Removal Efficiency Of CODCr Research Articles

Degradation of polyvinyl-alcohol wastewater by Fenton’s reagent: Condition optimization and enhanced biodegradability

The pretreatment of refractory polyvinyl-alcohol (PVA) wastewater with low value of CODCr by Fenton’s reagent was investigated to enhance the biodegradability. The effects of operating conditions such as pH of the solution, Fe2+ dosage, H2O2 dosage, reaction time and initial PVA concentration on the removal efficiency of CODCr were discussed. It is demonstrated that the optimum value of pH for removal of CODCr is 5 and the most suitable dosages of H2O2 (2%) and FeSO4 (10 mg/L) are 5% and 8.0%, respectively. When the initial CODCr value of the PVA water is 760 mg/L, the favorable reaction time is 110 min. Under these optimum conditions, the removal ratio of CODCr is 58.6%–61.4%, and the value of biodegradability (CODB/CODCr) increases markedly from 8.9%–9.7% to 62.6%–68.3%.

Pilot Studies on Cloth Media Filter Applied in WWTP for the Treatment of Secondary Effluent

Cloth media filter was applied in the treatment of the effluent of a municipal wastewater plant through pilot scale test for water reuse. Ferric chloride (FeCl3), PAFC and polyaluminum chloride (PAC) were employed as coagulants respectively to carry out the test. The average removal efficiency of TP and CODCr was 28.76% and 8% after cloth media filter without coagulation, and TP removal was influenced by the influent water quality. However, precoagulation with coagulants of ferric chloride, PAFC, PAC, the average removal efficiency of TP was 63.58%, 60.13%, 66.94% respectively, and no influence of TP removal can be found by the influent water quality. The average removal efficiency of CODCr was increased to 17.7%、26.3% and 27.7%，SS was 70.7%、64.3% and 49.1%. TN and NH3-N were removed unstably after cloth media filter.

Study on Denitrification and Phosphorus Removal Using an Integrated A/O Trickling Filter

Two columns were experimented to compare trickling filter with integrated A/O trickling filter (IA/OTT) in this study. Denitrification and phosphorus removal were limited in traditional trickling filter. By designing anoxic section, adding carbon source and recycling outflow, denitrification was enhanced in IA/OTT. Meanwhile, chemical-biological methods were used to improve the phosphorus removal. It was shown that removal efficiency of CODcr, NH3-N, TN and TP were ideal. Compared with the traditional trickling filter, especially, the removal efficiency of TN and TP were respectively about 35% and 50% higher.

Biological Contamination Control of Activated Carbon Filter

Activated carbon filter is often used as the pretreatment process of nanofiltration or reverse osmosis membrane system, especially when the content of organics and free chlorine in influent water is high. However, a lot of microorganisms often rapidly reproduce in the activated carbon filter after continuous operation, resulting in a large number of bacteria in the effluent. So when the activated carbon filter was used as pretreatment of membrane systems, membrane fouling caused by biological contamination often occurred. The objective of this paper was to discuss how to effectively control the activated carbon biological contamination. Three different control methods—water backwashing, hot alkali treatment and ultrasound treatment were compared. Results showed that ultrasound treatment was the most effective. A relatively high removal efficiency of biomass (above 90%) was obtained when 40 kHz ultrasound was applied at 90 W for 20 min. Bacterial count in the effluent can be decreased from 3.90×104CFU•mL-1 to 8.5×103CFU•mL-1. After 3 days of continuous operation, bacteria count increased from 8.5×103CFU•mL-1 to 4.06×104CFU•mL-1. After ultrasound treatment, the removal efficiency of CODCr increased from -386.3% to 73.8%.

Hyperhaline Municipal Wastewater Treatment of a Processing Zone through Pilot-Scale A/O MBR, Part I: Characteristics of Mixture Liquor and Organics Removal

An integrated anoxic/aerobic membrane bio-reactor (A/O MBR) was designed to treat hyperhaline municipal wastewater from a processing zone of Tianjin, China. The characteristics of mixture liquor in MBR and removal performance of CODCr were studied, and the contribution of membrane and microbes to organic pollutant removal was evaluated and discussed. The experimental results show that MLSS and MLVSS had similar fluctuation and the ratio of MLVSS/MLSS fluctuated at around 0.4. Settling characteristics of the sludge in aerobic zone was nice at the first more than one month operation and was deteriorated significantly after two-month operation. The relative low MLVSS/MLSS ratio was due to the accumulation of large quantity of inert substance and inorganic matters since only once sludge discharge in the four-month investigation period and relative high inorganic substance in influent. The deterioration of sludge settling was caused by the accumulation of the SMP and EPS from microbe and high value of MLSS, which cause an increase in the electrophoretic mobility and surface electronegativity of the sludge and non-filamentous bulking in the bio-reactor. The CODCr removal efficiency of the integrated A/O MBR system was 80%-95% during the four-month investigation period. Very good organic removal is mainly contributed to the microbial biodegradation. To ensure a high-quality and stable effluent water, the contribution of membrane interception to activated sludge and insoluble organic matters cannot be neglected, especially under an unsatisfied biodegradation.

Research on CBR+PFB to Treat Domestic Wastewater

The combined process which consisted of a four-stage contact baffled reactor followed by a five-stage plant filter bed was used to treat domestic wastewater. The start-up of the four-stage contact baffled reactor was investigated, and the efficiency of the combined technology treating domestic wastewater was studied. The results indicated that the four-stage contact baffled reactor which inoculated with anaerobic sludge could be started up in 52 d, and the proper hydraulic residence time was 24 h; when the four-stage contact baffled reactor was running stably, its average CODCr removal efficiency was 57.0%, and in the four-stage contact baffled reactor, the average CODCr removal efficiency of each stage was decreased gradually, which were 45.8%, 11.1%, 6.8% and 3.3%, respectively; when the influent CODCr was 276-370 mg/L, the effluent CODCr of the combined technology was 73.0-90.7 mg/L and the average CODCr removal efficiency of the combined technology was 75.0%.

Treatment of leachate from domestic landfills with three-stage physicochemical and biochemical technology

Because domestic landfill leachate concentrates complex organic pollutants, effective treatment of landfill leachate has gained increasing attention in recent years. In this paper, three-stage physicochemical and biochemical technology for treatment of domestic landfill leachate is presented. Based on an eight-month pilot operation, over 96% of the main pollutants, for example CODCr, BOD5, SS, NH4 +–N, coliform, and chrominance, can be removed, among which the removal efficiency of CODCr was 89.5, 8.6, and 1.7% in stages 1, 2, and 3, respectively, and the removal efficiency of BOD5 was 90.3, 8.3, and 1.4%. In the treatment, the biochemical process played a principal role on the removal of pollutants from the leachate. The treatment efficiency depends on how the syntheses of physicochemical, anaerobic, and hydrolytic procedures pave the way for biochemical treatment. Application of a combined efflux and mixed-flow aerator enhanced the removal efficiency during each procedure.

Characteristics of aquatic plant roots, soil microbes and agricultural non-point source pollutant mitigation in riparian buffer zones

An experiment was conducted on the characteristics of root morphology and vitality, and soil microbial community diversity of three typical aquatic plants to determine their mitigation efficiency of agricultural non-point source pollutants in riparian buffer zones. All the aquatic plants used have significantly differences in the characteristics of root morphology and vitality. Root vitality values of the aquatic plants are in the following order: Iris pseudacorus Acorus calamus Lythrum salicaria. Root vitality has a significant correlation with root tip number. The aquatic plants show significant rhizosphere effect, soil microbial biomass in rhizosphere is markedly higher than that in bulk soils. Furthermore, microbial community in rhizosphere soils of the riparian buffer zone has the composition sequence as: bacteria actinomycetes fungi. Soil microbial community diversity index is as follows: I. pseudacorus A. calamus L. salicaria, having the same tendency as that of root vitality. The order of removal efficiency of TN, TP and CODCr by the aquatic plants in the riparian buffer zone is I. pseudacorus A. calamus L. salicaria. The results suggest that variations in root vitality caused by differences in root structure of aquatic plants influence soil microbial community structure and diversity. This results in the differences in removal efficiencies of agricultural non-point source pollutants in riparian buffer zones.

Performance of a novel dynamic membrane bioreactor in treating synthetic domestic wastewater

This article introduced an approach using cross-linked polyvinyl alcohol microspheres (PVA-MS) to form dynamic membrane on the surface of the industry filter cloth instead of the conventional MF/UF membrane to build a membrane bioreactor (MBR) for wastewater treatment. The performance of the dynamic MBR for treating synthetic domestic wastewater and membrane fouling were investigated. For treating synthetic domestic wastewater sequentially, the results of the batch tests showed that the effluent turbidity was less than 4 NTU and SS was zero at the most operation time. The average removal efficiency of CODCr and NH4+-N were 93.18 and 98.6%, respectively. Membrane fouling was mainly caused by sludge layer. The sludge cake and precoated dynamic membrane could be easily removed by brushing. The support membrane permeate flux was almost recovered fully and could be reused again. These results indicated that the precoated dynamic membrane could prevent pollutants and biomass intervening to the surface and interior of the support membrane which was helpful to alleviate support membrane fouling. The experimental results demonstrated that the novel dynamic membrane showed highly anti-fouling characteristics in the MBR and could be a potential technology for wastewater treatment.

Performance of the NF-RDM (Rotary Disk Membrane) module for the treatment of landfill leachate

This study was to investigate the performance of NF-RDM (Rotary Disk Membrane) module for the treatment of landfill leachate with high organic concentration. In the various TS concentrations, the optimal rotating speed was around 400 rpm. In the volume reduction test to minimize the concentrate quantity, the flux decreased by 43.4% (17.9 to 10.1 L/m 2/h) during 20-fold volume reduction. The water qualities of permeate were suitable to drain away to river environment. The physical and chemical cleaning of fouled membrane could recover about 97% of the initial flux. High removal efficiency of COD cr, Color, T-P was obtained, but the removal rate of NH 4 +-N was very low being about 25%. Therefore, a RO process was adopted and 92% of NH 4 +-N was rejected by RO. NF-RDM system combined with a RO process appeared to be a suitable technology to treat landfill leachate without any biological and chemical treatments.

Reuse of printing and dyeing wastewater in processess assessed by pilot-scale test using combined biological process and sub-filter technology

In this work, a pilot-scale (300 m 3/d) wastewater reclamation system was tested for printing and dyeing wastewater treatment from a textile factory. The wastewater was first hydrolyzed under anoxic condition, and then was treated under aerobic condition. Biologically treated wastewater was filtered by sub-filter technology (Patent: CN1308024A). The results showed that the average concentration of CODcr, color and turbidity in the effluent were less than 50 mg/L, 10 times and 2 NTU, respectively. The average CODcr, color and turbidity removal efficiencies were 91%, 92.5% and 90.9%, respectively. The treated effluent quality satisfied the requirement of water quality for printing and dyeing process. The most attracting part of the work was its extremely low color, low turbidity, low concentration of Fe and Mn, which was always demanded in textile sectors for an improved finish and better quality dyeing.

Nitrogen removal performance and microbial community structure dynamics response to carbon nitrogen ratio in a compact suspended carrier biofilm reactor

A compact suspended carrier biofilm reactor (SCBR) was developed for simultaneous nitrification and denitrification (SND) in a single reactor and the performance of nutrient removal was investigated. Microbial community structure response to different ratio of carbon to nitrogen (C/N) was determined by denaturing gel gradient electrophoresis (DGGE) profiles of 16S rDNA V3 region and amoA gene amplifications. In addition, the population dynamics of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) were estimated by fluorescence in situ hybridization (FISH) with 16S rDNA-targeted oligonucleotide probes. Results showed that the compact SCBR was efficient in nutrient removal with COD Cr removal efficiency over 90% and SND efficiency ( E SND) about 83.3%. The diversity of microbial community structure was positively correlated with C/N ratio, while the three communities of amoA gene were relativity homogenous. The population of nitrifiers was in inverse proportions to C/N ratio with the average fraction of AOB and NOB to all bacteria 5.4, 4.8, 3.1% and 4.6, 3.5, 2.7% respectively as C/N ratio changing from 3:1, 5:1 to 10:1. Therefore we could reach a conclusion that the compact SCBR was practical to treat municipal wastewater and the shift of microbial community monitored by molecular technologies could offer guidance to the process optimization in engineering.

Treatment Performance of Photocatalysis/H<sub>2</sub>O<sub>2</sub>/Metal Membrane Process for Organics Removal

The objective of this study is to evaluate the performance of photocatalysis/hydrogen peroxide/metal membrane system. Metal membrane for the separation of TiO2 particles was used in an experiment and nominal pore size is 0.5 μm. Hydrogen peroxide was tested as oxidants. The removal efficiency of CODCr and color for initial hydrogen peroxide concentration increases rapidly with an increase in the hydrogen peroxide concentration up to 50 mg/L. The removal efficiency of of CODCr and color for 50 mg/L of initial hydrogen peroxide concentration was about 95 % and 98 %, respectively. However, the addition of hydrogen peroxide over 50 mg/L inhibits the system efficiency. The addition of hydrogen peroxide in UV/TiO2 system enhanced removal efficiency of CODCr and color compared to no addition of hydrogen peroxide. This may be ascribed to capture the electrons ejected from TiO2 and to produce OH radicals. The application of metal membrane in UV/ TiO2/H2O2 system enhanced removal efficiency of CODCr and color due to the adsorption of metal membrane surface as well as the production of OH radical. In application of metal membrane with nominal pore size 0.5 μm, TiO2 particles were effectively separated from the treated water by metal membrane rejection. Photocatalytic metal membrane was much smaller resistance than these of humic acid, TiO2 and humic acid/ TiO2 due to humic acid degradation of photocatalytic reaction.

Preparation of rare-earth metal complex oxide catalysts for catalytic wet air oxidation

Catalytic wet air oxidation (CWAO) is one of the most promising technologies for pollution abatement. Developing catalysts with high activity and stability is crucial for the application of the CWAO process. The Mn/Ce complex oxide catalysts for CWAO of high concentration phenol-containing wastewater were prepared by coprecipitation. The catalyst preparation conditions were optimized by using an orthogonal layout method and single-factor experimental analysis. The Mn/Ce serial catalysts were characterized by Brunauer-Emmett-Teller (BET) analysis and the metal cation leaching was measured by inductively coupled plasma torch-atomic emission spectrometry (ICP-AES). The results show that the catalysts have high catalytic activities even at a low temperature (80°C) and low oxygen partial pressure (0.5 MPa) in a batch reactor. The metallic ion leaching is comparatively low (Mn<6.577 mg/L and Ce<0.6910 mg/L, respectively) in the CWAO process. The phenol, CODCr, and TOC removal efficiencies in the solution exceed 98.5% using the optimal catalyst (named CSP). The new catalyst would have a promising application in CWAO treatment of high concentration organic wastewater.

Treating Sewage using Coimmobilized System of Chlorella pyrenoidosa and Activated Sludge

Chlorella pyrenoidosa was coimmobilized with activated sludge to produce algae-bacteria beads for sewage treatment. Hydrolysis/acidogenesis pretreatment could improve the symbiotic microenvironment of coimmobilized Chlorella pyrenoidosa and activated sludge, and as a result, promote the removal of nutrients (CODcr, inorganic nitrogen and inorganic phosphorus) in the sewage. A photo-bioreactor combining hydrolysis/acidogenesis pretreatment and coimmobilized technique was designed to treat sewage continuously. The results show that, the removal efficiencies of CODcr, NH4 +-N and TP reached steady state after 4-days of experiment. The removal efficiencies of CODcr, NH4 +-N and TP were 59.6%, 59.0% and 60.3% respectively.

Disinfection and oxidation of sewage effluent water using ozone and UV technologies

This study was aimed at exploring the reclamation of sewage treatment plant effluent water (SEW) as an alternative water resource. For the oxidation of SEW, an ozone-UV system, based on the results of the combined ozone/UV process performed in our previous study, was set up under practical conditions, including a series type, continuous mode, semi-pilot scale operation (1.5 m3/d). As a result, the serial contact of the ozone and UV reactors showed lower CODCr and TOC removal efficiencies. However, these were greatly enhanced by recycling the water flow of the ozone-UV system at 40Q, as a result of the improvements in the transferred ozone dose in the ozone reactor and the contact efficiency between photons and ozone in the UV reactor, which approached that achieved in the combined ozone/UV process. For the disinfection of SEW, carried out in a syringe-type batch reactor, the increase of instantaneous ozone demand (ozone ID) led to a higher inactivation efficiency, an increased UV transmittance due to ozonation, and an enhanced inactivation rate of E. coli in the UV reactor. Additionally, it was concluded that the ozone/UV process could overcome the limitations of the ozone alone and UV alone processes for the reclamation of sewage effluent water.

Low strength wastewater treatment under low temperature conditions by a novel sulfur redox action process

The objective of this research is to make a novel wastewater treatment process activated by a sulfur-redox cycle action of microbes in low temperature conditions. This action is carried out by sulfate-reducing bacteria (SRB) and sulfur-oxidizing bacteria (SOB). The process was comprised of a UASB reactor as pre-treatment and an aerobic downflow hanging sponge (DHS) reactor as post-treatment. As the results of reactor operation, the whole process achieved that over 90% of CODcr removal efficiency, less than 30 mgCODcr/L (less than 15 mgBOD/L) of final effluent, at 12 h of HRT and at 8 degrees C of UASB reactor temperature. Acetobacterium sp. was detected as the predominant species by PCR-DGGE method targeting 16SrDNA with band excision and sequence analysis. In the UASB reactor, various species of sulfate-reducing bacterium, Desulfobulbus sp., Desulfovibrio sp., and Desulfomicrobium sp., were found by cloning analysis. In the DHS reactor, Tetracoccus sp. presented as dominant. The proposed sulfur-redox action process was considered as an applicable process for low strength wastewater treatment in low temperature conditions.

Degradation of dye wastewater containing reactive brilliant blue X-BR using a rotating electrochemical disc process

Abstract Dyes are widely used in industrial activities. It is difficult to treat dye effluent because it is strongly colored and contains high Chemical Oxygen Demand (COD). In an effort to treat the dye effluent, we developed a new treatment method—Rotating Electrochemical Disc Process (RECDP). The influence of rotate speed, voltage, pH and treatment time on the removal efficiency of color and CODcr was investigated. The high removal efficiency for the simulated dye wastewater was obtained at the operating condition (rotate speed: 70 r/min, voltage: 10 V and pH: 7.02). Furthermore, the degradation mechanism was studied by UV-Vis spectrophotometry. * Supported by National Natural Science Foundation of China (Grant No. 20477206)

Treatment of refectory oily wastewater by electro-coagulation process

Electro-coagulation was used to treat refectory wastewater with high oil and grease contents. Different operational conditions were examined, including pH, current density, reaction time, conductivity, electrode distance and inlet concentration. The optimum current density was 10–14 A m −2 within 30 min depending on the wastewater properties tested. Conductivity had little effect on the treatment efficiency. Although the addition of extra salts (e.g., sodium chloride) to the wastewater did not help increase the pollutant removal efficiency, it could save the power consumption significantly. The COD Cr and oil removal efficiency descended with increasing electrode distance. The optimal electrode distance was determined to be 10 mm for this equipment in consideration of the treatment cost and efficiency together. The pH effect on the performance of the electro-coagulation process was not very significant in the range of 3–10. The removal efficiency of oil and COD Cr under normal condition exceeded 95% and 75%, respectively.

Treatment of chitin-producing wastewater by micro-electrolysis-contact oxidization.

The technique of micro-electrolysis-contact oxidization was exploited to treat chitin-producing wastewater. Results showed that Fe-C micro-electrolysis can remove about 30% COD(cr), raise pH from 0.7 to 5.5. The COD(cr) removal efficiency by biochemical process can be more than 80%. During a half year's operation, the whole system worked very stably and had good results, as proved by the fact that every quality indicator of effluent met the expected discharge standards; which means that chitin wastewater can be treated by the technique of micro-electrolysis, contact oxidization.