Average CODCr Research Articles

AnCMBR-AFB-integrated process for the treatment of high nitrogen and phosphorus wastewater.

Improving the nitrogen and phosphorus removal rates and efficiently controlling membrane fouling are the keys to fully exploiting the applicability of anaerobic membrane bioreactor (AnMBR) process in high-concentration wastewater treatment. To that purpose, an integrated reactor composed of an anaerobic ceramic membrane bioreactor and N anaerobic fluidized bed (AnCMBR-AFB) was built and pollutant removal efficiency, nitrogen and phosphorus recovery characteristics, and membrane pollution features of this integrated reactor were investigated. The results revealed that the integrated reactor had good pollutant removal efficiency, with turbidity, chromaticity, and UV254 average values of the effluent being 0.470 NTU, 0.011 A, and 0.057 cm-1, respectively, and the average CODCr removal rate was 80%. The nitrogen and phosphorus recoveries were significantly higher than the nitrogen and phosphorus removal rates of conventional AnMBR at 23.20 ± 1.17% and 43.34 ± 1.54%, respectively. Microscopic analysis revealed the formation of magnesium ammonium phosphate (MAP) crystals on the carrier's surface, and friction between the carrier and the membrane surface could delay membrane fouling while allowing the contaminated membrane surface to retain significant roughness. Membrane fouling was mostly brought on by amides and saturated hydrocarbons, and inorganic metal ions also played a role to some extent.

The Interaction Effects of Aeration and Plant on the Purification Performance of Horizontal Subsurface Flow Constructed Wetland.

Aeration and plants exhibit influence on the water purification performance in constructed wetlands (CWs). However, the interaction between aeration and plants on enhancing performance of domestic sewage treatment is unclear. Our study aims to optimize the combination of aeration position and plant species, promoting the extensive and effective application of CWs. Herein, six horizontal subsurface flow (HSSF) CWs small scale plots were established and divided into two groups according to the plant (i.e., Canna indica and Iris sibirica). To adjust the distribution of dissolved oxygen (DO) in CWs, each group had three plots of HSSF CWs. One plot was aerated at the bottom of the first quarter of the filtration chamber, one plot was aerated at the bottom of the inflow chamber, and the remaining plot was not aerated as a control. Results showed that aeration at the bottom of the first quarter filtration chamber could contribute to the highest removal efficiency of chemical oxygen demand (COD), ammonium nitrogen (NH4+-N) and total nitrogen (TN). The COD, NH4+-N, and TN removal percentages decreased with the drop in temperature. However, the plot aerated at the bottom of the first quarter filtration chamber with I. sibirica exhibited the best average CODCr, NH4+-N and TN removal percentages in both the warm season (83.6%, 82.7% and 76.8%) and the cool season (66.3%, 44.1% and 43.8%). Therefore, this study indicated that the combination of aerating at the bottom of the first quarter filtration chamber and planting with I. sibirica in the HSSF CWs would be a promising way forward for wastewater treatment, especially in low temperature seasons.

Experimental Study on Treatment of Dyeing Wastewater by Activated Carbon Adsorption, Coagulation and Fenton Oxidation

In this paper dyeing waste water was simulated by reactive brilliant blue XBR, activated carbon adsorption process, coagulation process and chemical oxidation process were used to treat dyeing waste water. In activated carbon adsorption process and coagulation process, the water absorbance values were measured. The CODcr value of water was determined in Fenton chemical oxidation process. Then, the decolorization rate and COD removal rate were calculated respectively. The results showed that the optimum conditions of activated carbon adsorption process were as follows: pH=2, the dosage of activated carbon was 1.2g/L, the adsorption reaction time was 60 min, and the average decolorization rate of the three parallel experiments was 85.30%. The optimum conditions of coagulation experiment were as follows: pH=8~9, PAC dosage was 70mg/L, stirring time was 20min, standing time was 45min, the average decolorization rate of the three parallel experiments was 74.48%. The optimum conditions for Fenton oxidation were Fe2+ 0.05g/L, H2O2 (30%) 14mL/L, pH=3, reaction time 40min. The average CODcr removal rate was 69.35% in three parallel experiments. It can be seen that in the three methods the activated carbon adsorption treatment of dyeing wastewater was the best one.

Synthesis of Magnetic Sonophotocatalyst and its Enhanced Biodegradability of Organophosphate Pesticide

A magnetic sonophotocatalyst Fe3O4@SiO2@TiO2 is synthesized for the enhanced biodegradability of organophosphate pesticide. The as-prepared catalysts were characterized using different techniques, such as Xray diffraction (XRD) and transmission electron microscopy (TEM). The radial sonophotocatalytic activity of Fe3O4@SiO2@TiO2 nanocomposite was investigated, in which commercial dichlorvos (DDVP) was chosen as an object. The degradation efficiency was evaluated in terms of chemical oxygen demand (COD) and enhancement of biodegradability. The effect of different factors, such as reaction time, pH, the added amount of catalyst on CODCr removal efficiency were investigated. The average CODCr removal efficiency reached 63.13% after 240 min in 12 L sonophotocatalytic reactor (catalyst 0.2 g L, pH 7.3). The synergistic effect occurs in the combined sonolysis and photocatalysis which is proved by the significant improvement in CODCr removal efficiency compared with that of solo photocatalysis. Under this experimental condition, the BOD5/ CODCr ratio rose from 0.131 to 0.411, showing a remarkable improvement in biodegradability. These results showed that sonophotocatalysis may be applied as pre-treatment of pesticide wastewater, and then for biological treatment. The synthesized magnetic nanocomposite had good photocatalytic performance and stability, as when it was used for the fifth time, the CODCr removal efficiency was still about 62.38%.

Refining wastewater treatment using EGSB-BAF system

The performance of an expanded granular sludge bed (EGSB) in combination with a biological aerated filter (BAF) system for petroleum refining wastewater treatment was investigated. The system was monitored for two months at a hydraulic retention time of 17.5 h and a digestion temperature of 34 ± 1°C. The results showed that the total chemical oxygen demand (CODCr) and oil removal efficiencies were up to 90 and 87%, respectively, with the average CODCr and oil concentrations of 85 and 11 mg/L in the system effluent. Moreover, almost 97% of suspended solids (SS) were removed by the system and the effluent SS concentration was only 15 mg/L. The sludge yield coefficient of 0.0036 mg/mgCODCr showed a low excessive sludge production for the EGSB reactor. The excellent treatment performance indicated that this EGSB-BAF system could be appropriate for refining wastewater treatment. Besides, methane yield was only about 0.21 mLCH4/mgCODCr in the EGSB reactor, lower than the theoretical yields. The poor methane production together with the low oil concentration and increased biodegradability of effluent indicated that the biochemical reaction of refining wastewater mainly remains in hydrolytic acidification phase in the EGSB reactor. For this reason, it was proposed that a highly efficient anaerobic process such as EGSB could be used as a pre-treatment process to improve the biodegradation performance of the following aerobic biochemical treatment.

Performance and bioparticle growth of anaerobic baffled reactor (ABR) fed with low-strength domestic sewage

We investigated the performance of a 15.3 L capacity anaerobic baffled reactor (ABR) toward the treatment of low-strength domestic wastewater. The startup period of the ABR was finished within approximately 130 days at a temperature below 25°C. The average CODCr in the effluent was 165 mg·L−1, and the corresponding CODCr removal efficiency of the ABR was 52.3%. During the third stage (from day 130 to day 233) of ABR operation, the average CODCr in the effluent reached 71 mg·L−1, which meets the secondary discharge requirement of the Integrated Wastewater Discharge Standard (GB 18918-2002, China). Moreover, partial microbial separation was observed along the five ABR compartments through scanning electron microscopic images. The geometric mean diameter of bioparticles in the five compartments increased from 0.050 mm to 0.111, 0.107, 0.104, 0.110, and 0.103 mm during the start-up stage. After operation for 179 days, the corresponding diameters further increased to 0.376, 0.225, 0.253, 0.239, and 0.288 mm, respectively. The fractal dimensions of the bioparticles indicated that these particles have smoother surfaces and more compact structures during ABR operation. Morphological analysis of the bioparticle sections demonstrated that the bioparticles have a pore volume of 30%–55%. The highest porosity was observed for the bioparticles in the second ABR compartment, whereas the lowest fractal dimension of bioparticle section was observed in the fifth compartment.

Removal of chemical oxygen demand and dissolved nutrients by a sunken lawn infiltration system during intermittent storm events

Urban surface water runoff typically contains high but varying amounts of organic matter and nutrients that require removal before reuse. Infiltration systems such as sunken lawns can improve water quality. However, there is currently insufficient information describing the treatment efficiency of lawn-based infiltration systems. In this study, novel sunken lawn infiltration systems (SLISs) were designed and their pollutant removal effectiveness was assessed. The results revealed that SLISs with Poa pratensis and Lolium perenne effectively removed most chemical oxygen demand (CODCr) and dissolved nutrients. Average CODCr, total nitrogen (TN), ammonium-nitrogen (NH4(+)-N) and total phosphorus (TP) concentrations were reduced by 78.93, 66.64, 71.86 and 75.83%, respectively, and the corresponding effluent concentrations met the standard for urban miscellaneous water consumption in China. The NH4(+)-N in the synthetic runoff was shown to be removed by adsorption during the stormwater dosing and nitrification during subsequent dry days, as well as through uptake by plants. Phosphorus was mainly removed by adsorption and chemical precipitation. The NH4(+)-N and phosphorus Langmuir isotherm model fitted the clay loam soil adsorption process better than the Freundlich model. Overall, these results indicate that an SLIS provides an alternative means of removing runoff pollutants owing to its efficiency, easy operation and maintenance.

표면개질 담체를 이용한 충전탑 반응기에서 유기물 제거 및 미생물 부착 특성

This study was accomplished using packed bed column reactors that contain nonsurface-modified polypropylene media and surface-modified media from hydrophobic surface property into hydrophilic property by ion beam irradiation. The objectives of this research was investigated the characteristics of organic compounds removal and microbe attachment from sewage of school cafeteria in these reactors. In 736.8 mg/L of the average inflow COD Cr concentration the reactors with and without surface modification showed 81.8% and 70.3% of average COD Cr removal efficiencies, respectively, which proves the COD Cr removal efficiency of surface-modified media reactor is higher than that of nonsurface-modified media reactor. After 90 days, there were maximum differences between modified system and nonmodified system. In that time the maximum removal efficiency of COD Cr was 96.5% in modified system and was 85.2% in non-modified system that showed removal efficiency of surface-modified media system is 11.3% higher than that of nonsurface-modified media system. The average removal efficiency of SS was 80.4% for the surface modified system and 61.6% for the non-modified system under same condition. Also, the reactor of surface-modified media has advantage on microbe attachment and biofilm formation.

Community Domestic Wastewater Treatment by UCT-HMBR Process

In order to treat community domestic wastewater, the UCT (the University of Cape Town) process coupled with the Hybrid Membrane Bioreactor (HMBR) was selected to constitute a combination process UCT-HMBR. This hybrid reactor was characterized by high total biomass and low membrane fouling. After 42 days’ running, a significant biofilm was formed in the reactor. Data collected during 60-day stable running period showed that the average CODCr and ammonia removal efficiency are 95.7% and 97.7%, respectively. When the nitrate liquid recycle ratio is 300% the total phosphorus (TP) removal reaches the peak and TP removal efficiency is 83.2%. At the same time, the effluent total nitrogen is less than 15mg/L. The effluent of the UCT-HMBR can meet the national water reuse standard.

Study on Advanced Treatment of Pulping and Papermaking Process Effluent by Immobilized Laccase

The lacasse was immobilized by sodium alginate for papermaking wastewater treatment. The influence of the important factors on the treatment effect was studied by single factor test; and the optimized condition of immobilized lacasse treating papermaking wastewater was investigated by orthogonal test. The result shows that the optimum conditions are pH4, reaction time is 24h, shaker rotation speed is 160r/min, and reaction temperature is 40°C. The decoloring rate reach 73.3%, the COD removing rate is more than67.2%, the average CODCr and chroma of the treated water respectively are 98.3mg/L and 45.4times, The quality of the final water not only can completely satisfies the new discharge standard, but also the recycle requirements.

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%.

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.

Full Scale UASB Reactor Performance in the Brewery Industry

In this paper the 7 year experience of the Oriental Breweries, located in Kumi, Korea utilizing a full-scale upflow anaerobic sludge blanket (UASB) reactor for the anaerobic pretreatment of brewery wastewater is presented. The anaerobic pretreatment system selected has successfully achieved the desired treatment efficiency for the brewery wastewater during that period and it has also continued operation even with low wastewater concentrations (average CODcr 1,400 mg l−1) and lower flow rates than specified by the design parameters. The CODcr removal of the UASB reactor averaged over 80% throughout the entire period, incurring normal running expenses of only $0.20∼0.31 m−3 of treated water. In addition a further economical feature of the process was the utilization of the gas digester production as the municipal gas source, reducing total operating expenses around 30 to 45% and costing the plant only $0.1 m−3. Maintenance of good granule production, which is always a key issue in operating UASB systems, was not possible by this installation, however, so frequent expensive reseeding of the reactor was often necessary due to biomass washout. The full scale and lab scale research revealed that underloading can be as detrimental as overloading, due to excessively long retention time in the UASB system for the overall operating period and to excessive pre-acidification and/or incorrect reactor configuration of the completely mixed type. To enhance the sludge granulation, therefore, the installation of a pre-acidification reactor in the UASB system treating easily biodegradable substrates such as brewery wastewater is not necessary because adequate pre-acidification can occur in the equalization tank.