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1.
In this study, untreated and treated wood fly ash (WA) was used as a low‐cost sorbent in batch sorption tests to investigate the removal of organic pollutants from a real wastewater generated by cleaning/washing of machinery in a wood‐laminate floor industry in Sweden. The experiments focused on the effect of the WA dosage and particle size on the removal efficiency for organic compounds. With a WA dosage of 160 g L?1 and a particle size less than 1 mm, the reductions of chemical oxygen demand (COD), biologic oxygen demand, and total organic carbon were 37 ± 0.4, 24 ± 0.4, and 30 ± 0.3%, respectively. Pre‐treatment of WA with hot water improved the COD removal efficiency by absorption from 37 ± 0.4 to 42 ± 1.6% when the same dosage (160 g L?1) was applied. Sorption isotherm and sorption kinetics for COD using untreated WA can be explained by Freundlich isotherm and pseudo‐second‐order kinetic models. Intra‐particle diffusion model indicates that pore diffusion is not the rate‐limiting step for COD removal. Based on the experimental data, WA could be used as an alternative low‐cost sorption media/filter for removal of organic compounds from real industrial wastewater.  相似文献   

2.
Olive mill wastewaters (OMWs), which are known to have deep impacts on the receiving water bodies due to their high‐strength contents of organic materials and color, must be treated before discharge. For this reason; a number of research studies have been available in current literature related to the treatment of OMWs. However, no widely accepted treatment alternatives have been proposed yet. The common results of these studies suggest that OMWs must be pretreated prior to final purification processes. This study focuses on the comparison of alternative pre‐treatment processes in the aspect of chemical oxygen demand (COD) removal and costs of operation. Centrifuging, lime precipitation, acid cracking, and electrocoagulation processes were performed to compare removal efficiencies and operational costs. The COD removal efficiencies for centrifuging, lime precipitation, acid cracking, and electrocoagulation processes were determined to be 30.1, 24.1, 20.0, 53.7%, respectively, with operational costs being $0.30, $0.37, $1.42, and $11.60 per cubic meter of wastewater treated, respectively. The centrifuging process was concluded to be the most appropriate one according to the COD removal efficiency and cost of operation.  相似文献   

3.
In the present study, the effects of initial COD (chemical oxygen demand), initial pH, Fe2+/H2O2 molar ratio and UV contact time on COD removal from medium density fiberboard (MDF) wastewater using photo‐assisted Fenton oxidation treatment were investigated. In order to optimize the removal efficiency, batch operations were carried out. The influence of the aforementioned parameters on COD removal efficiency was studied using response surface methodology (RSM). The optimal conditions for maximum COD removal efficiency from MDF wastewater under experimental conditions were obtained at initial COD of 4000 mg/L, Fe2+/H2O2 molar ratio of 0.11, initial solution pH of 6.5 and UV contact time of 70 min. The obtained results for maximum COD removal efficiency of 96% revealed that photo‐assisted Fenton oxidation is very effective for treating MDF wastewater.  相似文献   

4.
Major challenges attributed to dysfunctional wastewater treatment facilities in developing countries include lack of commitment and poor informed decision making by the higher municipal administration. This paper presents how process monitoring and control during full scale operation ensures sustainability of civic infrastructures like Al‐Bireh wastewater treatment plant (AWWTP). It is written from the perspective of practical process selection to evaluate the performance of AWWTP, a single‐sludge nitrification–denitrification process with aerobic sludge stabilization. Process monitoring data (July 2000–April 2007) from available monthly operating reports were analyzed and evaluated. Additional data on microbiological analysis and information about facility unit operations were gathered through review of published local literature and interviews with AWWTP personnel. Influent and effluent data evaluated were the chemical oxygen demand (COD), biological oxygen demand (BOD), total nitrogen (TN), and total phosphorus (TP). Despite annual and seasonal variations in AWWTP influent for COD, BOD, TN, and TP, the Palestinian wastewater reuse requirements for restricted irrigation were met. Process design and proper facility operation have direct impacts on effluent quality. The study concludes that regardless of the design capacity and process type, adequate administrative and operational management dictate the sustainability of AWWTP and reuse schemes.  相似文献   

5.
Slaughterhouse wastewater is one of the main sources of environmental pollutants, containing a high amount of organic matter (chemical oxygen demand (COD), biochemical oxygen demand (BOD)), total nitrogen (TN), total suspended solids (TSS), total phosphorus (TP), grease, and oil. The main aim of the present research is optimizing the coagulation–flocculation process and examining the effects of experimental factors with each other, for example, pH, the concentration of two different coagulants (FeCl3 and alum), rapid mixing rate, and settling time. Therefore, it is aimed to treat slaughterhouse wastewater using the coagulation–flocculation process with the optimization of the response surface methodology (RSM). COD, turbidity, and suspended solids (SS) of the treated wastewater are chosen as the response variables. Furthermore, the optimal conditions for three responses are acquired by employing the desirability function approach. When the experimental results of two coagulants are compared, it is observed that the alum coagulant gave better results for the three responses. The alum coagulant utilized in the present research is able to increase COD, SS, and turbidity removal efficiency by 75.25%, 90.16%, and 91.18%, respectively. It is possible to optimize coagulation–flocculation by utilizing the RSM analysis, which proves that coagulation can pre‐treat slaughterhouse wastewater.  相似文献   

6.
The purpose of the work was to verify and demonstrate, on a pilot plant scale, the applicability of the Slovak clinoptilolite as a natural selective ion exchanger for the removal of ammonia from tannery wastewaters. During the pilot treatment experiments at an industrial wastewater treatment plant of the Shoe Manufacturing Industry Svit-Otrokovice, about 260 m3 of wastewaters were treated. The regeneration process was carried out with 2% NaCl (pH = 9, NaOH) and the eluate was distributed into 3 fractions. Only the most concentrated ammonia fraction was stripped in the renovation step. The economic efficiency of the studied method was compared with the biological nitrification-denitrification method.  相似文献   

7.
This paper presents a field investigation of aromatic volatile organic compounds (AVOCs) emissions from a sequence batch reactor (SBR) with powdered activated carbon (PAC) to treat the wastewater in a large petroleum refinery plant. AVOC with high Henry's constant preferred to transfer from liquid‐phase into air‐phase so that might cause the emission and odor problem. During SBR operation, AVOC concentrations and distributions in wastewater, sludge and off‐gas were analyzed. The total AVOC removal from wastewater was >99% under the kinetic parameters of SBR operated. Batch experiments were carried out in the laboratory to obtain the adsorptive characteristic of AVOC onto PAC, but the results showed that bio‐degradation was the main removal mechanism (85%). Nevertheless, off‐gas emission (<1%) and AVOC in the sludge (<0.1%) remained a stable level. Oxidation/reduction potential (ORP) was correlated to the logarithm of the dissolved oxygen (DO) concentration in a linear relationship so that ORP profile could indirectly reflect the DO and biomass concentrations. Since the influent AVOC concentration was varied and difficultly to measure, ORP could be used as real‐time parameter for optimizing SBR operation. The results provided useful information for future evaluation of AVOC emissions from wastewater treatment plants.  相似文献   

8.
In this study, various amounts of oxygen were added to the anaerobic phase of an anaerobic‐aerobic sequencing batch reactor (SBR) receiving azo dye remazol brilliant violet 5R to mimic the input of oxygen into the anaerobic zones of biological textile wastewater treatment plants. The effect of oxygen on the anaerobic biodegradative capability of the mixed microbial culture for remazol brilliant violet 5R was investigated. To investigate the effect of oxygen on anaerobic azo dye biodegradation, the anaerobic phase of the SBR cultures were exposed to a very low limited amount of oxygen for various air flow rates. Initially, an air flow rate of 20 mL/min was applied, further on the air flow rate in the anaerobic phase was increased up to 40 mL/min. System performance was determined by monitoring chemical oxygen demand, color removal rate, activities of anaerobic (azo reductase) and aerobic enzymes (catechol 2,3‐dioxygenase, catechol 1,2‐dioxygenase). The results of percentage COD reduction at each stage were similar for all runs, giving an overall reduction of 96%. Anaerobic color removal efficiency and azo reductase activity of anaerobic microorganisms were adversely affected by the addition of oxygen. Color removal efficiencies of the anaerobic phases decreased from 80% down to 42 and 38% for the limited oxygen conditions of 20 mL/min and 40 mL/min, respectively. It was observed that the activity of catechol 2,3‐dioxygenase and catechol 1,2‐dioxygenase, involved in breakage of aromatic rings, increased after they are exposed to oxygen limited conditions compared to fully anaerobic conditions. It was also observed that catechol 1,2‐dioxygenase enzyme activity increased by increasing the oxygen level on oxygen limited conditions in the anaerobic zone.  相似文献   

9.
This study presents the influence of the addition of additives such as activated carbon, carbon tetra chloride, hydrogen peroxide, and potassium dichromate on ultrasonic reduction of pharmaceutical wastewater chemical oxygen demand (COD) under laboratory conditions. The addition of activated carbon increased the % COD reduction whereas the combined addition of activated carbon and H2O2/CCl4/K2Cr2O7 was found to show higher reduction. Among the various combinations investigated, the combined addition of activated carbon and CCl4 was found to be the best combination. However, the environmental and health problems associated with these chemicals limit the applicability of the process in an industrial level. Further investigation with this system showed that the initial pH and initial COD have significant influence on the removal rate. The data obtained were fitted with first order and Langmuir–Hinshelwood kinetic models. The values of the rate constants obtained indicated that the pharmaceutical wastewater can be treated efficiently by the proposed methods.  相似文献   

10.
Textile industry is one of the fastest growing industries and significantly contributes to the economic growth in Malaysia. However, this industry also has high water consumption and subsequently produces high discharge rate of wastewater with high load of contaminants. The release of dyes into the environment during textile fiber dyeing and finishing processes is a main source of water pollution. Individual wastewater treatment through physical, biological, or chemical method is often very costly and results in large amount of sludge. Thus, there is a need to look for alternative treatment processes that covers from pre to post wastewater treatment stage. This paper reviews the current scenario with respect to textile industry effluent in Malaysia and technologies available for the treatment of the effluent. Prospects, challenges, and recommendations for future direction as well as on‐going research works dedicated to the treatment of textile wastewater are also reviewed in detail.  相似文献   

11.
Oil refinery wastewater was treated using a coupled treatment process including electrocoagulation (EC) and a fixed film aerobic bioreactor. Different variables were tested to identify the best conditions using this procedure. After EC, the effluent was treated in an aerobic biofilter. EC was capable to remove over 88% of the overall chemical oxygen demand (COD) in the wastewater under the best working conditions (6.5 V, 0.1 M NaCl, 4 electrodes without initial pH adjustment) with total petroleum hydrocarbon (TPH) removal slightly higher than 80%. Aluminum release from the electrodes to the wastewater was found an important factor for the EC efficiency and closely related with several operational factors. Application of EC allowed to increase the biodegradability of the sample from 0.015, rated as non-biodegradable, up to 0.5 widely considered as biodegradable. The effluent was further treated using an aerobic biofilter inoculated with a bacterial consortium including gram positive and gram negative strains and tested for COD and TPH removal from the EC treated effluent during 30 days. Cell count showed the typical bacteria growth starting at day three and increasing up to a maximum after eight days. After day eight, cell growth showed a plateau which agreed with the highest decrease on contaminant concentration. Final TPHs concentration was found about 600 mgL−1 after 30 days whereas COD concentration after biological treatment was as low as 933 mgL−1. The coupled EC-aerobic biofilter was capable to remove up to 98% of the total TPH amount and over 95% of the COD load in the oil refinery wastewater.  相似文献   

12.
The pollution of underground and surface water streams is a tremendous environmental problem. Adsorption, in which activated carbon (AC) is used as an adsorbent, is one of efficient procedures to remove organic and inorganic pollutants from industrial wastewaters. Activated carbon fiber (ACF), a newly developed form of AC, has high adsorption rate and surface area and can be used for the treatment of industrial wastewaters. In this work, ACF was prepared by physicochemical activation method from kenaf and we studied its ability in the treatment of indigo‐containing wastewater produced from a dying factory. The filtered wastewater was treated via adsorption by ACF, and response surface experimental design method was used to study the effect of ACF dosage, contact time, temperature, and pH of the wastewater on the removal process. ACF dosage of 0.256 g, temperature of 12.5°C, pH 8.5, and contact time of 125 min were optimum treatment conditions. The adsorption process obeys pseudo‐second‐order kinetic and Freundlich isotherm models.  相似文献   

13.
Recycling the large amounts of organic wastes produced by agriculture, forestry, urban and industrial activities as soil, organic amendments are the most popular and efficient option for avoiding their dispersion in the environment and restoring, maintaining, and/or improving the content of soil organic matter. Chemical stability and biological maturity are two important factors for the successful use of organic wastes in agriculture with limited risk for the surrounding environment. Stabilization and maturation of raw organic wastes inherently imply the achievement of an extensive humification, that is, a wide conversion of easily degradable organic matter to refractory organic compounds that resemble native soil humic substances (HS). Soil HS are the most important components of soil organic matter responsible of several soil functions and processes. As a consequence, the amount and quality of HS‐like fractions in any organic amendment are believed to be of primary importance for its agronomic efficacy, environmental safety and economic value. The first part of this review focuses on the chemical and physico‐chemical changes occurring in the humic substances (HS) ‐like fractions of organic wastes of various nature and sources subjected to common treatment processes aimed at producing environmentally‐safe soil amendments with beneficial agronomic properties. The second part discusses the composition, structure, and chemical reactivity of the HS‐like components in organic amendments of various origins and nature, and their effects on native soil HS. The review concludes by highlighting the need for innovative research targeted mainly to achieve a better fundamental understanding of the molecular structure and reactivity of soil HS and HS‐like fractions in organic amendments, the mechanisms of HS formation and transformations in the natural environment and during the treatment processes of raw organic wastes, the interactions with metals and organic xenobiotics, and the direct physiological effects that HS may exert on plants.  相似文献   

14.
The gel-permeation chromatography system with multicomponent detection of organic carbon, organic nitrogen, organic halogen, and UV/vis absorption measurement is shown to be a useful tool for characterization of industrial wastewaters and wastewater treatment processes. The proposed system was used to investigate biologically treated wastewater from chemical industry, whereby one branch stream was identified to be the main source of persistent halogenated organics. Various treatment processes of pulp mill wastewater were also evaluated revealing that precipitation with aluminium is very effective for the removal of the high molecular fraction whereas the biological treatment is generally less selective. In the biological treatment of tannery wastewaters, it has been shown that the aerobic treatment, in contrast to anaerobic step, causes evident alterations of the composition of the polar DOC fraction. The nitrogen containing compounds are also better decomposed in the aerobic step compared to the anaerobic one.  相似文献   

15.
In this study, a new material consisting of activated‐carbon‐containing magnetic oxide is prepared for assisted microwave (MW) irradiation treatment of coking wastewater. The optimum condition for degrading coking wastewater is 98.14% chemical oxygen demand (COD), under which 87.57% ammonia nitrogen (NH3–N) can be removed. The results are verified by GC–MS, showing that most organic pollutants can be adsorbed by modified activated carbon (MAC). The surface morphology and elemental composition of MAC before and after microwave irradiation and adsorption is determined by scanning electron microscopy. After microwave irradiation, many apertures of pores looked relatively large. It can be shown that MAC as a catalyst in the microwave‐assisted treatment process has many advantages, including rapid degradation of COD and NH3–N. In conclusion, microwave‐irradiation‐assisted MAC treatment of coking wastewater is a novel technology that is economical, efficient, and has broad prospects for development.  相似文献   

16.
Feminization of fish has been reported throughout the world in freshwater and marine systems. While the population impacts are conflictive, enough negative effects warrant additional research into causation. In order to ascertain the identities of specific feminizing agents, variants of toxicity identification evaluations (TIEs) have been employed. The majority of these evaluations have utilized in vitro estrogen receptor-based cell-lines to identify chromatographic fractions that possess biological activity from predominately wastewater derived from municipal treatment facilities and have concluded that synthetic and natural estrogens are the primary cause for feminization of fish. This paper will focus on three aquatic systems impacted by wastewater originating from purely domestic, and industrial/domestic secondary treatment systems. Wastewater and sediment extracts were evaluated by in vitro and in vivo biological responses in a TIE fractionation design. While in vitro responses tended to mirror in vivo responses in purely domestic wastewater systems, in vitro responses tended to severely underestimate in vivo estrogenic activity when normalized to estradiol equivalents in more complex systems. TIE fractionation schemes using in vivo biological responses failed to indicate any relationship to steroids in either wastewater or sediment extractions. These data consistently support the view that mechanisms other than direct ER binding and activation by toxicants may be important in the feminization of fish particularly residing in habitats that receive complex wastewater or agricultural effluents.  相似文献   

17.
《Marine pollution bulletin》2009,58(6-12):250-254
Feminization of fish has been reported throughout the world in freshwater and marine systems. While the population impacts are conflictive, enough negative effects warrant additional research into causation. In order to ascertain the identities of specific feminizing agents, variants of toxicity identification evaluations (TIEs) have been employed. The majority of these evaluations have utilized in vitro estrogen receptor-based cell-lines to identify chromatographic fractions that possess biological activity from predominately wastewater derived from municipal treatment facilities and have concluded that synthetic and natural estrogens are the primary cause for feminization of fish. This paper will focus on three aquatic systems impacted by wastewater originating from purely domestic, and industrial/domestic secondary treatment systems. Wastewater and sediment extracts were evaluated by in vitro and in vivo biological responses in a TIE fractionation design. While in vitro responses tended to mirror in vivo responses in purely domestic wastewater systems, in vitro responses tended to severely underestimate in vivo estrogenic activity when normalized to estradiol equivalents in more complex systems. TIE fractionation schemes using in vivo biological responses failed to indicate any relationship to steroids in either wastewater or sediment extractions. These data consistently support the view that mechanisms other than direct ER binding and activation by toxicants may be important in the feminization of fish particularly residing in habitats that receive complex wastewater or agricultural effluents.  相似文献   

18.
Olive mills wastewater (OMW) is a critical environmental problem in the Mediterranean area due to its extremely high levels of COD and phenols. In this study, a group of adsorption experiments were conducted to investigate the dynamic response of the pH, COD, phenols, TSS, TDS, and TS concentrations of pretreated OMW, using different concentrations of activated carbon as adsorbent. The pretreatment included sedimentation and filtration of OMW. The pretreated OMW was then subjected to adsorption. A series of adsorption steps in stirred batch vessels were studied, namely, one stage, two‐stage countercurrent, and three‐stage countercurrent adsorption systems. A combined two‐ two‐stage countercurrent adsorption steps were also studied. Experimental results showed that such treatment protocols were promising. For example, a treatment protocol composed of a three‐stage countercurrent adsorption process using activated carbon of concentration of 24 g/L of OMW was able to reduce the COD from 60 000 mg/L down to 22 300 mg/L, while phenols were reduced from 450 to 15 mg/L.  相似文献   

19.
The physico‐chemical characteristics and microbial composition of the final effluents of two municipal wastewater treatment plants in South Africa were assessed between July and September 2009. The impact of the treated final effluents on the receiving water bodies was also evaluated. The temperature across all sampling points ranged between 14 and 22°C, while pH varied from 6.9 to 7.6. High levels of turbidity, chemical oxygen demand (COD), ammonia, nitrate, nitrite and orthophosphate (PO4) were observed in many cases. Turbidity of the samples was in the range of 2.2–288.6 NTU. The concentrations (mg/L) of other physico‐chemical parameters are as follows: COD (9.33–289); ammonia (0.000340–45.4); nitrate (0.062–539); nitrite (0.021–22.6); PO4 (5.3–33.2). The microbial quality of the effluents discharged from the plants did not comply with the limits set by the South African guidelines with respect to pathogens such as Salmonella, Shigella, Escherichia coli, total coliform, faecal coliform, enterococci, faecal streptococci, and viral particles for effluents intended for discharge into receiving watersheds. This study revealed an undesirable impact on the physico‐chemical and microbial qualities of the receiving water bodies as a result of the discharge of inadequately treated effluents from the wastewater treatment facilities. This poses a health risk to several rural communities which rely on the receiving water bodies primarily as their sources of domestic water and recreational purposes. There is therefore a need for the intervention of appropriate regulatory agencies in South Africa to ensure compliance of treatment facilities with wastewater effluent quality standards.  相似文献   

20.
Effectiveness of ultrasonication, microwave technologies, and enzyme addition prior to anaerobic digestion is investigated using sludge samples taken from the secondary settling tank of a domestic wastewater treatment plant to improve methane production, enhance dewaterability characteristics of the sludge, and to reduce excess sludge. Microwave pre‐treatment (1500 W, 10 min at 175 °C) results in better extra digester performance (compared to the control reactor) in terms of methane production (25 m3 ton?1 suspended solids (SS)) than ultrasound (no improvement) and enzyme pre‐treatment (11 m3 ton?1 SS). While methane production is not improved as a result of ultrasonication pre‐treatment (15 000 kJ kg?1 SS), a noticeable increase (19%) is observed in the case of microwave pre‐treatment. Higher compactibility values are obtained after ultrasonication and microwave application compared to the control (i.e., from 7.1 to 8.7 and 9.2%, respectively) before anaerobic digestion. Although ultrasonication and microwave application decrease the dewaterability of the raw sludge (capillary suction time (CST) from 827 to 1364 and 2290 s, respectively), similar dewaterability results are obtained at the end of the anaerobic digestion process for all pre‐treated sludge samples. An economic assessment of this study shows that pre‐treatment with microwave results in more than 10‐fold less net cost compared to the enzyme application.  相似文献   

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