基于不同碳源的硫酸盐还原菌处理硫酸盐酸性废水试验

为探究硫酸盐还原菌(sulfate reducing bacteria,SRB)在不同碳源条件下还原硫酸盐的最佳pH值条件及其还原动力学过程,分别以甘蔗渣和乳酸钠为碳源,负载SRB处理含硫酸盐酸性废水。结果表明:以甘蔗渣、乳酸钠为碳源,SRB均在pH为6时对硫酸盐的去除效果最佳,最大去除率分别为71. 82%、85. 31%,体系氧化还原电位分别为-242、-164 m V;而在pH为4条件下,SRB对硫酸盐的去除效果甘蔗渣优于以乳酸钠为碳源的体系,对硫酸盐最大去除率分别为49. 04%、36. 24%,体系氧化还原电位分别为-229、-57 mV;两种碳源条件下,SRB还原SO_4~(2-)的过程都符合一级动力学模型,在以甘蔗渣为碳源、pH为6的体系中,其最大还原速率分别为0. 20007/d、0. 12688/d。     

组合膜分离技术资源化处理印染废水工艺的研究

为解决印染废水的资源化处理问题,针对实际印染废水研究了以超滤和纳滤膜分离技术为核心的印染废水处理及回用工艺在工程上的可行性。实验结果表明:还原染料废水采用超滤系统处理,膜出水水质即能够满足印染厂内回用水质要求;活性染料废水通过纳滤浓缩能够获得较好的染料回收效果。采用双膜膜分离系统(UF+NF)能够使两种染料废水的污染物均得到明显去除,还原性染料废水的总悬浮物、COD、浊度和色度的去除率达到了100%、95.21%、92.86%和100%;活性染料废水上述各项指标去除率达到100%、82.85%、98.46%和99.43%。双膜膜分离系统适用于工业印染废水处理及染料回收,是资源化处理印染废水的发展方向。     

The effect of the textile industry dye bath additive EDTMPA on colour removal characteristics by ozone oxidation.

In this study, the effects of the phosphonic acid based sequestering agent EDTMPA used in the textile dye baths on colour and organic matter removal by ozone oxidation was experimentally investigated. Procion Navy HEXL dyestuff that has been commonly used for the reactive dyeing of cellulose fibers was selected as the model component. The organic matter oxidation by ozone was determined to obey the pseudo-first order kinetics as they are treated singly or in combination. COD removal rates obtained from pseudo-first order reaction kinetics showed that oxidation of Navy HEXL alone (0.0947 L/min) was faster than that of EDTMPA (0.0171 L/min) and EDTMPA with dye (0.0155 L/min) at pH 3.0. It was also found that reaction rates of single EDTMPA removal and EDTMPA and dye mixture removal increased as the reaction pH was increased from 3.0 to 10.5.     

粉末状骨炭用于饮用水除氟的试验研究

对粉末状骨炭的除氟性能进行了多组试验研究,结果表明:粉末状骨炭的吸附容量与原水中氟离子的浓度呈线性关系,吸附等温式符合Freundlich公式。骨炭吸附容量受骨炭粒径、pH值、水温及水中其他离子的影响,骨炭粒径还会影响吸附反应的速度。骨炭采用5%的NaOH溶液再生,再生效果良好。     

Bioremediation of direct dyes in simulated textile effluents by a paramorphogenic form of Aspergillus oryzae

Azo dyes are extensively used for coloring textiles, paper, food, leather, drinks, pharmaceutical products, cosmetics and inks. The textile industry consumes the largest amount of azo dyes, and it is estimated that approximately 10-15% of dyes used for coloring textiles may be lost in waste streams. Almost all azo dyes are synthetic and resist biodegradation, however, they can readily be reduced by a number of chemical and biological reducing systems. Biological treatment has advantages over physical and chemical methods due to lower costs and minimal environmental effect. This research focuses on the utilization of Aspergillus oryzae to remove some types of azo dyes from aqueous solutions. The fungus, physically induced in its paramorphogenic form (called 'pellets'), was used in the dye biosorption studies with both non-autoclaved and autoclaved hyphae, at different pH values. The goals were the removal of dyes by biosorption and the decrease of their toxicity. The dyes used were Direct Red 23 and Direct Violet 51. Their spectral stability (325-700 nm) was analyzed at different pH values (2.50, 4.50 and 6.50). The best biosorptive pH value and the toxicity limit, (which is given by the lethal concentration (LC(100)), were then determined. Each dye showed the same spectrum at different pH values. The best biosorptive pH was 2.50, for both non- autoclaved and autoclaved hyphae of A. oryzae. The toxicity level of the dyes was determined using the Trimmed Spearman-Karber Method, with Daphnia similis in all bioassays. The Direct Violet 51 (LC(100) 400 mg · mL(-1)) was found to be the most toxic dye, followed by the Direct Red 23 (LC(100) 900 mg · mL(-1)). The toxicity bioassays for each dye have shown that it is possible to decrease the toxicity level to zero by adding a small quantity of biomass from A. oryzae in its paramorphogenic form. The autoclaved biomass had a higher biosorptive capacity for the dye than the non-autoclaved biomass. The results show that bioremediation occurs with A. oryzae in its paramorphogenic form, and it can be used as a biosorptive substrate for treatment of industrial waste water containing azo dyes.     

Nutrient recovery from biomass cultivated as catch crop for removing accumulated fertilizer in farm soil

As a result of long-term continuous use of fertilizers in farm land, a large amount of nutrients accumulate in the soil, increasing the risk of eutrophication or nitrate pollution of groundwater. For rehabilitating the farm soil and recovering nutrients such as nitrogen, phosphorus and potassium, a new system has been developed by our research group. This paper discusses the methodology of extracting nutrients from biomass in order to recover phosphorus and other nutrients in crystal form. Around 80% or higher extraction rates were achieved for phosphorus and potassium by soaking the powdered tissue in distilled water or 1% NaOH solution for 24 h. The extracted phosphorus and potassium act as a potential resource for recycled fertilizer or other industrial materials.     

Removal of Ni(II) from aqueous solution using Moringa oleifera seeds as a bioadsorbent

Metal contaminants are generally removed from effluents by chemical and physical processes which are often associated with disadvantages such as the use of toxic reagents, generation of toxic waste and high costs. Hence, new techniques have been developed, among them the study of natural adsorbents, for instance, the use of Moringa oleifera seeds. The potential of M. oleifera seeds for nickel removal in aqueous systems was investigated. The seeds utilized were obtained from plants grown in Uberlandia/Brazil. After being dried and pulverized, the seeds were treated with 0.1 mol/L NaOH. Fourier transform infrared spectroscopy, scanning electron microscopy and thermogravimetric analyses were used for the characterization of the material. Using the optimized methodology (50 mL of 4.0 mg/L Ni(II), pH range of 4.0-6.0, agitation time of 5 min and adsorption mass of 2.0 g) more than 90% of Ni(II) could be removed from water samples. The sorption data were fitted satisfactorily by the Langmuir adsorption model. Evaluation applying the Langmuir equation gave the monolayer sorption capacity as 29.6 mg/g. The results indicate that this material could be employed in the extraction of nickel, considering its ease of use, low cost and environmental viability, which make it highly attractive for application in developing countries.     

Adsorption of allura red dye by cross-linked chitosan from shrimp waste

The present study was designed to evaluate the chitosan, which has been obtained by deacetylation of chitin, as a biosorbent. The chitin was isolated from fermented shrimp waste by an important local industrial food biopolymer. The aim of this work was the characterization of chitosan and preparation of cross-linked chitosan- tripolyphosphate (chitosan-TPP) beads for the removal of allura red food dye from aqueous solutions. Conditions of batch adsorption such as pH, time and adsorbent dose were examined. The effectiveness of cross-linked chitosan beads for dye removal was found to be higher for pH 2 (98%, percentage of dye removal) and tends to decrease at pHs of 3 to 11 (up to 49%). The values of percentage removal show that the adsorption capacity increases with time of contact and dosage of chitosan-TPP, but red dye adsorption is mainly influenced by pH level. The cross-linked chitosan-TPP beads can significantly adsorb allura red monoazo dye from aqueous solutions even at acidic pHs unlike raw chitosan beads that tend to dissolve in acidic solutions. Consequently, this modified chitosan has characteristics that allow minimization of environmental pollution and widening the valorization of shrimp waste.     

Adsorption kinetics, isotherms and thermodynamics of atrazine removal using a banana peel based sorbent

Atrazine removal from water by treated banana peels was studied. The effect of pH, contact time, initial atrazine concentration, and temperature were investigated. Batch experiments demonstrated that 15 g L(-1) adsorbent dosage removed 90-99% of atrazine from 1-150 ppm aqueous solutions. The removal was both pH and temperature dependent with the most atrazine removed between pH 7 and 8.2 and increased with increasing temperature. Equilibrium data fitted well to the Langmuir and Redlich-Peterson models in the concentration and temperature ranges investigated, with a maximum adsorption capacity of 14 mg g(-1). Simple mass transfer models were applied to the experimental data to examine the adsorption mechanism and it was found that both external mass transfer and intraparticle diffusion played important roles in the adsorption mechanisms. The enthalpy of atrazine adsorption was evaluated to be 67.8 ± 6.3 kJ mol(-l) with a Gibbs free energy of -5.7 ± 1.2 kJ mol(-1).     

The effect of nitrogen supplementation on the efficiency of colour and COD removal by Malaysian white-rot fungi in textile dyeing effluent.

White-rot fungi, namely Coriolus versicolor and Schizophyllum commune, were studied for the biodecolorization of textile dyeing effluent in shaker-flask experiments. The results showed that C. versicolor was able to achieve 68% color removal after 5 days of treatment while that of S. commune was 88% in 9 days. Both fungi achieved the above results in non-sterile condition with diammonium hydrogen phosphate as the nutrient supplement. On the other hand, the best COD removal of 80% was obtained with C. versicolor in 9 days in sterile effluent with yeast extract as nutrient supplement, while S. commune was able to remove 85% COD within 8 days in non-sterile textile effluent supplemented with diammonium hydrogen phosphate.     

MBR fouling control and permeate quality enhancement by polyaluminium chloride dosage: a case study

Scope of this study was to evaluate the effectiveness of a metal salt (polyaluminium chloride, PACl) dosage into a pilot-scale MBR (membrane bioreactor) in terms of fouling control and permeate quality enhancement, especially with reference to specific textile macro-pollutants (dyes and surfactants). The pilot plant was fed with a mixed domestic-textile wastewater (textile wastewater accounted for 65% of total flow and for 70% of total chemical oxygen demand, COD, load) and operated for 7.5 months without flux enhancers (step 1) and 3 months with the addition of PACl (step 2). The optimum dose was defined performing a jar-test campaign between step 1 and step 2 (12.5 mg gMLSS(-1) that corresponds to 0.4 g d(-1)). The addition of PACl resulted in a significant decrease of the filtration resistance due to cake layer formation (R(c), -65.4%) and of the irreversible fouling rate, evaluated as the average variation per unit time of the filtration resistance due to foulants adsorption on membrane pore wall (FR, -45.3%). As for permeate quality, removal rates related to total phosphorus and textile macro-parameters such as colour and anionic surfactants, increased by +64, +16 and +7%, respectively. No significant effect was observed on COD, non-ionic surfactants and nitrogen compounds removal.     

天然沸石的改性及其去除制革废水中铵的研究

通过加热以及用酸、碱、盐浸泡方式对天然沸石进行改性,用于模拟制革废水中铵的处理。结果表明:加热改性、H2SO4改性未能提高沸石对废水中铵的去除率,低浓度的HCl和NaOH改性可以提高沸石对铵的吸附效果,而高浓度的HCl和NaOH改性使吸附效果下降。NaCl改性能提高沸石对废水中铵的去除率,最佳改性条件为添加浓度为1.0~1.5 mol/L的NaCl溶液,温度70℃,时间3 h。改性后,沸石对铵的去除率达78%,比未改性前提高了15%左右。     

Membrane-flocculation-adsorption hybrid system in wastewater treatment: micro and nano size organic matter removal .

Cross flow microfiltration with in-line flocculation reduces the fouling of membranes thus leading to high quality product water. A detailed experimental study conducted with an artificial suspension (particle size distribution similar to that of surface water) revealed that the filtration rate can be increased by several times by adopting in-line flocculation. In-line flocculation-microfiltration is therefore an attractive technique to reduce internal clogging while improving the permeate flux significantly. A detailed ultrafiltration (UF) study was conducted with biologically treated sewage effluent with pretreatment by flocculation and powdered activated carbon adsorption. The TOC removal by the NTR 7410 UF membrane alone was 43.6%. The TOC removal increased significantly by the use of pretreatment: 69.3% by flocculation and 91% by flocculation followed by adsorption. The organic colloidal portion (between 3,500 dalton and 0.45 microm) in the biologically treated effluent was removed up to more than 65% by the pretreatment of flocculation. The molecular weight of the biologically treated effluent ranged from 250 to about 3,573 dalton with the highest fraction in the range of 250-845 dalton. By the incorporation of pretreatment, the majority of both large and small molecular weight organic matter was removed. This hybrid system led to practically no filtration flux decline in membrane filtration.     

Obtention of plant peroxidase and its potential for the decolorization of the reactive dye Remazol Turquoise G 133%

Peroxidases can be used in the decolorization process. There is a growing interest for new sources of this enzyme and for obtaining economically viable processes. In this work, a low-cost vegetable peroxidase extraction process is proposed; the resulting enzyme is characterized to determine its optimum pH, temperature, and stability conditions, and it is then applied in the decolorization of reactive dye Remazol Turquoise G 133%. The turnip peroxidase (TP) was utilized as an enzymatic source. This enzyme exhibited maximum activity at pH 7.0, and it was active in the temperature range of 30 to 50 °C, which favors its use in industrial processes. Acetone was the most efficient solvent to induce precipitation. The removal of Remazol Turquoise G 133% was 56.0% complete after 50 min, while 41.0% of the same dye was removed with the commercial horseradish peroxidase enzyme in 50 min. TP presents potential as a viable alternative in the decolorization of textile wastewaters.     

Decolorization and mineralization of reactive dyes by a photocatalytic process using ZnO and UV radiation

Reactive dyes are one of the major pollutants in textile wastewater and a concern because they are not easily degraded by conventional wastewater treatments. Heterogeneous photocatalysis has been considered an effective option for treating wastewater containing those dyes. This research work assesses the photocatalytic degradation of reactive dyes using UV irradiation and pure or impregnated ZnO. In addition to photocatalysis, separate photolysis and adsorption experiments were conducted but showed low efficiency. The dye degradation was monitored by UV-Vis spectroscopy and mineralization was determined by total organic carbon (TOC) analyses. Total color removal was achieved after 30 min of irradiation using pure ZnO. The Black 5 dye photocatalytic decolorization reaction followed first-order kinetics, while Yellow 145, Red 4 and Blue 21 dyes followed zero-order kinetics. TOC removals in the range of 70-80% were achieved after 240 min of individual photocatalytic treatment with ZnO. The performance of each photocatalyst was also compared when the four dyes were mixed together and the order of efficiency in the mineralization process was as follows: Fe/ZnO > ZnO > Co/ZnO. This result was explained by the crystal field theory.     

Use of submerged anaerobic membrane bioreactor (SAMBR) containing powdered activated carbon (PAC) for the treatment of textile effluents

This work investigated the use of submerged anaerobic membrane bioreactors (SAMBRs) in the presence and absence of powdered activated carbon (PAC) for the treatment of genuine textile wastewater. The reactors were operated at 35 °C with an HRT of 24 h and the textile effluent was diluted (1:10) with nutrient solution containing yeast extract as the source of the redox mediation riboflavin. The results showed that although both SAMBRs exhibited an excellent performance, the presence of PAC inside SAMBR-1 enhanced reactor stability and removal efficiency of chemical oxygen demand (COD), volatile fatty acids (VFA), turbidity and color. The median removal efficiencies of COD and color in SAMBR-1 were, 90 and 94% respectively; whereas for SAMBR-2 (without PAC) these values were 79 and 86%, In addition, the median values of turbidity and VFA were 8 NTU and 8 mg/L for SAMBR-1 and 14 NTU and 26 mg/L for SAMBR-2, indicating that the presence of PAC inside SAMBR-1 led to the production of an anaerobic effluent of high quality regarding such parameters.     

Biosorption of chromium(VI), nickel(II) and Remazol blue by Rhodotorula muciloginosa biomass

The passive removal of commonly used reactive dye and two heavy metals, from aqueous solutions by inexpensive biomaterial, yeast Rhodotorula muciloginosa biomass, termed biosorption, was studied with respect to pH, initial dye concentration and initial metal ion concentration. The biomass exhibited maximum dye and chromium(VI) uptake at pH 5 and pH 6 for nickel(II) in media containing 50 mg/L heavy metal and 50 mg/L remazol blue. It was found that the highest chromium(VI) removal yields measured were 31.3% for 49.0 mg/l initial chromium(VI) concentrations. The nickel(II) removal yield was 32.5% for 22.3 mg/L. Higher R. Blue removal yields were obtained, such as 77.1% for 117.5 mg/L. The maximum dye biosorption yield was investigated in medium with a constant dye (approximately 50 mg/L) and increasing heavy metal concentration. In the medium with 48.8, 103.8 and 151.8 mg/L chromium(VI) and constant dye concentration, the maximum chromium(VI) biosorption was 7.4, 9.3 and 17.1%, whereas the maximum dye biosorption was 61.6, 56.6 and 55.9%. The maximum nickel(II) biosorptions in the medium with dye were 38.1, 22.1 and 8.8% at 23.7, 37.7 and 60.1 mg/L nickel(II) concentrations. In these media, dye biosorptions were 93.9, 86.4 and 93.3%, respectively.     

Application of a sequential batch reactor system for textile dyes degradation: comparison between azo and phthalocyanine dyes.

Photocatalysis on supported TiO2 was combined with aerobic biological treatment in a sequential batch reactor to compare the degradation of two textile dyes: a blue azo dye (DR KBL CDG) and a green phthalocyanine dye (DR K4GN). Three reactors were run in parallel. SBR1 was used as a reference and was fed with urban wastewater only. SBR2 and SBR3 were fed with the same urban wastewater combined with pretreated (for SBR2) and non-pretreated (for SBR3) dye solution. For an azo dye concentration of 12 mg/L decolouration yields of 78 and 27% were achieved, respectively, in SBR2 and SBR3. For the phthalocyanine dye, the decolouration yields decreased to 24 and 15%, respectively. Concerning COD removal it decreases for both dyes with and without pretreatment, when the dye concentration increases. Although a detrimental effect on biomass could be observed, bacteria were able to cope with the inhibitory effect of the dyes.     

Layered double hydroxide (LDH)-coated attapulgite for phosphate removal from aqueous solution

In this study, a composite adsorbent, layered double hydroxide (LDH)-coated attapulgite (LDH-AP), was synthesized and characterized. Its potential application for LDH stabilizer and phosphate (P) removal from aqueous solution was evaluated using the batch mode and continuous mode in a packed bed column. The batch experiments revealed that the data of P adsorption onto LDH-AP could be well described by the Freundlich equation, and the maximum adsorption capacity was estimated to be 6.9 mg/g. The column experiments were conducted in the tap water and the results indicated that the competing anions could slightly decrease phosphate removal. The saturated column was regenerated by 0.2 mol/L of NaOH and the regenerated column was examined for its reuse in phosphate removal. The results of this study suggested that attapulgite could be used as an applicable stabilizer of LDH and LDH-AP could be potentially used as a promising filtration medium for phosphate removal.     

一体化超滤-膜混凝吸附生物反应器饮用水除污染效能

为了提高超滤-膜生物反应器(UF-MBR)的饮用水除污染效果,在其反应器中直接投加粉末活性炭进行吸附和聚氯化铝进行混凝,构建一体化超滤-膜混凝吸附生物反应器(UF-MCABR)。试验结果表明,在投药量为粉末活性炭8mg/L、聚氯化铝10mg/L时,UF-MCABR对TOC和CODMn的去除率比UF-MBR分别提高了37.1个百分点和29.8个百分点;对DOC和UV254的去除率分别提高了40.6个百分点和61.4个百分点,并取得了几乎100%的硝化效率和PO34-—P去除效率。UF-MCABR的膜污染速率较之UF-MBR显著降低。