的COD、BOD5、NIA4^+-N和总P的去除率分别为76％--87％,88％--92％,75％--85％和77％--91％．处理出水中COD、BOD5、NH4^+-N和总P的平均浓度分别小于60、20、25和2．0mg.L^-1.植物种植试验结果表明,种植风车草可提高氨氮、总N和总P的去除率,分别为2％--3％、4％--6％、10％--14％．     

Removal of disperse dyes from textile wastewater using bio-sludge

Granular activated carbon (GAC) did not show any significant adsorption ability on the disperse dyes, while resting (living) bio-sludge of a domestic wastewater treatment plant showed high adsorption abilities on both disperse dyes and organic matter. The dye adsorption ability of bio-sludge increased by approximately 30% through acclimatization with disperse dyes, and it decreased by autoclaving. The deteriorated bio-sludge could be reused after being washed with 0.1N NaOH solution. Disperse Red 60 was more easily adsorbed onto the bio-sludge than Disperse Blue 60. The Disperse Red 60, COD, and BOD5 adsorption capacities of acclimatized, resting bio-sludge were 40.0+/-0.1, 450+/-12, and 300+/-10mg/g of bio-sludge, respectively. The GAC-SBR system could be applied to treat textile wastewater (TWW) containing disperse dyes with high dye, BOD5, COD, and TKN removal efficiencies of 93.0+/-1.1%, 88.0+/-3.1%, 92.2+/-2.7% and 51.5+/-7.0%, respectively without any excess bio-sludge production under an organic loading of 0.18 kg BOD5/m3-d. Furthermore, the removal efficiencies increased with the addition of glucose into the system. The dye, BOD5, COD, and TKN removal efficiencies of the GAC-SBR system with TWW containing 0.89 g/L glucose were 94.6+/-0.7%, 94.4+/-0.6%, 94.4+/-0.8% and 59.3+/-8.5%, respectively, under an SRT of 67+/-0.4 days.     

Feasibility of using constructed wetland treatment for molasses wastewater treatment

The surface flow constructed wetland (SFCW) with Cyperus involucratus, Typha augustifolia and Thalia dealbata J. Fraser was applied to treat anaerobic treated-molasses wastewater (An-MWW) under the organic loading rates (OLRs) of 612, 696, 806, 929 and 1,213 kg BOD(5)ha(-1)day(-1). The results showed that both removal efficiency and plant growth rate were increased with the decrease of organic loading rate (OLR). All tested-plant species could not grow under OLR of higher than 696 kg BOD(5)mg l(-1) (p>0.05). Also, the plant-biomass of the systems was reduced by 10.4%, 26.5%, and 64.7% of initial plant-biomass under the OLR of 806, 929 and 1,213 kg BOD(5)ha(-1)day(-1), respectively. However, all tested-plant species showed the same pattern on the plant-biomass production yield and removal efficiency. The highest SS, BOD, COD, total phosphorus, NH(4)(+), NO(3)(-) and molasses pigments (MP) removal efficiencies of 90-93%, 88-89%, 67%, 70-76%, 77-82%, 94-95% and 72-77%, respectively were detected under the OLR of 612 kg BOD(5)ha(-1)day.     

人工湿地对猪场废水有机物处理效果的研究

分别以香根草 (Vetiveriazizanioides)和风车草 (Cyperusalternifolius)为植被 ,按 1.0m× 0 .5m×0 .8m建立人工湿地 ,通过 4季测试 ,研究其对猪场废水有机物的净化功能及其随季节、进水浓度及水力停留时间变化的规律 .结果表明 ,4个季节香根草或风车草人工湿地对COD和BOD有较稳定的去除效果 ,两湿地抗有机负荷冲击能力强 .在春季 ,停留时间 1～ 2d ,COD和BOD去除率分别为 70 %和 80 %;在夏季 ,进水COD高达 10 0 0～ 140 0mg·L-1情况下 ,COD去除率接近 90 %;在秋季 ,停留时间 1～ 2d ,COD和BOD去除率分别为 5 0 %～ 6 0 %和 5 0 %;在冬季 ,进水COD达 10 0 3mg·L-1情况下 ,COD去除率在 70 %以上 .COD、BOD和SS的去除率在两湿地间没有显著差异 .人工湿地污染物 (Y)随水力停留时间 (t)延长的降解遵从指数方程规律Yt=Y0 ·e( -kt) .在相同停留时间时 ,随进水污染物浓度 (x)提高的出水污染物浓度 (y)的回归关系遵从直线方程规律 y =a+bx .     

Treatment of tomato processing wastewater by an upflow anaerobic sludge blanket-anoxic-aerobic system

The main objective of this study is to assess the achievability of stringent discharge criteria i.e. BOD(5)<15 mg/L, TSS<15 mg/L and NH(4)-N<1mg/L during the treatment of tomato processing wastewater with COD of 2800-15,500 mg/L, BOD(5) of 1750-7950 mg/L, TKN of 48-340 mg/L and NH(4)-N of 21-235 mg/L. Two treatment systems, a UASB-aerobic system and a UASB-anoxic-aerobic system were tested. Furthermore due to alkalinity deficiency, in the raw wastewater, the study explored varying UASB effluent recirculation flowrates to the UASB influent to reduce additional alkalinity requirements. The UASB-anoxic-aerobic system was effective in treating tomato canning wastewater at an overall HRT of 1.75 days while achieving 98.5% BOD(5), 95.6% COD, 84% TSS and 99.5% NH(4)-N removal producing effluent BOD(5), COD, TSS, NH(4)-N, TKN, NO(2)-N, NO(3)-N and PO(4)-P of 10, 70, 15, 0.5, 3, 0, 60 and 4 mg/L, respectively. The biogas yield was 0.43 m(3)/kg COD removed.     

Enhanced removal of organic matter and ammoniacal-nitrogen in a column experiment of tidal flow constructed wetland system

A tidal flow constructed wetland system was investigated for the removal of organic matter and ammoniacal-nitrogen from diluted piggery wastewater. The results demonstrated that the operation of tidal flow enhanced the transfer of oxygen into wetland matrices. The supply of oxygen by the operation (473 gO2/m2d) matched the demand for wastewater treatment. The overall oxygen consumption rate in the system was considerably higher than the typical rate obtainable in conventional wetlands; most oxygen being used for the decomposition of organic matter. Compared with conventional systems, the tidal flow system demonstrated greater efficiency in the removal of organic matter. Significant nitrification did not take place, although 27-48% ammonia was removed from the wastewater. Immobilization by microbial cells and adsorption were the likely routes to remove ammonia under the specific experiment conditions. Percentage removals of BOD5, NH4-N and SS increased after effluent recirculation at a ratio of 1:1 was employed.     

Some properties of a sequencing batch reactor system for removal of vat dyes

Bio-sludge from a wastewater treatment plant could be used as an adsorbent of vat dye from textile wastewater. Resting bio-sludge gave a higher adsorption capacity than dead bio-sludge. The resting bio-sludge from a textile wastewater treatment plant gave relatively high COD, BOD5 and dye adsorption capacity of 364.4 +/- 4.3, 178.0 +/- 9.0 and 50.5 +/- 1.3 mg/g of bio-sludge, respectively, in synthetic textile wastewater containing 40 mg/l Vat Yellow 1. Another advantage of the bio-sludge was that, after washing with 0.1 N NaOH solution, it was reusable without any activity loss. Through treatment with a sequencing batch reactor (SBR) system, both organic and dye in STIWW could be removed. The maximum dye (Vat Yellow 1), COD, BOD5 and TKN removal efficiencies of the SBR system under an MLSS of 2000 mg/l and an HRT of three days were 98.5 +/- 1.0%, 96.9 +/- 0.7%, 98.6 +/- 0.1% and 93.4 +/- 1.3%, respectively. Although, the dye and organic removal efficiencies of the SBR system with real textile wastewater were quite low, they could be increased by adding organic matters, especially glucose. The dye, COD, BOD5 and TKN removal efficiencies of the SBR system with glucose (0.89 g/l) supplemented textile industrial wastewater were 75.12 +/- 1.2%, 70.61 +/- 3.4%, 96.7 +/- 0.0%, and 63.2 +/- 1.1%, respectively.     

Degradation of 4-chlorophenol in UASB reactor under methanogenic conditions

Treatment of simulated wastewater containing 40 mg/l of 4-chlorophenol (4-CP) was carried out in an upflow anaerobic sludge blanket (UASB) reactor under methanogenic condition. The performance of this test UASB reactor was evaluated in terms of 4-CP removal. Hydraulic retention time (HRT) and substrate:co-substrate ratio for the 4-CP removal was optimized by varying the influent flow rate (13-34.7 ml/min) and sodium acetate concentration (2-5 g/l), respectively. A control UASB reactor, which was not exposed to 4-CP was also operated under similar conditions. Organic loading rate (OLR) was varied in the range of 2-5.3 kg/m(3)/d and 1.7-4.2 kg/m(3)/d, respectively, for HRT and substrate:co-substrate ratio studies, respectively. The optimum HRT and substrate:co-substrate ratio for the removal of 4-CP was 12h and 1:75, respectively. Removal of 4-CP achieved at optimum HRT and substrate:co-substrate ratio was 88.3+/-0.7%. Removal of 4-CP occurred through dehalogenation and caused increase in chloride ion concentration in the effluent by 0.23-0.27 mg/mg 4-CP removed. The ring cleavage test showed the ortho mode of ring cleavage of 4-CP. Change in the elemental composition of the anaerobic biomass of UASB reactors was observed during the study period. Concentration of Ca(2+) increased in the biomass and this could be attributed to the biosoftening. Specific methanogenic activity of the sludge of control and test UASB reactor was 0.832 g CH(4) COD/g VSS d and 0.694 g CH(4) COD/g VSS d, respectively.     

Methane emission potential and increased efficiency of a phytoremediation system bioaugmented with Bacillus firmus XJSL 1-10

Horizontal subsurface flow constructed wetland mesocosms (HSSCW) designed to treat municipal waste water were bioaugmented with Bacillus firmus XJSL 1-10. The efficiencies of the three HSSCW mesocosms (non-vegetated HSSCW, Schoenoplectus validus HSSCW and Bambusa vulgaris HSSCW) were assessed. Bioaugmentation not only enhanced the efficiency of the phytoremediation system but also reduced methane emission from an average of 51.3 mg/m2/d to 21.6 mg/m2/d in Schoenoplectus validus HSSCW and from an average of 1708 mg/m2/d to 1473 mg/m2/d in Bambusa vulgaris HSSCW. Each of the three types of bioaugmented HSSCWs showed higher purification efficiency with respect to the removal of BOD and NH4-N than the non-bioaugmented HSSCWs. The performance enhancement was most significant in bioaugmented Schoenoplectus validus HSSCW mesocosm with 48.8 and 44.8% lower BOD, and NH4-N, respectively than the non-bioaugmented HSSCW.     

Feasibility study of a pilot-scale sewage treatment system combining an up-flow anaerobic sludge blanket (UASB) and an aerated fixed bed (AFB) reactor at ambient temperature

A feasibility test of a 17 m3-pilot-scale sewage treatment system was carried out by continuous feeding of raw municipal sewage under ambient temperature conditions. The system consisted of a UASB and an aerated fixed bed reactor. Some of the effluent from the fixed bed reactor was returned to the UASB influent in order to provide a sulfate source. The total BOD of 148-162 mg l(-1) in the influent was reduced to a more desirable 11-25 mg l(-1) in the final effluent. The levels of methane-producing activity from acetate and H2/CO2 gas at 10 degrees C were only 2% and 0% of those at 35 degrees C, respectively. On the other hand, the sulfate-reducing activity levels of the UASB sludge were relatively high at 10 degrees C, for example, 18% for acetate and 9% for H2/CO2 gas, compared to the activity levels at 35 degrees C. Therefore, BOD oxidization by sulfate reduction in the UASB was greater than that by methane production under low temperature conditions. This sulfate-reducing activity tended to be proportional to the copy number of adenosine-5'-phosphosulfate (APS) reductase genes in DNA extracted from the sludge.     

Removal of Zn2+ and Cu2+ by a sequencing batch reactor (SBR) system

Both resting (living) and autoclaved (dead) bio-sludges showed almost the same Cu2+ and Zn2+ adsorption capacities with synthetic industrial estate wastewater (SIEWW). The resting bio-sludge showed not only Cu2+ and Zn2+ adsorption abilities but also organic matter adsorption ability. But, the organic matter (COD and BOD5) adsorption ability of bio-sludge with SIEWW containing 60 mg/L Cu2+ was about half of that with SIEWW containing 60 mg/L Zn2+. The adsorbed Cu2+ and Zn2+ were easily eluted (70-75%) from bio-sludge with 0.1 N HNO3 and 0.1 M EDTA solutions. Bio-sludge from a wastewater treatment plant could be used as an adsorbent for metal ions (Cu2+ and Zn2+). Cu2+ and Zn2+ could repress the SBR system efficiency but its efficiency could be increased with the increase of mixed liquor suspended solids (MLSS), and Cu2+ had more effect than Zn2+ to repress the system efficiency. The SBR system showed very low removal efficiencies of the pollutants with industrial estate wastewater (IEWW), but its pollutant removal efficiencies with IEWW could be increased with the addition of glucose. The Zn2+, Cu2+, BOD5, COD and TKN removal efficiencies of the system with IEWW containing 1.27 g/L glucose, 10 mg/L Cu2+ and 10 mg/L Zn2+ under MLSS of 4500 mg/L were 92.61 +/- 0.28%, 83.77 +/- 0.93%, 98 +/- 0%, 92 +/- 0% and 78.1 +/- 0.1%, respectively.     

Combined biological and membrane treatment of food-processing wastewater to achieve dry-ditch criteria: pilot and full-scale performance

This study tested the applicability of a submerged vacuum ultrafiltration membrane technology in combination with the biological treatment system to achieve dry-ditch criteria stipulated as follows: BOD5, TSS, NH3-N, and total phosphorous (TP) concentration not exceeding 10, 10, 1, and 0.5 mg/L respectively for the treatment of high strength food-processing wastewater. During the study, the biological system, operated at average hydraulic retention time of 5-6 days, achieved 95-96.5% BOD removal and 96-99% COD removal. The external membrane system ensured the achievability of the BOD and TSS criteria, with BOD and TSS concentrations in the permeate of 1-2 and 1-8 mg/L respectively. Nitrate, and nitrite concentrations increased during membrane filtration, while ammonia concentrations decreased. The most salient finding of this study is that, contrary to common belief, for industrial wastewaters, the filterability of the mixed liquor is influenced by the soluble organics, and may be low, thus necessitating operation of bioreactors at low mixed liquor solids. This study demonstrated that bioreactors operated at low SRTs and in combination with ultrafiltration can still achieve superior effluent quality that may meet reuse criteria at reasonable cost.     

Anaerobic treatment of distillery spent wash - a study on upflow anaerobic fixed film bioreactor

Anaerobic digestion of wastewater from a distillery industry having very high COD (1,10,000-1,90,000 mg/L) and BOD (50,000-60,000 mg/L) was studied in a continuously fed, up flow fixed film column reactor using different support materials such as charcoal, coconut coir and nylon fibers under varying hydraulic retention time and organic loading rates. The seed consortium was prepared by enrichment with distillery spent wash in a conventional type reactor having working capacity of 3 L and was used for charging the anaerobic column reactor. Amongst the various support materials studied the reactor having coconut coir could treat distillery spent wash at 8d hydraulic retention time with organic loading rate of 23.25 kg COD m(-3)d(-1) leading to 64% COD reduction with biogas production of 7.2 m3 m(-3)d(-1) having high methane yield without any pretreatment or neutralization of the distillery spent wash. This study indicates fixed film biomethanation of distillery spent wash using coconut coir as the support material appears to be a cost effective and promising technology for mitigating the problems caused by distillery effluent.     

Nutrient recovery from domestic wastewater using a UASB-duckweed ponds system

The pilot-scale wastewater treatment system used in this study comprised a 40-l UASB reactor (6-h HRT) followed by three duckweed ponds in series (total HRT 15 days). During the warm season, the treatment system achieved removal values of 93%, 96% and 91% for COD, BOD and TSS, respectively. Residual values of ammonia, TKN and total phosphorus were 0.41 mg N/l, 4.4 mg N/l and 1.11 mg P/l, with removal efficiencies of 98%, 85% and 78%, respectively. The system achieved 99.998% faecal coliform removal during the warm season with final effluent containing 4 x 10(3) cfu/100 ml. During the winter, the system was efficient in removing COD, BOD and TSS but not nutrients. The system was deficient in the removal of faecal coliforms during the winter, producing effluent with 4.7 x 10(5) cfu/100 ml. During the warm season, the N removal consisted of 80% by plant uptake, 5% by sedimentation and 15% unaccounted for. A duckweed production rate of 33 t dry matter per hectare per 8 months was achieved.     

再生水用于地下回灌过程中有机物的迁移和去除

人工地下水回灌是解决我国水资源短缺的有效途径之一.在实验室利用土壤柱系统,考查了回灌过程中有机物的迁移和去除.二级处理出水经活性碳吸附后进入土壤柱系统,土壤柱系统对TOC、UV-254和BOD₅的去除率分别为44%、34.36%和95%,并且大部分有机物是在土壤表层0～0.5 m被去除的.进水TOC浓度为9～11 mg·L^-1时,回灌过程中TOC浓度随土壤柱深度的变化符合指数方程：C=10e^-0.6934h(R²=0.8697). 用该方程可以较好地预测土壤柱出水中的TOC浓度.     

Effects of hydraulic loading rate on pollutants removal by a deep subsurface wastewater infiltration system

The subsurface wastewater infiltration (SWI) system proved to be an effective and low-cost technique for decentralized sewage treatment in areas without adequate domestic treatment facilities. Field-scale experiments were conducted through a deep SWI system, with effective depth of 1.5 m, under hydraulic loading rates of 0.040, 0.065, 0.081 and 0.10 m³/m² d. Taking the hydraulic and treatment efficiencies into consideration, the hydraulic loading rate of 0.081 m³/m² d was recommended. Under this condition, NH₃-N, TN, and COD removal efficiencies were 86.2 ± 3.0, 80.7 ± 1.9 and 84.8 ± 2.1%, respectively. In the effluent, NH₃-N concentration declined to 2.3-4.4 mg/L, accounting for 63.2-65.6% of TN. NO₃-N concentration increased from 0.2 to 0.3 mg/L in the influent to 2.0-2.5 mg/L in the effluent. The nitrifying bacteria number declined with increased depth, while the amount of denitrifying bacteria increased. The analysis of results about the nitrifying and denitrifying bacteria distribution indicated that the most effective ranges for nitrification and denitrification process were 0.3-0.7 m and 0.7-1.5 m, respectively.