Ozone Treatment of Sewage Works' Final Effluent

This paper describes a laboratory-based study which was designed to investigate (a) the changes in selected physico-chemical properties of a sewage-works' final effluent after ozonation, and (b) the effect of ozone on the concentration of organic halides and effluent toxicity and mutagenicity. Different conditions were studied involving the application of ozone concentrations up to 13.5% w/w and the ozonation of the effluent under both constant and variable ozonation rates.     

Direct and indirect photolysis of sulfamethoxazole and trimethoprim in wastewater treatment plant effluent

The photolysis of two antibacterial compounds, sulfamethoxazole and trimethoprim, was studied in wastewater effluent. The rate of loss of sulfamethoxazole was enhanced in wastewater effluent due to indirect photolysis reactions, specifically reactions with hydroxyl radicals and triplet excited state effluent organic matter. Photolysis in the presence of natural organic matter, however, did not lead to enhanced degradation of sulfamethoxazole. Trimethoprim was also found to be susceptible to indirect photolysis in wastewater effluents, with hydroxyl radical and triplet excited effluent organic matter being the responsible species. Deoxygenation of solutions led to more rapid direct photolysis of sulfamethoxazole and trimethoprim, indicating that direct photolysis proceeds through a triplet excited state, which was verified by demonstrating that trimethoprim is a singlet oxygen sensitizer. In the wastewater effluents tested, photolysis could be apportioned into direct photolysis (48% for sulfamethoxazole, 18% for trimethoprim), reaction with hydroxyl radicals (36% and 62%, respectively) and reaction with triplet excited effluent organic matter (16% and 20%, respectively). These results indicate that allowing photolysis in wastewater stabilization ponds or wastewater treatment wetlands may lead to enhanced pharmaceutical removal prior to discharge and that effluent organic matter has different photoreactivity than natural organic matter.     

Decolorization of dark brown colored coffee effluent by solar photo-Fenton reaction: effect of solar light dose on decolorization kinetics

The decolorization of dark brown colored coffee effluent by solar photo-Fenton process has been studied. Effects of accumulated solar light energy and dosage of Fenton reagents (iron and hydrogen peroxide) on the color removal have been examined. With increasing Fe dosage the rate of the decolorization increased but the enhancement was not pronounced beyond 10 mg L⁻¹. Although addition of H₂O₂ increased the decolorization rate up to around 1000 mg L⁻¹ of H₂O₂, further addition of H₂O₂ could not enhance the color removal. At excess dosages of Fenton reagents, the color removal was not improved due to their scavenging of hydroxyl radicals. It was found that the pseudo-first order decolorization kinetic constant based on the accumulated solar energy is a sole parameter unifying solar photo-Fenton decolorization processes under the different weather conditions. The kinetic constant can be readily used to calculate the amount of solar energy required to achieve a certain degree of color removal. The mineralization was rather slower as compared with the decolorization. The decolorization capability with solar irradiation was found to be comparable to UV light irradiation. The present results suggest that abundant solar energy driving decolorization of coffee effluent by photo-Fenton reaction is highly efficient.     

UV light assisted decolorization of dark brown colored coffee effluent by photo-Fenton reaction

The photochemical decolorization of coffee effluent has been examined by photo-Fenton (UV/Fe²⁺/H₂O₂) process. Effects of UV light intensity, initial coffee concentration, iron dose and H₂O₂ dose on the color removal of model coffee effluent have been investigated. The rate of decolorization increased with decreasing initial coffee effluent concentration. It was found that the Fe ion dose and UV light intensity enhanced the decolorization rate. The decolorization process of coffee effluent could be divided into three established phases. At the beginning of the photo-Fenton process, the instantaneous and significant increase in color of the solution was found (Phase-I). In the subsequent phase (Phase-II), the decolorization rate was initially fast and subsequently decreased. In Phase-III, the rate was accelerated and then the complete decolorization of model coffee effluent was achieved. In order to elucidate the mechanisms of coffee effluent color removal process, the concentration changes in Fe³⁺ and Fe²⁺ besides H₂O₂ were measured during the course of the photo-Fenton process. The rate-determining step in Phase-II was the photo-Fenton reaction or photoreduction of Fe³⁺. On the other hand, the decolorization process in Phase-III was highly affected by Fenton reaction or decomposition of H₂O₂ with Fe²⁺. About 93% mineralization of 250 mg L⁻¹ model coffee effluent was achieved after 250 min. A comparative study for TiO₂, ZnO and photo-Fenton oxidation processes has been also carried out and the photo-Fenton process was found to be the most effective for color removal of coffee effluent.     

Influence of molecular parameters on the sink effect in test chambers

The determination of the specific emission rates of individual products and materials under indoor-related conditions requires the use of climate-controlled emission test chambers. However, most chambers demonstrate an inherent sink effect, i.e. the released components undergo adsorption/desorption processes with construction materials. Furthermore, this sink effect is enhanced by introducing an adsorbing sample surface into the test chamber. The degree of adsorption, as well as the extent of the recovery, can vary significantly for different chambers and samples and also depends on the physical properties of the relevant substance. Whereas the sink effect caused by the chamber itself can be reduced by using appropriate construction materials, it is not possible to avoid the sink effect attributable to the actual sample. For this reason it is of importance to evaluate chambers and samples for possible sink effects, taking into consideration the physical properties of substances. This can be achieved by kinetic modeling of emission data and determination of rate constants. The kinetic parameters obtained from curve fitting were combined with molecular parameters and applied to multivariate statistics. The properties of three different chambers with and without sink could be compared by cluster analysis. Principal component analysis revealed that the sink effect essentially depends on the boiling point of the substances examined. PRACTICAL IMPLICATIONS: Emission test chambers are operated by research institutions and testing laboratories for different purposes. The determined emission rate value of a building product is a function of the chamber construction, the material to be tested and the molecular properties of the target compound. In this work it is demonstrated, which parameters have the main influence on the test result. Furthermore it is shown how multivariate statistical analysis can be applied to experimental data to characterize the sink effect under dynamic conditions. This new technique provides a suitable tool for the evaluation and comparison of test chambers.     

Combination of surfactant solubilization with permanganate oxidation for DNAPL remediation

A combination of surfactant solubilization with permanganate oxidation of trichloroethylene (TCE) was studied in batch, flow-through column, and three-dimensional (3-D) tank tests. Batch results showed that chloride production, an indication of TCE degradation, followed a pseudo-first-order reaction kinetics with respect to KMnO4 in the presence of free-phase TCE. A higher chloride production rate was achieved when anionic surfactants were present. The observed pseudo-first-order reaction rate constant increased as the concentrations of anionic surfactants Ninate 411 and Calfax increased from 0% to 0.1%, 0.3%, and 1.0%. Column experiments on TCE reduction by permanganate in the presence and absence of surfactants were carried out using well-sorted coarse Ottawa sand. The peak effluent TCE concentration reached 1700 mg/L due to enhanced solubilization when both sodium dodecyl sulfate (SDS) and permanganate were used, in contrast to less than 300 mg/L when only permanganate solution was used. In addition, the effluent TCE concentration decreased much faster when SDS was present in the permanganate solution, compared with the case when SDS was absent. With an initial 1 mL of TCE emplaced in the columns, the effluent TCE concentration dropped to <5mg/L after 29-31h of flushing with 1% SDS and 0.1% KMnO4 solution in contrast to 37-73 h when only 0.1% KMnO4 was used. Furthermore, KMnO4 breakthrough occurred after 21-25 h of injection when SDS was present compared with 45-70 h later when SDS was absent. A slightly higher chloride concentration was observed in the earlier stage of the column experiment and the chloride concentration decreased quickly once KMnO4 was seen in the effluent. The 3-D tank test showed that the MnO2 precipitation front formed more quickly when 1% SDS was present, which further confirmed the observation from the column study.     

Influence of dilution water on the toxicity of kraft pulp and paper mill effluent, including mechanisms of effect

Ten natural freshwater samples differing widely in pH and other characteristics were collected and examined for their influence as dilution waters on the acute lethality (24-h LC50 values) of a sample of bleached kraft whole mill effluent. When bioassays were conducted at the pH of each dilution water, LC50 values varied by 3.5-fold. These differences were largely accounted for by adjustment of the pH of each test solution to a common value (6.5). The remaining minor differences in LC50 values were attributed to the ionizable inorganic constituents of the dilution waters.A separate study examined the effects of test pH and the involvement of aging of solutions prior to bioassays or of pH overshoots during pH adjustment on the toxicity of a second sample of pulp mill effluent: using a single dilution water. The LC50 values obtained for bioassays conducted at pH 9.5 were significantly higher than those for tests performed at pH 6.5. Neither the adjustment of test solutions to pH 9.5 with immediate readjustment to pH 6.5, nor the prior aging of solutions at pH 9.5 or 6.5 with minimal or no aeration for 6 h, altered the differences due to test pH.The pH-toxicity relationship of the resin acid dehydroabietate and a third sample of bleached kraft whole mill effluent was similar throughout the pH range 5.0–10.5, with test solutions least toxic at pH 9.0–9.5. This pH-toxicity relationship for pulpmill effluents and the influence of dilution water pH on effluent toxicity were attributed mainly to the ionization equilibria of the effluents' resin acid constituents.     

The photocatalytic degradation of reactive black 5 using TiO2/UV in an annular photoreactor

The textile effluent is a major industrial polluter because it is highly colored, containing about 15% unfixed dyes as well as high levels of salts that can potentially be discharged into the environment. Photocatalytic oxidation using an thin gap annular UV reactor with TiO2 was used to break down the colour of a synthetic effluent ranging up to 400 ppm in dye concentration of Reactive Black 5 and up to 80 g/L in NaCl. Results show that the reaction kinetics was dominated by the TiO2 loading, the initial dye concentration, and the dissolved oxygen concentration; with the other parameters showing less significant effects. High rates of decolorization were found, with a linear fit to the Langmuir-Hinshelwood equation yielding a reaction rate constant (k) of 2.45 ppm/min, and an adsorption equilibrium constant (K) of 0.048 ppm(-1) based on color removal. The presence of the combination of high dissolved oxygen (15 ppm) and sodium chloride (up to 80 g/L) was found to enhance the decolorization and mineralization rates of the reactive dye. However, pH was found to not significantly affect the degradation rate. Since textile effluent is strongly alkaline, this result is significant, as no solution neutralisation is required and direct treatment of the effluent is possible.     

A possible correlation between environmental chemicals and pigment cell neoplasia in fish

A croaker (Nibea mitsukurii) has a high incidence of the skin melanoma, chromatophoroma, in a Pacific coastal area in Japan. A sea catfish (Plotosus anguillaris) bearing skin melanosis is also found in the same area. For elucidation of a correlation between these pigment cell neoplasms of the skin and environmental contaminants, an epidemiological survey was conducted to determine the distribution and prevalence of tumor-bearing fish. Based upon observations of a high prevalence of skin neoplasms near the discharge point for kraft pulp mills, experiments were conducted to determine the neoplastic induction efficiency of the effluent on the croaker and sea catfish species. Isolation and identification of mutagens in effluent extracts were carried out using the Ames test, followed by mass spectral analysis of mutagenic fractions. The effluent induced a chromatophoroma on one croaker of the 100 tested, and it induced pigment cell hyperplasia on 70 to 100% of the sea catfish. These skin neoplasms were grossly similar to those observed in the field. Five chloroacetones were identified from the Ames-positive fractions of the effluent, and tetrachlorocyclopentene-1,3-dione and two alpha-dicarbonyl compounds were also detected as mutagens. The above experiments indicate that the mutagenic contaminants found in kraft mill effluent may play an important role in the induction of skin neoplastic disease in fish.     

化学发光法测定铜的进展

概述了以鲁米诺、邻菲啉等为主要化学发光试剂 ,广泛应用于各种物料中测定微量铜的化学发光分析方法的进展 .分别叙述了用于测定微量铜的不同化学发光体系 ,发光试剂浓度 ,试剂溶液加入的先后顺序 ,以及不同介质溶液的选择等对体系化学发光强度的影响 .试验了表面活性剂对微量铜在化学发光体系中的敏化作用 ,同时研究了微量铜在化学发光体系中存在的不同形态对化学发光信号强弱的影响 .并且对以鲁米诺、邻菲啉为化学发光试剂在化学发光体系中的化学发光反应的机理进行了初步探讨     

A reliable monitoring of the biocompatibility of an effluent along an oxidative pre-treatment by sequential bioassays and chemical analyses

A new approach to assess biocompatibility of an effluent, based on combination of different bioassays and chemical analyses, has been tested using a mixture of four commercial pesticides treated by a solar photo-Fenton as target effluent. A very fast elimination of the pesticides occurred (all of them were below detection limit at t_30W = 36 min), but mineralisation was a more time-consuming process, due to the formation of organic intermediates and to the presence of solvents, as shown by GC-MS analysis. Measurements based on activated sludge indicated that detoxification was coincident with the removal of the active ingredients, while more sensitive Vibrio fischeri bacterium showed significant toxicity until the end of the experiment, although the effluent might be compatible with biological processes. Biodegradability of the solutions was enhanced by the photochemical process, to reach BOD₅/COD ratios above 0.8. Longer time bioassays, such as the Zahn-Wellens' test, support the applicability of coupling photochemical with activated sludge-based biological processes to deal with these effluents.     

Automatic sampling equipment and bod test nitrification

The influence of automatic sampling equipment on BOD test nitrification in non-nitrified final effluent was evaluated. Samples were tested for BOD, carbonaceous BOD, nitrogenous oxygen demand and concentration of nitrifying bacteria. Biofilms inside the equipment were tested for nitrification potential. A sampler utilizing continuous circulation of final effluent was found to support attached growth of nitrifying bacteria and was associated with relatively high effluent nitrogenous oxygen demand. The effluent nitrogenous oxygen demand and nitrification potential of attached growth were significantly less with a unit that aspirated effluent on an intermittent basis, purging the sample line with air before and after sampling. Peak nitrifier counts in samples from the continuous flow equipment exceeded those in samples from the intermittent flow equipment.     

绝热用玻璃棉及其制品甲醛释放量1立方米气候箱法检出限评定

绝热用玻璃棉及其制品由于其制造工艺,易造成甲醛的少量残留,而在使用1立方米气候箱法检测甲醛释放量的过程中,由于甲醛含量低,造成检测结果较真实情况偏低,甚至未检出,影响了检测的准确性。本文根据实验室条件、环境、实验用水、相关药品与试剂及仪器设备,计算1立方米气候箱法测定绝热用玻璃棉及其制品甲醛释放量的检出限,以期对检测工作有所帮助。     

Assessment of ammonia toxicity in tests with the microalga,Nephroselmis pyriformis,Chlorophyta

Previous studies of an industrial effluent have indicated toxic effects by the ammonium/water system in tests with the unicellular green alga, Nephroselmis pyriformis. This investigation was undertaken to determine the toxicity of ammonia to this alga, and to identify the dominant toxicant in an industrial process effluent. The algal standard test was modified to improve the pH control, i.e. by testing at shorter exposure time and in the presence of a buffering agent, 3 mM HEPES. Ammonia was found to be the predominant toxic form in the dissociating ammonium/water system and the specific toxicity of ammonia (EC50, 24 h exposure) was 2.34 microM (32.8 microg ammonia nitrogen/L). Due to the dissociation, the toxicity is strongly pH dependent. Joint toxicity with additive effects of ammonia and ammonium ions was indicated, but the toxicity of ammonium ions was almost a factor 100 less (EC50, 24 h exposure, 224 microM or 3140 microg ammonium-nitrogen/L). According to the results the EC50 for effect on growth rate of N. pyriformis in seawater of pH 8.0 is 71 microM total ammonium. Hence, this alga appears to be more sensitive to ammonia than other studied marine plankton algae. Ammonia was found to be the dominant toxicant in the industrial effluent, using N. pyriformis as test organism.     

Occurrence of antibiotics in hospital, residential, and dairy effluent, municipal wastewater, and the Rio Grande in New Mexico

This study had three objectives: 1) determine occurrence of antibiotics in effluent from hospitals, residential facilities, and dairies, and in municipal wastewater 2) determine antibiotic removal at a large wastewater treatment plant (WWTP) in Albuquerque, NM, and 3) determine concentrations of antibiotics in the Rio Grande, which receives wastewater from the Albuquerque WWTP. Twenty-three samples of wastewater and 3 samples of Rio Grande water were analyzed for the presence of 11 antibiotics. Fifty-eight percent of samples had at least one antibiotic present while 25% had three or more. Hospital effluent had detections of sulfamethoxazole, trimethoprim, ciprofloxacin, ofloxacin, lincomycin, and penicillin G, with 4 of 5 hospital samples having at least one antibiotic detected and 3 having four or more. At the residential sampling sites, ofloxacin was found in effluent from assisted living and retirement facilities, while the student dormitory had no detects. Only lincomycin was detected in dairy effluent (in 2 of 8 samples, at 700 and 6600 ng/L). Municipal wastewater had detections of sulfamethoxazole, trimethoprim, ciprofloxacin, and ofloxacin, with 4 of 6 samples having at least one antibiotic present and 3 having 3 or more. The relatively high concentrations (up to 35,500 ng/L) of ofloxacin found in hospital and residential effluent may be of concern due to potential genotoxic effects and development of antibiotic resistance. At the Albuquerque WWTP, both raw wastewater and treated effluent had detections of sulfamethoxazole, trimethoprim, and ofloxacin, at concentrations ranging from 110 to 470 ng/L. However, concentrations in treated effluent were reduced by 20% to 77%. No antibiotics were detected in the Rio Grande upstream of the Albuquerque WWTP discharge, and only one antibiotic, sulfamethoxazole, was detected in the Rio Grande (300 ng/L) below the WWTP.     

Selective removal of resin and fatty acids from mechanical pulp effluents by ozone

Fresh chemithermomechanical (CTMP) mill primary clarifier (combined) effluents were treated using a system capable of accurately applying small measured charges of ozone. It was shown that the efficiency of ozone transfer into effluent was much better than into water, and that there was no residual dissolved ozone. Small ozone charges destroyed high proportions of the total resin and fatty acids (RFAs) and juvabiones (JBs) present in the effluents. This effect diminished with increasing ozone charges. Likewise, effluent toxicity, as measured in the Microtox assay, decreased rapidly with the low ozone charges. The low charges of ozone were also shown to be effective in destroying both soluble and particulate RFAs. It was shown that there was a strong positive correlation between the RFA content and the acute toxicity of an effluent sample, and that all the acute toxicity was extractable with methyl-t-butyl ether. Both Microtox and Daphnia magna acute toxicity assays correlated with effluent RFA content, but the Microtox was somewhat more sensitive. Thus, ozone may be a useful economical treatment agent for selectively removing RFAs and toxicity from mill effluent streams.     

Mineralisation of coloured aqueous solutions by ozonation in the presence of activated carbon

The degradation of organic matter in coloured solutions of different classes of dyes by ozonation in the presence of activated carbon is investigated. The kinetics of the decolourisation and mineralisation of three different dyes solutions (CI Acid Blue 113, CI Reactive Red 241 and CI Basic Red 14) were studied in a laboratory scale reactor by three different processes: adsorption on activated carbon, oxidation with ozone and ozonation in the presence of activated carbon. The mineralisation of the solutions was followed by measuring the total organic carbon (TOC). Under the experimental conditions used in this work, activated carbon was not capable of completely removing the colour of the solutions in reasonable time. On the other hand, ozonation quickly decolourised all the solutions, but satisfactory removal of TOC was never achieved by this process. The combination of activated carbon with ozone enhanced the decolourisation of the solutions and especially the mineralisation of the organic matter. Activated carbon acts both as an adsorbent and as a catalyst in the reaction of ozonation. The surface chemistry of the activated carbon is an important parameter; it was observed that basic samples improve TOC removal. The main conclusions of this work were validated by treating a real textile effluent collected after the conventional biological treatment.     

基于人工神经网络的反硝化滤池外碳源投加控制

针对反硝化滤池外碳源过量投加导致的出水总碳超标与碳源浪费问题,利用实际污水与小试装置研究了最适外碳源投加量的影响因素,并应用人工神经网络建立了外碳源投加模型与脱氮效果预测模型。结果表明,基于进水总氮负荷与碳氮生化反应计量守恒而进行的外碳源投加可缓解碳源浪费与污染问题,但脱氮效果缺乏稳定性,可考虑通过进水ORP、p H值、DO与温度的综合影响来进行改进。应用自适应学习速率动量梯度下降法建立了输入为5项进水指标、输出为最适投加量的外碳源投加模型,相关系数为0.9648,表明模型中进水参数与最适投加量具有很好的相关性,外碳源投加模型的改进具有可行性。应用贝叶斯正则化法建立了输入为5项进水指标、输出为NO3^--N与NO2^--N浓度的脱氮效果预测模型,相关系数为0.9085,表明预测反硝化滤池的脱氮效果具有一定可行性。外碳源投加模型可配合脱氮效果预测模型构建反硝化滤池外碳源投加控制系统,完善污水厂的自动化控制。     

Photosonochemical degradation of phenol in water

The combination of ultrasound (US) and photochemistry has been used to degrade an aqueous solution of phenol. It was considerably more effective than ultrasound or ultraviolet (UV) light alone. Based on the results of total organic carbon (TOC) removal, it was shown that the synergistic action of ultrasound and ultraviolet light existed. Identification of the first intermediates of the reaction (hydroquinone, catechol, benzoquinone and resorcin) indicates that OH radicals are involved in the photosonochemical degradation mechanisms. The effects of parameters such as pH, saturating gases, and Fe2+ on the photosonochemical degradation have been studied. The experimental results have shown that lower pH and higher concentration of dissolved oxygen favor the phenol degradation and that the presence of Fe2+ enhanced TOC removal of phenol solutions.     

Responses of Hexaplex (Murex) trunculus to selected pollutants

We report the results of a recent survey of the concentration of natural estrogens (17beta-estradiol, 17alpha-estradiol, estrone, estriol) and the synthetic estrogen, 17alpha-ethynylestradiol in representative animal wastes and sewage treatment plant (STP) effluents in the Waikato region of New Zealand. Dairy farm effluent samples showed high levels of estradiol (19-1360 ng/L) and its breakdown product estrone (41-3123 ng/L) compared with piggery or goat farm effluents. The combined load for these estrogens (excluding beta epimer) varied from 60 to >4000 ng/L. The piggery effluent provided the lowest total estrogen load (46 ng/L), with estrone accounting for nearly 60% of the measured estrogens in this sample. The synthetic analogue, 17alpha-ethynylestradiol was detected only in one wastewater treatment plant sample, albeit at trace level. An estrogen receptor competitive binding assay was used to test the biological activity of the samples and confirmed that most agricultural waste samples contain high levels of estrogenic compounds. The potential of these wastes to cause endocrine disruption in the receiving ecosystem is unknown at present.