曝气生物滤池处理工业综合废水提标改造技术研究

针对化学合成制药含铜黄连素废水特点,设计了铁碳微电解和离子交换组合工艺为预处理工艺,开展了小试与中试试验研究。结果表明,采用铁碳微电解池-离子交换柱组合工艺连续处理初始CODCr浓度为60 000-80 000 mg/L、黄连素浓度为1 700-1 900 mg/L、Cu2+浓度为12 000-18 000 mg/L的含铜黄连素制药废水,小试试验对黄连素和Cu2+的去除率都在99.0%以上,出水黄连素和Cu2+在1.0 mg/L和0.5 mg/L以下。中试试验对CODCr的去除率在44.0%以上,Cu2+的去除率超过79.0%。处理每吨水可回收12～13 kg铜。该工艺有较好的废水预处理效果,实现了金属铜资源化回收,可有效减少对后续废水生化处理工艺的压力。     

Removal of tungsten oxyanions from industrial wastewater by precipitation, coagulation and flocculation processes

Tungsten removal from industrial wastewater by precipitation, coagulation and flocculation processes using ferric chloride is reported. Suitable process conditions (pH, ferric chloride concentration) were established in jar tests performed with wastewater samples. Alkaline wastewater was treated with ferric chloride and pH was adjusted to various points using sulphuric acid. Tungsten removal was found to be most efficient (98-99%) in acidic conditions (pH<6). The process conditions were also found to be suitable for operation of an industrial scale wastewater treatment facility. More than 97% of tungsten were removed and the residual concentration was smaller than 10 ppm.     

Recovery of copper and water from copper-electroplating wastewater by the combination process of electrolysis and electrodialysis

In this paper, a laboratory-scale process which combined electrolysis (EL) and electrodialysis (ED) was developed to treat copper-containing wastewater. The feasibility of such process for copper recovery as well as water reuse was determined. Effects of three operating parameters, voltage, initial Cu(2+) concentration and water flux on the recovery of copper and water were investigated and optimized. The results showed that about 82% of copper could be recovered from high concentration wastewater (HCW, >400mg/L) by EL, at the optimal conditions of voltage 2.5 V/cm and water flux 4 L/h; while 50% of diluted water could be recycled from low concentration wastewater (LCW, <200mg/L) by ED, at the optimal conditions of voltage 40 V and water flux 4 L/h. However, because of the limitation of energy consumption (EC), LCW for EL and HCW for ED could not be treated effectively, and the effluent water of EL and concentrated water of ED should be further treated before discharged. Therefore, the combination process of EL and ED was developed to realize the recovery of copper and water simultaneously from both HCW and LCW. The results of the EL-ED process showed that almost 99.5% of copper and 100% of water could be recovered, with the energy consumption of EL ≈ 3 kW h/kg and ED ≈ 2 kW h/m(3). According to SEM and EDX analysis, the purity of recovered copper was as high as 97.9%.     

Treatment of desizing wastewater by catalytic thermal treatment and coagulation

In the present study, the coagulation of the fresh and thermally treated desizing wastewater has been reported. The maximum COD reduction of fresh desizing wastewater using coagulation was observed with commercial alum at initial pH 4. This was followed by aluminum potassium sulfate (pH 4), FeCl(3) (pH 6), PAC (pH 6) and FeSO(4) (pH 4). The maximum COD reduction observed at a coagulant (commercial alum) dose of 5 kg/m(3) and pH 4 was 58% whereas the color reduction at these conditions was 85%. The results reveal that the application of coagulation on the catalytic thermal treated effluent is more effective in removing nearly 88% of COD and 96% of color at above mentioned conditions except at a coagulant dose of 1 kg/m(3). The amount of inorganic sludge generated gets drastically reduced (almost 25%) due to the reduced amount of coagulant. The COD and color of the final effluent were found to be 98.6 mg/l and 2.67 PCU, respectively, and the COD/BOD(3) ratio was 1.36. The settling rate of the slurry was found to be strongly influenced by treatment pH. The slurry obtained after treatment at pH 12 settled faster in comparison to slurry obtained at pH 4. The filterability of the treated effluent is also strongly dependent on pH. pH 12 was adjudged to be the best in giving highest filtration rate.     

Treatment of jean-wash wastewater by combined coagulation, hydrolysis/acidification and Fenton oxidation

Performance of a full-scale combined treatment plant for jean-wash wastewater (JWW) was investigated. The combined process consisted of chemical coagulation, hydrolysis/acidification and Fenton oxidation. Chemical coagulation treatment with polymeric ferric sulfate (PFS)/lime alone proved to be effective in removing the COD (>70%) and part of the color (>50%) from the JWW. Fenton oxidation combined with hydrolysis/acidification as pretreatment offered a noticeable BOD removal efficiency. The average removal efficiencies for COD, BOD, SS, color and aromatic compounds of the combined process were about 95%, 94%, 97%, 95% and 90%, respectively, with the average effluent quality of COD 58 mg/L, BOD 19 mg/L, SS 4 mg/L and color 15(multiple), consistent with the national discharge limits for textile wastewater. The result indicated that the combined procedure could offer an attractive solution for JWW treatment with considerable synergistic advantages.     

混凝-陶瓷膜微滤处理阴极电泳漆废水研究

提出用混凝与陶瓷膜微滤组合工艺处理阴极电泳漆废水的方法,研究了pH值对CODCr去除率的影响,操作压差、膜面流速对膜通量的影响,得到了适宜的操作条件和有效的膜清洗方法.结果表明:料液pH值为6.7时,混凝过程对CODCr去除率的贡献约63%,之后的微滤使废水中CODCr的去除率增加到85%.采用平均孔径为0.2μm的氧化锆膜,在膜面流速4.2 m/s,压差0.10 MPa,温度30℃,膜稳定通量约250 L/(m2.h),渗透液可作为涂装车间循环冲洗水用.混凝作为前处理过程有助于提高膜的渗透通量,降低膜污染,改善出水水质.     

Advanced treatment of coking wastewater by coagulation and zero-valent iron processes

Advanced treatment of coking wastewater was investigated experimentally with coagulation and zero-valent iron (ZVI) processes. Particular attention was paid to the effect of dosage and pH on the removal of chemical oxygen demand (COD) in the two processes. The results showed that ZVI was more effective than coagulation for advanced treatment of coking wastewater. The jar tests revealed that maximal COD removal efficiency of 27.5-31.8% could be achieved under the optimal condition of coagulation, i.e. 400mg/L of Fe(2)(SO(4))3 as coagulant at pH 3.0-5.0. On the other hand, the COD removal efficiency could be up to 43.6% under the idealized condition of ZVI upon 10 g/L active carbon and 30 g/L iron being dosed at pH 4.0. The mechanisms for COD removal in ZVI were dominated by coagulation, precipitation and oxidation-reduction. ZVI would also enhance the biodegradability of effluent by increasing BOD5/COD from 0.07 to 0.53. Moreover, some ester compounds could be produced in the reaction. Although ZVI was found more efficient than coagulation in eliminating low molecular weight (<2000 Da) compounds in the wastewater, there were still a few residual contaminants which could hardly be eliminated by either of the process.     

Algae-based sorbents for removal of gallium from semiconductor manufacturing wastewater

Removal of various soluble metallic impurities from wastewater in semiconductor fabrication plants is a critical issue facing the microelectronics industry. Considering the large volume of wastewater and a highly variable concentration of these contaminants, finding a robust adsorption process using a low-cost sorbent is of great value and interest to this industry. Of particular interest is the development of a flow-through abatement method for treating the process-tool effluent before it is mixed with other wastewaters. In this work, a strain of freshwater green algae (Chlorella sorokiniana), representing an algae-based sorbent, and a simulated wastewater, containing soluble gallium as the metallic impurity, are used as model compounds. The choice of gallium is based on its increased use, and the lack of related adsorption data compared to the information available for other metals such as copper and arsenic. Both batch and continuous-flow operations were used in this study. Comprehensive process models were developed and validated for both batch and flow systems. These models were found to be valuable for understanding the process steps as well as for obtaining the fundamental parameters that are needed for process design and scale-up. The sorbent was found to have high adsorption capacity even at low pH values (14.1 mg/g at pH of 2.3, and 38.5 mg/g at pH of 2.8). Based on the comparison of adsorption rate and capacity with data on previously studied and conventional sorbents, such as activated carbon and ion-exchange resins, the use of this algae-based sorbent is potentially an attractive option for the removal of gallium from the process-tool wastewater.     

Treatment of bactericide wastewater by combined process chemical coagulation, electrochemical oxidation and membrane bioreactor

Bactericide wastewater (BIW) contains isothiazolin-ones, high salinity, toxicity and non-biodegradable organic concentrations. In order to enhance biodegradable capacity, chemical coagulation and electrochemical oxidation were applied to pretreatment processes. FeSO(4).7H2O, pH 12 and 20 mmol/l were determined as optimal chemical coagulation condition; and 15 mA/cm2 of current density, 10 ml/min of flow rate and pH 7 were chosen for the most efficient electrochemical oxidation condition at combined treatment. The wastewater which consisted mainly of isothiazolin-ones and sulfide was efficiently treated by chemical coagulation and electrochemical oxidation. The optimal pretreatment processes showed 60.9% of chemical oxygen demand (COD), 99.5% of S(2-) and 96.0% of isothiazolin-ones removal efficiency. A biological treatment system using membrane bioreactor (MBR) adding powder-activated carbon (PAC) was also investigated. COD of the wastewater which was disposed using a MBR was lower than 100 mg/l.     

Treatment of composite wastewater of a cotton textile mill by thermolysis and coagulation

Catalytic thermal treatment (thermolysis) accompanied with coagulation was used for the removal of COD and color of composite wastewater from a cotton textile mill. CuSO4, FeSO4, FeCl3, CuO, ZnO and PAC were used as catalytic agents during thermolysis. Homogeneous copper sulphate at a mass loading of 6 kg/m3 was found to be the most active. Similarly during coagulation aluminum potassium sulphate [KAl(SO4)(2).16H2O] at a coagulant concentration of 5 kg/m3 was found to be the best among the other coagulants tested, namely, commercial alum, FeSO4, FeCl3 and PAC. During thermolysis, a reduction in COD and color of composite wastewater of about 77.9 and 92.85%, respectively, was observed at pH 12. Coagulation of fresh composite waste using aluminum potassium sulphate resulted in 88.62% COD reduction and 95.4% color reduction at pH 8. Coagulation of the supernatant obtained after treatment by catalytic thermolysis resulted in overall reduction of 97.3% COD and close to 100% color reductions at pH 8 at a lesser coagulant concentration of 3 kg/m3. The results reveal that the application of coagulation after thermolysis is most effective in removing nearly 100% of COD and color at a lower dose of coagulant. The sludge thus produced would contain lower inorganic mass coagulant and can be used as a solid fuel with high calorific value of about 16 MJ/kg, close to that of Indian coal.     

Reduction of organic matter and trihalomethane formation potential in reclaimed water from treated industrial estate wastewater by coagulation

Raw water from treated industrial estate wastewater in northern Thailand was used in jar-test coagulation experiments with variations of separate alum and ferric chloride dosages from 10 to 80 mg/L at pH conditions ranging from 5 to 6.5. Natural organic matter (NOM) surrogates and trihalomethane formation potential (THMFP) were determined to study their reduction. The obtained results showed that total organic carbon (TOC) were gradually reduced from the average value of about 6.1 mg/L to a level of about 4.0 mg/L by alum and ferric chloride dosages of approximately 40 mg/L. Moreover, dissolved organic carbon (DOC) were reduced from an average value of 5.1 mg/L to a level of about 4.0 mg/L by alum and ferric chloride dosages of approximately 40 mg/L. Specific ultraviolet absorption (SUVA) were decreased from an average value of approximately 4.7 L/mgm to a level of about 2 L/mgm by alum and ferric chloride dosages of approximately 20 mg/L. In addition, chlorine demands at 1 day reaction were the same as those of 7-day demands with a correlation coefficient of 0.98 (n = 10, correlation significant at the 0.01 level). Interestingly, chloroform of approximately 65 and 60% of total THMFP was found as the predominant THMFP species in treated industrial estate wastewater and reclaimed water, respectively, in comparison with other THM species. Maximum THMFP percentage removal of 25 and 28 by using alum and ferric chloride dosages of about 80 mg/L at pH 5.5 and 5 were obtained, respectively, at the examined conditions.     

铁碳微电解预处理印染废水的强化技术研究

采用铁、碳材料组成微电池电解处理工业印染废水,考察了铁、碳材料的用量比、pH值等因素对印染废水处理效果的影响。试验结果表明：m（铁）：m（碳）：1：4、pH3．5时效果最好。在此基础上,以6m3／（m3·min）的通气量进行强化曝气可进一步增强催化效果,当印染废水COD浓度为2000mg／L时,其去除率可达92．5％。     

Treatment of water-based printing ink wastewater by Fenton process combined with coagulation

Attempts were made in this study to examine the efficiency of Fenton process combined with coagulation for treatment of water-based printing ink wastewater. Parameters affecting the Fenton process, such as pH, dosages of Fenton reagents and the settling time, were determined by using jar test experiments. 86.4% of color and 92.4% of chemical oxygen demand (COD) could be removed at pH 4, 50mg/l H(2)O(2), 25mg/l FeSO(4) and 30min settling time. The coagulation using polyaluminium chloride (PAC) and ferrous sulfate (FeSO(4)) was beneficial to improve the Fenton process treated effluent in reducing the flocs settling time, enhancing color and COD removal. The overall color, COD and suspended solids (SS) removal reached 100%, 93.4% and 87.2% under selected conditions, respectively. Thus this study might offer an effective way for wastewater treatment of water-based ink manufacturer and printing corporation.     

Tungsten and other heavy metal contamination in aquatic environments receiving wastewater from semiconductor manufacturing

Through analyses of water and sediments, we investigate tungsten and 14 other heavy metals in a stream receiving treated effluents from a semiconductor manufacturer-clustered science park in Taiwan. Treated effluents account for ～ 50% of total annual river discharge and <1% of total sediment discharge. Dissolved tungsten concentrations in the effluents abnormally reach 400 μg/L, as compared to the world river average concentration of <0.1 μg/L. Particulate tungsten concentrations are up to 300 μg/g in suspended and deposited sediments, and the corresponding enrichment factors are three orders of magnitude higher than average crust composition. Surprisingly, the estimated amount of tungsten exported to the adjacent ocean is 23.5 t/yr, which can approximate the amount from the Yangtze River should it be unpolluted. This study highlights the urgency of investigating the biological effect of such contamination.     

离子膜电解去除味精废水中氨氮的研究

采用离子膜电解法对高浓度氨氮废水进行脱氨预处理,对影响氨氮去除的几种因素进行了研究.6 V、60℃下去除率在75%以上.脱除的氨氮以浓氨水的形式回收,实现废物资源化.废水经脱氨后出水基本无色,COD也有一定降低.综合考虑能耗后,得出本实验条件下适宜的操作条件,去除率平均接近64%,为工业化应用提供了依据.     

Decolorization and COD reduction of dyeing wastewater from a cotton textile mill using thermolysis and coagulation

The decolorization and reduction of COD of dyeing wastewater from a cotton textile mill was conducted using catalytic thermal treatment (thermolysis) accompanied with/without coagulation. Thermolysis in presence of a homogeneous copper sulphate catalyst was found to be the most effective in comparison to other catalysts (FeCl(3), FeSO(4), CuO, ZnO and PAC) used. A maximum reduction of chemical oxygen demand (COD) and color of dyeing wastewater of 66.85% and 71.4%, respectively, was observed with a catalyst concentration of 5 kg/m(3) at pH 8. Commercial alum was found most effective coagulant among various coagulants (aluminum potassium sulphate, PAC, FeCl(3) and FeSO(4)) tested during coagulation operations, resulting in 58.57% COD and 74% color reduction at pH 4 and coagulant dose of 5 kg/m(3). Coagulation of the clear fluid (supernatant) obtained after treatment by thermolysis at the conditions previously used resulted in an overall reduction of 89.91% COD and 94.4% color at pH 4 and a coagulant dose of 2 kg/m(3). The application of thermolysis followed by coagulation, thus, is the most effective treatment method in removing nearly 90% COD and 95% color at a lower dose of coagulant (2 kg/m(3)). The sludge thus produced would contain lower inorganic mass coagulant and, therefore, less amount of inorganic sludge.     

Method of obtaining gallium from aluminate solution by electrolysis

Abstract

Gallium is an increasingly important material in the fields of semiconductors and energy transfer. A prime source of gallium is the aluminate solution that remains after the purification of bauxite. The authors have sought a way of reclaiming gallium economically by electrolysis of a laboratory aluminate solution without having to use a cathode of mercury – an environmental pollutant. Cathodes of copper, indium, 70In–30Ga, Wood's alloy, and mercury (for comparison) were used with a wide range of anodes. The study accounted for the effects of electrode material, temperature, current density, and initial gallium concentration on the yield, energy consumption, and utilization of both current and electrode. The best results were obtained with indium or In–Ga cathodes and with platinum, Pt–Ti, or stainless steel anodes, at 75°C and a current density of ~100 Am^?2. Electrolysis was more efficient the higher the gallium concentration, demonstrating that commercial–scale electrolysis of aluminate solution is unlikely to be economically viable without prior concentration of gallium.

MST/305     

Feasibility investigation of oily wastewater treatment by combination of zinc and PAM in coagulation/flocculation

Poly-zinc silicate (PZSS) is a new type of coagulant with cationic polymer synthesized by polysilicic acid and zinc sulfate. It has been used in several sorts of wastewaters treatment, but not used in oily wastewater treatment. In this study, we investigated the coagulation/flocculation of oil and suspended solids in heavy oil wastewater (HOW) by PZSS and anion polyacrylamide (A-PAM). The properties of PZSS cooperated with A-PAM were compared with PAC and PFS in dosages, PAMs amount, settling time, pH value and flocs morphology. The results showed that PZSS was more efficient than PAC and PFS. Under the optimum experimental conditions of coagulation/flocculation (dosage: 100mg/L, A-PAM dosage: 1.0mg/L, settling time time: 40min and pH 6.5-9.5), more than 99% of oil was removed and suspended solid value less than 5mg/L by using PZSS cooperated with A-PAM, which could satisfy the demands of the pre-treatment process for HOW to be reused in the steam boiler or recycled into the injecting well.     

Arsenic removal from a high-arsenic wastewater using in situ formed Fe-Mn binary oxide combined with coagulation by poly-aluminum chloride

In this study, in situ formed Fe-Mn binary oxide (FMBO) was applied to treat a practical high-arsenic wastewater (5.81 mg/L). FMBO exhibited a remarkable removal capacity towards both As(III) and As(V), achieving a removal efficiency over 99.5%. However, the FMBO-As particles could not be sufficiently separated by gravitational sedimentation due to their low sizes and negative charges, as being indicated from laser particle size and zeta-potential analysis. Thus, poly-aluminum chloride (PACl) was introduced as a coagulant to facilitate the solid-liquid separation, and it remarkably improved As removal efficiencies. Results of scanning electron microscope (SEM) revealed that PACl contributed to the formation of precipitates with larger sizes and compact surfaces, which was favorable to sedimentation. Moreover, residual soluble As was removed by PACl hydroxides. The optimum dosages of FMBO and PACl were determined to be 60 mg/L and 80 mg/L, respectively. Additionally, the secondary pollution was minimized in FMBO-PACl process. Based on these bench-scale results, a full-scale treatment process was proposed to successfully treat 40,000 m(3) of high-arsenic wastewater in a municipal wastewater treatment plant (MWWTP). The average As concentration in the effluent was about 0.015 mg/L. FMBO-PACl process showed the advantages of high effectiveness, low cost, safety, and ease for operation.     

Isolation and identification of novel high strength phenol degrading bacterial strains from phenol-formaldehyde resin manufacturing industrial wastewater

Phenols are toxic to all types of organisms. Two bacterial strains capable of utilizing phenol as a sole carbon source were isolated from the phenol bearing industrial wastewater. Based on the biochemical test results the organisms were identified as Pseudomonas cepacia and Bacillus brevis. The organisms were very efficient in phenol degradation, the lag phase increased with increase in phenol concentration. The well-acclimatized cultures of P. cepacia and B. brevis degraded 2500 and 1750 mg l(-1) of phenol in 144 h, respectively. The organisms degrade phenol even in the presence of toxicants like thiocyanate, sulphide and cyanide. The organisms can be effectively used for treating high strength phenol containing thiocyanate, sulphide and cyanide. The P. cepacia degrades phenol with a faster rate than B. brevis. P. cepacia can be used effectively for treating high strength phenolic wastewater.