Biobleaching of Pulp and Paper Mill Effluents by Phanerochaete chrysosporium

The potential of white rot fungi, namely, Polyporus versicolor FRI 165, Polyporus hirsutus FRI 534, Polyporus hirsutus FRI 2862, Phanerochaete chrysosporium BKMF 1767 and Sporotrichum pulverulentum for the reduction of colour of pretreated pulp and paper mill effluents under sterilised and unsterilised conditions has been evaluated. Of these, P. chrysosporium BKMF 1767 cultured under sterilised conditions supported maximum colour reduction after 7 days of growth. The optimisation of the process parameters showed that the addition of nutrient sails in selective combination marginally improved the colour reduction. The 7-day-old growth of culture at 20% (v/v) inoculum concentration resulted in maximum decolourisation (69.6%) of the effluent with pH adjusted to 4.5 at 40°C along with more than 50% reduction in biological oxygen demand (BOD) and chemical oxygen demand (COD). The irradiation of the effluent with UV light had apparently no effect on the colour, BOD and COD reduction by P. chrysosporium.     

Ozonation as a Treatment for Mechanical And Chemical Pulp Mill Effluents

Eighteen effluent types from seven thermomechanical (TMP), chemithermomechanical (CTMP), bleached chemimechanical (BCMP), and kraft pulp mills were treated in the laboratory with ozone alone or ozone in conjunction with aerobic biological treatment. Except for one mechanical pulp mill effluent, all effluents ozonized showed rapid and selective destruction of their acute toxicity, juvabiones (JB), and resin and fatty acids (RFAs) over biological and chemical oxygen demand (BOD and COD) by ozone. For acute toxicity and RFA/JB removal, aerobic biotreatment of mechanical mill effluent streams produced additive but not synergistic effects when combined with ozone treatment. Ozonation of biotreated kraft effluents yielded substantial decreases in the biologically recalcitrant residual adsorbable organic halogens (AOX), converted COD to BOD, and usually produced large decreases in color.     

Removal of chemical oxygen demand from textile wastewater using a natural coagulant

A biomaterial was successfully synthesized from Plantago ovata by using an FeCl₃-induced crude extract (FCE). The potential of FCE to act as a natural coagulant was tested for the pretreatment of real textile wastewater. Tests were performed to evaluate the effects of FCE quantity, salt concentration, and wastewater pH on chemical oxygen demand (COD) reduction during a coagulation/flocculation process. Experimental results indicated that the wastewater could be effectively treated by using a coagulation/flocculation process, where the BOD₅/COD ratio of the effluent was improved to 0.48. A low coagulant dose, 1.5mg/L, achieved a high COD removal percentage, 89%, at operational conditions of neutral pH and room temperature. The experimental data revealed that the maximum COD removal occurred at water pH<8. Increasing the salt promoted the COD removal. The settling and filterability characteristics of the sludge were also studied. Scanning electron microscopy and energy dispersive spectroscopy studies were conducted to determine the sludge structure and composition, respectively. Overall, FCE as an eco-friendly biomaterial was revealed to be a very efficient coagulant and a promising option for the removal of COD from wastewaters.     

Integrated ozone–photo–Fenton process for the removal of pollutant from industrial wastewater

The use of hybrid advanced oxidation processes(AOPs) for the removal of pollutants from industrial effluents has been extensively studied in recent literature. The aim of this study is to compare the performance of the photo,Fenton, photo-Fenton and ozone–photo–Fenton processes in terms of color removal and chemical oxygen demand(COD) removal of distillery industrial effluent together with the associated electrical energy per order. It was observed from the experimental results that the O_3/UV/Fe~(2 +)/H_2O_2 process yielded a 100% color and95.50% COD removals with electrical energy per order of 0.015 k W·h·m~(-3) compared to all other combinations of the AOPs. The effects of various operating parameters such as H_2O_2 and Fe~(2+) concentration, effluent pH, COD concentration and UV power on the removal of color, COD and electrical energy per order for the ozone–photo–Fenton process was critically studied and reported. The color and COD removals were analyzed using a UV/Vis spectrometer and closed reflux method.     

Processing of biscuit industrial effluent using thin film composite nanofiltration membranes

Nanofiltration (NF) is a membrane-based separation process having significant potential for the treatment of industrial effluents to enable water reuse. It has the ability to remove low molecular weight trace contaminants from water, which cannot be separated by conventional treatment methods. In the present investigation, a thin film composite polyamide membrane was synthesized by interfacial polymerization technique and evaluated for the treatment of biscuit industrial effluent. The synthesized membrane was characterized using Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy to elucidate structure and intermolecular interactions, crystallinity, thermal stability and cross-sectional morphology, respectively. The influence of operating parameters such as feed pressure 0–21 kg/cm² and total dissolved solids (TDS) of 3160 ppm on water flux and impurity rejection was determined. An average flux of 11.63 L/m² h was obtained at a constant pressure of 21 kg/cm². The TDS, chemical oxygen demand (COD), and biochemical oxygen demand (BOD) rejections were found to be 53.62, 80, and 74%, respectively, at a water recovery of 65%. A statistical mechanical model was used to validate the experimental data. Based on this study, a detailed economic estimation for processing biscuit effluent of 1 m³/h feed capacity using commercial NF system is presented. The study revealed that the synthesized NF membrane could be an effective alternative for the treatment of various industrial effluents as well as to reduce the load on reverse osmosis process for desalination of seawater and effluent treatment through high degree of COD and BOD separation.     

Effect of Ozone Pretreatment on Biodegradability Enhancement and Biogas Generation Potential From Biomethanated Distillery Effluent

The study evaluates the effect of ozone pretreatment on biodegradability enhancement of biomethanated distillery effluent. Results revealed that ozone pretreatment led to biodegradability index (BI = BOD/COD) enhancement up to 0.58 along with COD, color and toxicity reduction of up to 33%, 25% and 40%, respectively. Anaerobic digestion of pretreated effluent resulted in favorable biogas generation with methane content, yield and COD reduction of up to 62%, 39 mL/g COD and 57%, respectively. Kinetics of biogas generation determined by modified Gompertz model indicated methane production potential and production rate of 48.08 mL/g COD and 8.085 mL/g COD.day respectively under optimal conditions.     

Anaerobic biogas generation from sugar industry wastewaters in three‐phase fluidized‐bed bioreactor

In the present study, attempts are made to optimize digestion time, initial feed pH, feed temperature, and feed flow rate (organic loading rate, OLR) for maximum yield of methane gas and maximum removal of chemical oxygen demand (COD) and biological oxygen demand (BOD) of sugar industry wastewaters in three‐phase fluidized‐bed bioreactor. Methane gas is analysed by using flame‐ionisation detector (FID). The optimum digestion time is 8 h and optimum initial pH of feed is observed as 7.5. The optimum temperature of feed is 40°C and optimum feed flow rate is 14 L/min with OLR 39.513 kg COD/m³ h. OLR is calculated on the basis of COD inlet in the bioreactor at different flow rates. The maximum methane gas concentration is 61.56% (v/v) of the total biogas generation at optimum biomethanation process parameters. The maximum biogas yield rate is 0.835 m³/kg COD/m³ h with maximum methane gas yield rate (61.56%, v/v) of 0.503 m³/kg COD/m³ h at optimum parameters. The maximum COD and BOD reduction of the sugar industry wastewaters are 76.82% (w/w) and 81.65% (w/w) at optimum biomethanation parameters, respectively.     

Integration of continuous biological and chemical (ozone) treatment of domestic wastewater: 1. Biodegradation and post‐ozonation

The continuous treatment of domestic wastewater by an activated sludge process and by an integrated biological–chemical (ozone) oxidation process were studied in this work. Chemical oxygen demand (COD), biochemical oxygen demand (BOD), absorbance at 254 nm (UV₂₅₄) and nitrogenous compound content were the parameters followed in order to evaluate the performance of the two processes. Experimental data showed that both UV₂₅₄ and COD reductions are improved in the combined biological–chemical oxidation procedure. Thus, reductions of 59.1% and 37.2% corresponding to COD and UV₂₅₄, respectively were observed after the biological process (hydraulic retention time = 5 h; mixed liquor volatile suspended solids concentration = 3142 g m⁻³) compared with 71.0% and 78.4% obtained when a post‐ozonation step ( D _O3 = 41.7 g m⁻³) was included. During conventional activated sludge treatment, appropriate nitrification levels are only achieved with high hydraulic retention time and/or biomass concentration. Ozonation after the secondary treatment, however, allows improved nitrogen content reduction with total nitrite elimination. Post‐ozonation also leads to a higher biodegradability of the treated wastewater. Thus, the ultimate BOD/COD ratio goes from 0.16 after biological oxidation to 0.34 after post‐ozonation with 41.7 g O₃ m⁻³. © 1999 Society of Chemical Industry     

混凝-Fenton-SBR联用工艺处理印刷线路板乳化废液

采用混凝-Fenton-SBR法处理印刷线路板乳化废液,实验结果表明,采用聚合氯化铁(PFC),在pH值为6.3,投加量为2800mg/L的条件下,COD去除率约为80.9%。混凝后废水利用Fenton处理,在pH=3时,H2O2用量为50g/L,FeSO4·7H2O的用量为5g/L时,废水COD降为1342mg/L,BOD降为657mg/L,废水的可生化性指数为0.49,可利用SBR处理,生化出水COD浓度低于485mg/L,可达到《广东省水污染物排放限值》(DB44/26-2001)中COD的三级排放标准。     

Biodegradation kinetics of the soluble slowly biodegradable substrate in polyamide carpet finishing wastewater

BACKGROUND: Carpet manufacturing and finishing with purely synthetic fibers has received relatively little attention, compared to other textile processing types. This study evaluates the biodegradation kinetics of organic compounds generated from polyamide‐based carpet manufacturing. RESULTS: Experiments were conducted on pre‐washing and dyeing/softening wastewater effluents. Model evaluation of oxygen uptake rate profiles with dual hydrolysis kinetics revealed that the soluble slowly hydrolysable chemical oxygen demand (COD) was the major fraction, constituting nearly 97% of the biodegradable COD and 78% of total COD content. Degradation of the slowly hydrolysable COD fraction was characterized with a rate coefficient of 0.72 day^?1, a significant rate limiting step for substrate utilization. Model simulation of system performance indicated that an unusually long hydraulic retention time was required for an activated sludge system to reduce the effluent COD concentration. CONCLUSION: Compared to domestic wastewater, two additional hydrolysable COD fractions with different degradation kinetics were characterized. The dyeing and softening step had the highest slowly biodegradable organic matter content, with the lowest degradation rate. Simulation results showed that soluble slowly hydrolysable COD degradation did not cause any problem in terms of effluent quality. With the system operated under reduced solids retention time, the effluent COD quality was significantly influenced by the slow hydrolysis rate of soluble hydrolysable matter. Copyright © 2007 Society of Chemical Industry     

用UV/H2O2,UV/O3,UV/H2O2/O3催化处理城市固体垃圾填埋渗出物

The performance of UV/H2O2, UV/O3, and UV/H2O2/O3 oxidation systems for the treatment of municipal solid-waste landfill leachate was investigated. Main objective of the experiment was to remove total organic carbon (TOC), non-biodegradable organic compounds (NBDOC) and color. In UV/H2O2 oxidation experiment, with the increase of H2O2 dosage, removal efficiencies of TOC and color along with the ratio of biochemical oxygen demand (BOD) to chemical oxygen demand (COD) of the effluent were increased and a better performance was obtained than the system H2O2 alone. In UV/H2O2 oxidation, under the optimum condition H2O2 (0.2 time), removal efficiencies of TOC and color were 78.9% and 95.5%, respectively, and BOD/COD ratio was significantly increased from 0.112 to 0.366. In UV/O3 oxidation, with the increase of O3 dosage, removal efficiencies of TOC and color along with BOD/COD ratio of the effluent were increased and a better performance was obtained than the system O3 alone. Under the optimum condition UV/O3     

木薯酒精废液的达标处理研究

经过TLP-GXEM厌氧技术处理后的木薯酒精废液COD的质量浓度从22 000～35 000 mg/L降到2 000～3 000 mg/L,BOD5与COD的质量比约为0.6,生化性良好。再采用SBR工艺进行后续处理,在进水COD、BOD5的质量浓度分别为2 450、1 350 mg/L,色度为225倍时,出水COD、BOD5的质量浓度分别降为300～500、60￣90 mg/L,色度降为220倍左右。由于好氧出水的可生化性很差,选用活性炭吸附作为深度处理,可以使废水COD降为100 mg/L以下,活性炭对COD的去除率达到了85%,并且脱色效果明显,出水的色度为8倍左右,活性炭对色度去除率高达96.4%,两者均达到污水综合排放标准一级排放标准。     

Effect of Low Temperatures on the Performance of an Anaerobic Baffled Reactor (ABR)

The effect of a decrease in operating temperature on the performance of two 10 dm³ anaerobic baffled reactors (ABR) was examined in terms of steady state chemical oxygen demand (COD) removal efficiency. To minimise variations, and have a totally biodegradable feed, a synthetic carbohydrate (sucrose)–protein (meat extract) substrate was used. The reactors were operated at 20 h hydraulic retention time (HRT), 4 g dm⁻³ COD, and 35°C as a base-line condition. Because of their different histories, the reactors responded differently to a decrease in operating temperature to 25°C. Reactor 1 remained stable at 97% COD removal, whereas Reactor 2 decreased to 93% removal, but rose to 97% after adding an effluent recycle of 0·25. At 15°C, the efficiency of Reactor 1 dropped to 75%, while the removal of Reactor 2 declined to 83%, and no improvement in efficiency occurred with an effluent recycle at 0·25. At 25°C, the decreased rate of catabolism of the slow-growing syntrophs and methanogens resulted in a shift of the volatile fatty acids (VFA) peak to the second compartment. However, the biomass present in the reactor prevented VFAs breaking through in the effluent. Nevertheless, at 15°C VFAs were present in the effluent, perhaps due to the lower rates of metabolism and an increase in the K_s for VFAs. Finally, at 15°C part of the increase in the effluent COD was due to the enhanced production of soluble microbial products (SMP), or a decrease in their metabolism, with these compounds constituting some 10% of the inlet COD. © 1997 SCI.     

Treatment of high‐fat‐containing dairy wastewater in a sequential UASBR system: influence of recycle

BACKGROUND: Raw cheese whey originating from white cheese production results in a strong and complex wastewater excessively rich in organic matter (chemical oxygen demand, COD = 28–65 g L^?1), fatty matter (14–24.5 g L^?1) and acidity (3.9–6.1 g L^?1). It was treated in a three‐stage configuration consisting of a pre‐acidification (PA) tank and sequential upflow anaerobic sludge bed reactors (UASBRs) at 2.8–7 g COD L^?1 day^?1 organic loading rates, during which the effects of effluent recycling at low rates and promoted SRB activity were investigated. Acidification, volatile fatty acids (VFA), COD and fatty matter removal and volatile solids were monitored throughout the system during the study. RESULTS: Recycling of the effluent promoted VFA and COD removal as well as pH stability in both stages of the UASBRs and the effluent where high alkalinity levels were recovered reducing alkali requirement to 0.05 g OH g^?1 COD_applied. Higher removal rates of 71–100 and 50–92% for VFA and COD were obtained by use of recycling. Fatty matter was removed at 63–89% throughout the study. Volatile solids build‐up was significant in the inlet zones of the UASBRs. CONCLUSIONS: The system produced efficient acidification in the PA tank, balanced pH levels and an effluent high in alkalinity and BOD/COD ratio. Efficient VFA removal and solids immobilization was obtained in both stages up to the highest loading rate. Recycling improved the system performance under high fatty matter loading conditions. A major advantage of the sequential system was that the second stage UASBR compensated for reduced performance in the first stage. Copyright © 2010 Society of Chemical Industry     

萘胺废水处理工程的设计与运行

萘胺废水具有CODCr浓度高、酚浓度高的特点。采用Fe-C微电解工艺对其进行预处理,CODCr去除率大于30%,酚去除率大于60%,m(BOD5):m(CODCr)从0.11提高0.32。预处理后的废水经二级生化处理,在混合废水CODCr、BOD5、挥发酚的质量浓度分别为1 548、496、59 mg/L时,处理后出水分别为112、15、0.2 mg/L,出水水质达到G8 8978-1996《污水综合排放标准》之二级标准。     

Simultaneous removal of Pb(II) and chemical oxygen demand from aqueous solution using immobilized microorganisms on polyurethane foam carrier

We studied the simultaneous removal of Pb(II) and chemical oxygen demand (COD) from synthetic solutions using immobilized microorganism. The immobilized microorganisms on polyurethane foam (IPUF) were successfully prepared by cultivating the microbe B350 in a mixture of culture medium and polyurethane foam (PUF). The adsorption of Pb(II) ion from aqueous solutions onto PUF and IPUF was studied by batch adsorption. IPUF exhibited high Pb(II) removal efficiency. When 0.12 g of IPUF was used to treat 50mL of 20mg/L P(II) solution at pH 7.0 and 25 °C for 120 mins, the removal ratio was 80%. The biosorption kinetics could be described by the pseudo-secondorder model, and the adsorption isotherms could be described by Langmuir and Freundlich equations. In addition, for synthetic wastewater containing Pb(II) and C₆H₁₂O₆, the removal ratios of Pb(II) and COD after being treated by IPUF for 8 hours were 92.0% and 84.2%, respectively. The removal ratio of COD clearly decreased with the increase of Pb(II) concentration, meaning that Pb(II) was toxic to the mobilized microorganisms and lower Pb(II) concentration was preferred.     

Treatment of a combined dairy and domestic wastewater in an up-flow anaerobic sludge blanket (UASB) reactor followed by activated sludge (AS system)

The feasibility of using an up-flow anaerobic sludge blanket (UASB) reactor followed by activated sludge (AS system) for the treatment of wastewater discharged from dairy factory was explored. The UASB reactor was operated at a hydraulic retention time (HRT) of 24 h and organic loading rates (OLRs) ranging from 1.9 to 4.4 kgCOD/m³.d. The average total chemical oxygen demand (COD_total) and total biological oxygen demand (BOD_5total) concentrations of the UASB reactor effluent were 1385 and 576 mg/l, corresponding to percentage removal of 69% and 79%, respectively. Total suspended solids (TSS) and volatile suspended solids (VSS) removal averaged above 72% and 75%, respectively. Residual phosphorous and oil and grease concentrations of the UASB reactor effluent were 8.2 and 44 mg/l, corresponding to percentage removal values of 63% and 83%, respectively. This good performance could be attributed to the relatively long sludge residence time (SRT = 76 d) imposed to the reactor. Total and faecal coliform counts were reduced in the treated effluent by a value of 1.07 and 0.9 log₁₀, respectively. The net sludge yield coefficient was found to be 0.2 g VSS per g COD_total removed per day, corresponding to 20% of the total influent COD imposed to the UASB reactor. The volatile solids / total solids (VS/TS) ratio of 0.66 of excess sludge revealed its good quality. Preliminary batch experiments of the AS system treating UASB reactor effluent indicated first-order removal kinetics between total organic carbon (TOC) and contact time. The TOC removal reached 80%, resulting in only 47 mg/l in the final effluent at a HRT of 2.0 h. Accordingly, the AS system was operated at a HRT of 2.0 h. The system achieved a substantial reduction of COD_total, BOD_{5 total}, TSS and oil and grease resulting effluent quality with residual values of only 35.0, 7.0, 14.0 and 2.8 mg/l, respectively. The geometric mean of total and faecal coliform counts was reduced by a value of 1.28 and 1.64 log₁₀, respectively. Based on these results, it is recommended to use of an integrated system consisting of a UASB reactor followed by the AS system for the treatment of a combined dairy and domestic wastewater to produce a good effluent quality complying with the standards for discharge into agricultural drains.     

OPTIMIZATION OF PROCESS CONDITIONS USING RESPONSE SURFACE METHODOLOGY (RSM) FOR ETHANOL PRODUCTION FROM WASTE CASHEW APPLE JUICE BY ZYMOMONAS MOBILIS

Ethanol has been known for a long time, being perhaps the oldest product obtained through traditional biotechnology. It is an attractive, sustainable energy source for fuel additives. Based on a four-level central composite design (CCD) involving the variables substrate composition (20–100%) X₁, pH (4.5–6.5) X₂, incubation temperature (28°–36°C) X₃, and fermentation time (12–60 h) X₄, a response surface methodology (RSM) for the production of ethanol using waste cashew apple juice as substrate by Zymomonas mobilis MTCC 090 was standardized. The design contains a total of 31 experimental trials with the first 16 organized in a fractional factorial design and 25 to 31 involving the replications of the central points. Data obtained from RSM on ethanol production were subjected to the analysis of variance (ANOVA) and analyzed using a second-order polynomial equation, which resulted in the optimized process conditions of 62% (v/v) as substrate concentration, pH of 5.5, temperature of 32°C, and fermentation time of 37 h. Maximum ethanol concentration (12.64 g/L) was obtained at the optimized conditions in an anaerobic batch fermentation.     

接触氧化-混凝沉淀法处理秸秆气化气洗涤水

报道了好氧、混凝处理工艺处理秸秆气化气洗涤水。好氧段采用生物接触氧化法，混凝处理工艺采用聚合氯化铝作混凝剂进行试验。结果表明，水质参数为CODcr814mg/L、BOD5 302mg/L、酚类38mg/L的原水经批处理工艺后相应的参数降为CODcr140mg/L、BOD5 17mg/L、酚类0．4mg/L，去除率分别为82．8％、93％、98．9％。出水水质达到国家二级排放标准（GB8978－1996）。     

Effect of ozonation on chemical oxygen demand fractionation and color profile of textile wastewaters

Filtration and ultrafiltration with a size range of 2–1600 nm were used to evaluate the effect of ozonation on the particle size distribution‐based chemical oxygen demand (COD) and color profiles of textile wastewater before and after biological treatment. Ozonation induced a net effect of 9% COD reduction in the influent and 15% in the effluent. However, a more in‐depth evaluation based on particle size distribution and mass balance for the influent revealed different mechanisms of ozonation, which were interpreted as total oxidation in the soluble range, replenishment of soluble COD through solubilization of organics into simpler compounds and polymerization towards the upper size range (>220 nm). For the biological treatment effluent, the greatest effect of ozonation was in the lower particle size range (<8 nm). Ozone was very effective for color removal, giving 80–93% optical density reductions in the influent and 96–99% in the effluent, depending on the excitation wavelength selected. Ozonation of the influent removed practically all color fractions, except in the particulate range. In the effluent, the particulate fraction was removed by biological treatment and settling and consequently the remaining color were almost entirely removed by ozonation. Copyright © 2005 Society of Chemical Industry