Average COD Concentration Research Articles

Study on Operation Effect of Two-Stage MSL System for Rural Decentralized Sewage Treatment

To improve the removal efficiency of rural domestic sewage, a two-stage multi-soil-layer sewage treatment system with an “aeration section + non-aeration section” was designed, and its treatment performance was observed under different influent loads and aeration intensities. The experiment ran for a total of 150 days, and the results showed that the two-stage multi-soil-layer (MSL) system could effectively reduce the effluent concentration of sewage to meet discharge standards. Under the operating conditions of an influent hydraulic load of 1000 L·m−2·d−1 and an air–water ratio of 4:1, the final effluent average concentrations of COD, NH3-N, TN, and TP were 106.5 mg·L−1, 7.4 mg·L−1, 13.9 mg·L−1, 0.12 mg·L−1, and 18.6 mg·L−1, respectively, with average removal rates of 85.3%, 82%, 72.5%, 96%, and 85%. A longer hydraulic retention time and ideal anoxic conditions were ensured by designing a certain effluent height in the system. Adding aeration to the system allowed for a synchronous nitrification–denitrification reaction under reasonable influent loads, ultimately enabling the effluent to meet discharge standards.

Application of a pilot-scale solar still for wine lees management: characterization of by-products and valorization potential

Wine lees is a heavily contaminated by-product of wine making process. A pilot-scale solar still, equipped with an underfloor heating system, was used for dewatering the wine lees and recovering the evaporated water. Two solar distillation experiments were conducted, and the average distillate productivity rate ranged between 1.43 L/d·m2 and 3.86 L/d·m2. The higher productivity was observed at Experiment B when the daily maximum wine lees temperature in the still was 34.3 °C. The collected distillates were characterized by acidic pH and low conductivity while the average concentrations of COD and total phenols were ranged up to 82.5 g/L and 10.7 mg/L, respectively. UPLC-QToF-MS analysis revealed the existence of eighteen and five bioactive compounds in the wine lees and produced distillate, respectively, at concentrations up to 183 mg/kg and 12 mg/L for ethyl hydrogen succinate. Target screening analysis of the solid residuals allowed the quantification of seven bioactive compounds while four extra substances were identified via suspect screening. Ethyl hydrogen succinate was measured at the highest concentration (10.8 mg/kg) while the highest recovery was observed for 4-hydroxy-benzaldehyde (23.8%). The calorific values of the solid residuals exceeded 28 MJ/kg indicating their potential use as solid biofuels. Batch experiments showed that Chlorella sorokiniana can be grown in diluted distillates of the still. The higher average biomass productivity was observed for a dilution factor of 1:5 and it was equal to 31.4 mg/L per day. Analysis of the collected biomass indicated high lipid and starch content ranging up to 38.8% and 56.9%, respectively.

Simultanous Electricity Production and Wastewater Ttreatment in a Microbial Fuel Cell Inoculeted with Anaerobic Sludge

In order to reduce the environmental pollution associated with the conventional energy sources and to achieve the increased global energy demand, alterative and renewable sustainable energy sources need to be developed. Microbial fuel cells (MFCs) represent a bio-electrochemical innovative technology for pollution control and a simultaneous sustainable energy production from biodegradable, reduced compounds. This study mainly considers the performance of continuous up flow dual-chambers MFC fueled with actual domestic wastewater and bio-catalyzed with anaerobic aged sludge obtained from an aged septic tank. The performance of MFCs was mainly evaluated in terms of COD reductions and electrical power output. Results revealed that the COD removal efficiency up to 89% was obtained for wastewaters having an average initial COD concentration of 350 mg/L. Stabilized power outputs were clearly observed achieving a maximum value of 170 mW/ m2.

Long-term operation of cathode-enhanced ecological floating bed coupled with microbial electrochemical system for urban surface water remediation: From lab-scale research to engineering application

Ecological floating bed coupled with microbial electrochemical system (ECOFB-MES) has great application potential in micro-polluted water remediation yet limited by low electron transfer efficiency on the microbial/electrode interface. Here, an innovative cathode-enhanced EOCFB-MES was constructed with nano-Fe3O4 modification and applied for in-situ remediation both at lab scale (6 L, 62-day operation) and demonstration scale (2300 m2, 1-year operation). The cathode-enhanced ECOFB-MES exhibited superior removal in TOC (81.43 ± 2.05%), TN (85.12% ± 1.46%) and TP (59.80 ± 2.27%), much better than those of original ECOFB-MES and anode-enhanced ECOFB-MES in the laboratory test. Meanwhile, cathode-enhanced ECOFB-MES boosted current output by 33% than that of original ECOFB-MES, which made a great contribution to the improvement of ectopic electronic compensation for pollutant decontamination. Notably, cathode-enhanced ECOFB-MES presented high efficiency, stability and durability in the demonstration test, and fulfilled the average concentration of COD (9.5 ± 2.81 mg/L), TN (1.00 ± 0.21 mg/L) and TP (0.10 ± 0.04 mg/L) of effluent water to meet the Grade III (GB 3838–2002) with stable operation stage. Based on the KOSIM calculation, the removal loads of cathode-enhanced ECOFB-MES in carbon, nitrogen and phosphorus could reach 37.14 g COD/(d·m2), 2.62 g TN/(d·m2) and 0.55 g TP/(d·m2), respectively. According to the analysis of microbial communities and functional genes, the cathode modified by Fe3O4 made a sensible enrichment in electroactive bacteria (EAB) and nitrogen-converting bacteria (NCB) as well as facilitated the functional genes expression in electron transfer and nitrogen metabolism, resulting in the synergistic removal of carbon in sediment and nitrite in water. This study provided a brandnew technique reference for in-situ remediation of surface water in practical application.

Aerobic granular sludge development using diatomite for low-strength wastewater treatment

This paper presents an assessment of the start-up performance of aerobic granular sludge (AGS) for the treatment of low-strength (chemical oxygen demand, COD < 200mg/L) domestic wastewater by the application of a diatomite carrier. The feasibility was evaluated in terms of the start-up period and stability of the aerobic granules as well as COD and phosphate removal efficiencies. A single pilot-scale sequencing batch reactor (SBR) was used and operated separately for the control granulation and granulation with diatomite. Complete granulation (granulation rate ≥ 90%) was achieved within 20days for the case of diatomite with an average influent COD concentration of 184mg/L. In comparison, control granulation required 85days to accomplish the same feat with a higher average influent COD concentration (253mg/L). The presence of diatomite solidifies the core of the granules and enhances physical stability. AGS with diatomite recorded the strength and sludge volume index of 18 IC and 53mL/g suspended solids (SS) which is superior to control AGS without diatomite (19.3 IC, 81mL/g SS). Quick start-up and achievement of stable granules lead to an efficient COD (89%) and phosphate removal (74%) in 50days of bioreactor operation. Interestingly, this study revealed that diatomite has some special mechanism in enhancing the removal of both COD and phosphate. Also, diatomite has a significant influence on microbial diversity. The result of this research implies that the advanced development of granular sludge by using diatomite can provide promising low-strength wastewater treatment.

Integrated treatment of suburb diffuse pollution using large-scale multistage constructed wetlands based on novel solid carbon: Nutrients removal and microbial interactions

In this study, an integrated treatment system was proposed and applied in situ, including detention tank, multistage constructed wetlands (CWs) and wastewater treatment plants (WWTPs), preventing nutrients flowing into Dianchi Lake, in which the treatment performance of multistage CWs were evaluated principally. Results skillfully realized the bypass purification of upstream river at dry reasons, as well as the effective management and treatment of the collected diffuse pollution at rainy reasons. The purified water flowing into water bodies could satisfy the Grade III of environmental quality standards for surface water in China with the average effluent concentrations of COD, NH4+-N, TN and TP decreased to 10 (51.2–72.7%), 0.5 (67.2–83.0%), 1.0 (71.2–79.6%) and 0.15 (72.3–89.4%) mg L−1, respectively. High-throughput sequencing results indicated that the application of poly-3-hydroxybutyrate-cohyroxyvelate-sawdust (PS) blends could enrich norank_f_Anaerolineaceae (7.95%) and Bradyrhizobium (10.2%), which were distinct from the dominant genera of Pleurocapsa (13.0%) in gravel-based CWs. Functional genes and metabolism analysis uncovered that the heterotrophic denitrification was the main pathway of nitrogen removal with the abundance of genes encoding TCA cycle, glycolysis and denitrification process up-regulated. In addition, molecular ecological network (MEN) analysis suggested the denitrification genes were positively correlated with the predominant microbes in PS-based CWs, favorable for denitrifiers to transfer and utilize electron donors during denitrification process. This study proved that the developed PS blends as carbon supplies in CWs and the proposed integrated treatment system are effective methods for watershed management, providing valuable reference to low-pollution wastewater treatment in practical engineering projects.

Increasing the energy production in an urban wastewater treatment plant using a high-rate activated sludge: Pilot plant demonstration and energy balance

The use of high-rate activated sludge (HRAS) reactors for the removal of COD in urban wastewater treatment plants (WWTPs) has been investigated because its potential contribution to energy generating WWTPs. A one-year operation period of a pilot plant treating the effluent of the primary settler of a full-scale WWTP was analyzed. The HRAS pilot plant operated without iron salts addition at temperatures between 12 and 28 °C at an average organic loading rate 2.8 ± 0.5 kg COD m−3 d−1 and with an average inflow COD concentration of 330 ± 86 mg O2 L−1. The influence of sludge retention time (SRT) on COD recovery and biomethane potential of the produced sludge was investigated and compared to the full scale WWTP performance. The highest observed sludge yield coefficient and biomethane potential of the sludge were achieved at SRT of 0.6 days. The weak point of the HRAS performance at STR of 0.6 days is the high loss of organic matter in the effluent due to the limited efficiency of the solids separation in the secondary settler. At higher SRT (in the range 1.0–2.1 days), the secondary settler efficiency and the COD recovery are higher than those achieved at SRT of 0.6 days but part of the inlet ammonium can be nitrified in the HRAS system at temperatures above 20 °C. A detailed energy balance indicated that two-thirds reduction of aeration requirements and one-third increase of biogas production could be achieved in a plant configuration in which HRAS is coupled to autotrophic biological nitrogen removal (BNR) compared to the heterotrophic BNR configuration, yielding a net energy production of ca. 0.1 kWh m−3 of treated water.

Analysis on the Source Tracing and Pollution Characteristics of Rainfall Runoff in the Old Urban Area of Nanning City

Rainfall runoff is one of the important sources of urban river pollution. In order to understand the pollution characteristics of rainfall runoff, the synchronous sampling and monitoring of rainfall runoff in the old urban area of Nanning were carried out; the pollution condition, initial scouring effect, and pollution contribution ratio of different underlying surfaces under different rainfall conditions were analyzed; and the calculation method and influence factor analysis of initial scouring of runoff pollution were discussed. According to the underlying surface of the vegetable market in the old urban area, the selection standard and necessity of the underlying surface of rainfall runoff were discussed. The results showed that the average concentration (EMC) of COD and TSS in roads and vegetable markets were greater than those in green spaces and roofs in the runoff pollution of the old urban area of Nanning, and the EMC values of nutrient pollutants in field rainfall runoff were ranked in decreasing order as vegetable markets, green spaces, roofs, and roads. Under the condition of heavy rain, each underlying surface had an obvious initial scouring effect, the average value of initial scouring coefficient (b) was 0.67, and there were many pollutants transported by roads and green spaces at the initial stage. Under light rain and moderate rain conditions, there was no obvious initial scouring effect, and the average b values were 0.83 and 0.94, respectively. The b value calculated by the whole process was preferred for evaluating the scouring effect. Based on multivariate statistical analysis, the EMC value of TSS in road runoff was significantly positively correlated with the total rainfall duration (RD), and the EMC value of TN in green land runoff was significantly negatively correlated with the average rainfall intensity (ARI). Whether the vegetable market was considered as the underlying surface had a great impact on the calculation results of nutrient pollution load but had little impact on the calculation results of COD and TSS load. The difference percentage of nutrient pollution load under heavy rain reached 80%. Under this condition, the difference percentage of pollutant EMC between the road and vegetable market reached 1012%.

Pollutant removal from swine wastewater and kinetics in constructed rapid infiltration system (CRI system)

ABSTRACT The purpose of this paper is centred on the kinetics of removal of main pollutants in wastewater and to compared different hydraulic loading conditions of the constructed rapid infiltration system (CRI system) in terms of removal efficiencies, effluent concentrations, mass removal rate (MRR), and the first-order removal rate coefficient (k) of COD, TOC, NH4 +-N, TN, and TP. The results showed that the higher the hydraulic loading, the higher the effluent concentration. The results that synthesized hydraulic loading, effluent concentrations, removal efficiencies, and other conditions showed that the best hydraulic loading was 40 cm/d. When the hydraulic load was 40 cm/d, the effluent average concentrations of COD, TOC, NH4 +-N, TN, TP, Cu2+ and the removal efficiencies were 27.31 ± 16.40 mg/L, 86.11%, 10.55 ± 5.25 mg/L, 84.64%, 0.59 ± 0.87 mg/L, 99.60%, 143.31 ± 14.77 mg/L, 7.04%, 5.64 ± 1.38 mg/L, 79.20%, and 0.13 ± 0.47 mg/L, 97.51%, respectively. According to a kinetic study of the primary pollutants, the MRR increased with an increase in the hydraulic loading, except for ammonia nitrogen. CRI-3, CRI-4 were high significant correlated with ammonia nitrogen (with R 2 = 93.65% and R 2 = 95.03%, respectively), while CRI-2, CRI-3, and CRI-4 were high significant correlated with total nitrogen (with R 2 = 94.56%, R 2 = 96.70% and R 2 = 96.56% respectively).

Assessing pollution profiles along Little Akaki River receiving municipal and industrial wastewaters, Central Ethiopia: implications for environmental and public health safety

Little Akaki River drains residential, industrial, and agricultural irrigation areas of Addis Ababa City Administration and is exposed to point and non-point sources of pollution. The purpose of this study was to identify sources, evaluate the levels of river water pollution, and its implications for environmental and public health. Pollution indices and multivariate statistical analyses were used to determine sources and levels of the river water pollution. Trace metals concentration was determined using inductive coupled plasma optical emission and spectrophotometer (ICP-OES). The average concentrations of COD, BOD, TDS, NO3–N, NH3–N, SO4−2, and PO4−3 ranged from 40. 33 ± 5. 13 to 425 ± 8. 00 mg/L; 12.34 ± 0.11 to 188 ± 7.07 mg/L; 48.00 ± 0.83 to 915. 57 ± 1. 27 mg/L; 1.56 ± 1.01 to 66.50 ± 6.36 mg/L; 0.15 ± 0. 08 to 42.83 ± 11.43 mg/L; 20.50 ± 10.61 to 77.50 ± 17.68 mg/L; and 0.35 ± 0.33 to 37.95 ± 0.92 mg/L, respectively. The average concentrations of Zn ranged (0.048 ± 0.037 to 0.318 ± 0.158 mg/L), Cr (0.012 ± 0.007 to 0.203 ± 0.199 mg/L), Cd (<0.014 ± 0.0007 to 0.02 ± 0.001 mg/L) and Pb (0.031 ± 0.008 to 0.124 ± 0.034 mg/L). The comprehensive water pollution index values varied from 0.84–13.32, indicating that at all sampling sites (except for sampling site S1), the river water was heavily polluted (CPI >2.01). Heavy metal pollution index values further demonstrated potential environmental and public health implications. The principal component analysis revealed a total of 88.99% variation in the dataset, mainly contributed by organic matter, nutrients, dissolved salts, and trace metals that originated from anthropogenic sources. Contamination of the river water has impaired its suitability for urban agriculture, aquaculture, livestock drinking, and recreational purposes. Thus, improving the river water quality is recommended to mitigate potential adverse effects and promote sustainable use of water resources.

Environmental assessment of refectory waste based on approaches zero-waste project in Turkey: the production of biogas from the refectory waste.

The zero-waste project in Turkey, which was started in 2017, is planned to be implemented until 2023, starting from public institutions and organizations. However, in refectories where high amounts of organic waste are generated, these organic wastes are generally transported to the landfill site by the municipalities and, consequently, they go beyond the scope of the zero-waste project. In this study, the anaerobic treatment of refectory wastes based on the scope of the zero-waste approach in Turkey has been developed as an innovative and holistic approach. As a result of the informing studies in the refectories, the waste of bread could be zero, while the waste of meals could not be zero, but a significant decrease in meal waste was found. In addition, this holistic approach has also strengthened recycling. Anaerobic digestion was selected to complete the zero-waste target for food wastes that are still generated. In the study using the UASB reactor operated in mesophilic conditions (36.5-37°C), feeding has been done with approximately 21.9kg VSadded m-3 OLR in 10-day HRT. As a result, it was observed that the production of biogas and organic fertilizers from food waste using anaerobic technologies is an important solution on behalf of realizing the zero-waste application. The results showed that 1kg of food waste with 62 ± 3.2% solid content could produce 640 L of biogas with approximately 62.2 ± 0.6% methane content. In addition, a 26.2-L bio-fertilizer with an average COD concentration of 3354 ± 106 mg L-1 was produced. This research paper with a successful method at the Adıyaman University in Turkey focuses on the goal of zero waste. This study illustrated how it is possible to implement an effective initiative to reduce food waste with a holistic approach.

Novel pyrrhotite and alum sludge as substrates in a two-tiered constructed wetland-microbial fuel cell

Integrated constructed wetland-microbial fuel cells (CW-MFCs) use exoelectrogenic bacteria to transform the energy inherently existed in wastewater into bioelectricity and simultaneously remove the contaminants in wastewater. They have the potential to provide a solution for both water and energy challenges. In this study, a novel two-tiered CW-MFC system consisted of a dewatered Al-DWTR-based up-flow CW-MFC (Top CW-MFC) and a pyrrhotite-based downflow CW-MFC (Bottom CW-MFC) was constructed. The two-tiered CW-MFC system was operated under different COD concentrations, HRTs and operation modes over a 477-day trial. The treated effluent had an overall average COD concentration of 69.05 mg/L. High power density of the top CW-MFC of 741.36 mW/m3 (A1-C) and 339.56 mW/m3 (A2-C) at HRT of 2.49 d (Phase 7) with continuous flow and 1162.63 mW/m3 (A1-C) and 352.34 mW/m3 (A2-C) with tidal flow (Phase 10), respectively, was achieved. Co-occurrence of Feammox and iron sulphide-based denitrification were found in bottom CW-MFC, leading to the enhanced nitrogen removal in the system. The genera of SRB (Desulfosporosinus, Desulfobulbus, Desulfobacca, Desulfovibrio and members of Desulfobacteraceae), exoelectrogenic bacteria enriched in the system resulted in a low release of sulfate, and effective pollutant removal and bioelectricity production. The findings highlight the novel two-tiered CW-MFC system for efficient wastewater treatment and high performance of energy extraction, supporting a clean environment.

Effect of Media on Treatment of Settled Domestic Sewage Using Hybridized Anaerobic Baffled Reactors.(Dept.C)

This research work aimed at obtaining a low cost sustainable technology for domestic wastewater treatment for Egyptian rural areas. To make this come through, a high rate hybirdized anaerobic baffled reactor (HABR) was pilot tested for a period of about 18 months in order to assess the state of art and the technical and economic efficiency of this system. This pilot reactor consisted of four reactors with different media (HABR1, HABR2, HABR3 and HABR4) were constructed and each reactor had a total volume of 800 liters and consists of four compartments. Plastic media and gravel were used and had specific surface area of 100 and 80 m2/m3respectively. The average influent COD concentration was about 300 mg/1. The overall HRTs tested were 3.5, 2.5, 1.0 and 0.5 days with average influent organic loadings in the range from 0.05 to 0.25 Kg BOD5/m3.day. High substrate removal rates can be achieved in a HABR fed with low substrate levels of only 300 mg/lit of COD. At an HRT of 3.5 days, HABR) with plastic media gave an average BOD5 removal rate of 79% with an effluent of 25 mg/lit. This was the highest removal value recorded as the other reactors HABR2, HABR3 and HABR4 gave 60.5%, 71.5% and 75.6% respectively for the same HRT, In a likewise manner, the COD removal rates recorded at the same HRT were 85.7%, 80%, 83.3% and 85.7% respectively. Suspended solids removal rates were the highest and recorded a value of 90.3% for a HRT of 3.5 days for HABR1. At the same HRT the removal rates for HABR2, HABR3 and HABR4 were 76.8%, 86.5% and 89% respectively. For HABRI the HRT of 0.5 days. The highest COD value recorded was at a HRT of 0.5 days BODs removal rates dropped from 79% at a HRT of 3.5 days to about 50.5% at a HRT of 0.5 days. This was also the case with the other three reactors and the lowest removal rate recorded was 33.7% for HABR2 at for HABR2 with a value of 101.2 mg/lit. While the highest SS value recorded was 72.4 mg/lit with a percentage removal of 58.8% for HABR3 at a HRT of 0.5 days. This system provides potential attractive possibilities for application in small communities with a population of less than 5000 capita.

Spatiotemporal change analysis of permanganate index in the middle and lower mainstem of the Yangtze River since 2004

高锰酸盐指数是我国水环境质量评价和污染控制考核的重要指标，其浓度高低能反映水体受到有机物污染的严重程度.2003年三峡水库投入运行后，长江中下游干流水文情势发生了重大变化.为此，研究了长江中下游干流耗氧有机污染物的典型参数——高锰酸盐指数的时空变化特征.结果表明，长江中下游干流水体：2004年以来，高锰酸盐指数总体趋降，且目前已处于较低水平并趋于稳定；不同江段和水期高锰酸盐指数变化趋势不一致；耗氧有机污染物以溶解态为主，且溶解态所占比例沿程趋于降低，南津关、汉口、吴淞口下23 km断面溶解态占比中位值分别为0.862、0.734和0.598；可沉降颗粒物对水体中高锰酸盐指数浓度影响较低，尤其在研究河段上游段，悬浮颗粒中所含耗氧物质占总量比例中位值分别为0.138、0.266和0.402；上游江段水体同一监测断面不同测线和测点间高锰酸盐指数测定值差异不显著；河口段则存在显著差异，尤其是表层和底层之间；沿江城市江段近岸水域水体中耗氧物质污染程度较低，其澄清样中高锰酸盐指数均值在1.91～3.45 mg/L之间，仅局部城市江段和水期出现值高于6.0 mg/L的现象.;Permanganate index (COD_Mn) is an important parameter for water quality assessment and pollution control supervision in China. Its concentration reflects the severity of organic pollution. Since the Three Gorges Reservoir was put into operation in 2003, the hydrological condition of in the middle and lower Yangtze River mainstem has been changed significantly. Therefore, the characteristics of spatiotemporal distributions of organic substances(OS) corresponding to permanganate index in the middle and lower mainstem of the Yangtze River under new hydrological condition were studied. The results show that in the middle and lower reaches of the Yangtze River: Since 2004, COD_Mn has been decreasing generally, and it is currently at a low level and tends to stabilize. The trend of COD_Mn in the different river sections and the water period is inconsistent. OS(COD_Mn) in the water column are mainly in the dissolved state, and the proportion of the dissolved state tends to decrease along the direction from upstream to downstream. The median values of C_clarified/C_original ratio in Nanjinguan, Hankou and 23 km below Wusongkou, are 0.862, 0.734 and 0.598 respectively. The effect of the precipitable particles on the COD_Mn concentration in the water is low, especially in the upstream section. The median values of (1-C_filtered/C_original) ratios in Nanjinguan, Hankou and 23 km below Wusongkou were 0.138, 0.266 and 0.402, respectively. There is no significant difference between the different lines and measuring points in the transverse profile in the section on upstream end of studied reach, but significant difference in the estuary section, especially between the surface layer and the bottom layer in the vertical direction. Oxygen-consumed organic pollution is not serious in the coastal waters of urban reaches, and the average concentration of COD_Mn of the clarified samples is between 1.91 and 3.45 mg/L, and the concentration value is seldom higher than 6.0 mg/L.

Pilot Scale Study on Combined Ultra Filtration and Other Technique to Treat Rural Domestic Sewage

The rural domestic sewage was treated by using combined ultra filtration with reverse osmosis (RO), constructed wetlands and biofilter respectively. The results showed that the average concentrations of COD, TP, NH4-N and TN in the effluent were 118.1, 5.4, 75.5 and 85.0 mg/L, and the average removal rates were 77.0%, 58.1%, -2.7%, and 15.1% by ultra filtration respectively. And then the effluent treated by RO process, the above water quality indicators had reached the I A level of the discharge standard of pollutants for urban wastewater (GB18918-2002). The average removal rates of COD were 35.6% and 35.1%, TP were 11.9% and 9.8%, NH4-N were 5.4% and 23.7%, TN were 6.1% and 7.6% by constructed wetlands and biofilter respectively. The overall removal rates of pollutants were not high and the effluent quality was not stable through the above two techniques. Therefore, further improvement is needed in design and operation of constructed wetlands and biofilter. Ultra filtration-reverse osmosis integrated equipment can be designed to treat dispersed domestic sewage in rural areas.

Removal performance of high hydraulic loading rate subsurface wastewater infiltration systems with added Si[sbnd]Al porous clay material and scrap iron filings

To enhance pollutant removal performance in the treatment of decentralized domestic sewage, a subsurface wastewater infiltration system (SWIS) with turfy soil was improved by adding SiAl porous clay material W (PCMW) and scrap iron filings. The permeability at different depths of the SWIS was improved. Under the conditions of 186.18 ± 34.82 mg/L COD, 25.84 ± 2.57 mg/L NH4+-N, 3.02 ± 0.91 mg/L NO3−-N, 33.87 ± 3.78 mg/L TN, 6.93 ± 1.21 mg/L TP, a 0.28 m3/m2·d hydraulic loading rate and 716 d operation time, the average effluent concentrations of COD, NH4+-N, NO3−-N, TN and TP were 31.28 ± 5.87 mg/L, 3.39 ± 1.42 mg/L, 3.71 ± 0.87 mg/L, 7.11 ± 0.97 mg/L and 0.24 ± 0.07 mg/L, respectively, and the TN removal efficiency increased by 20.7% compared with that of the control SWIS. According to the pollutant variations with depth, 76.79% COD, 80.96% NH4+-N and 95.35% TP were removed at a depth of 110 cm, after which their concentrations remained stable; the TN concentration decreased with depth and was quite different from that of control SWIS, NH4+-N in TN was removed at a depth of 0–90 cm, and NO3−-N in TN was removed at 90–170 cm depth. Moreover, both the number of nitrifying/denitrifying bacteria and nitrate/nitrite reductase activity reached their maximum at 90 cm depth. Adding PCMW and scrap iron filings to SWISs could be an ideal method to improve the performance and service life of SWISs.

Pilot-scale anoxic/aerobic biofilter system combined with chemical precipitation for tertiary treatment of wastewater

In this study, a pilot-scale anoxic/aerobic biofilter system combined with chemical precipitation was devised and applied for the tertiary treatment of nitrogen, and post-treatment of phosphorus and residual organics in effluent from existing wastewater treatment facilities. When the system operated under a system hydraulic retention time (HRT) of 5.98 h, nitrified effluent recirculation ratio of 0.5, average methanol-supplement concentration of 23.2 mg/L, and average aluminum-sulfate concentration of 2.37 mg/L, the average concentration of BOD5, COD, SS, TN, and TP in the system effluent were 3.3, 10.4, 4.2, 6.1, and 0.43 mg/L, respectively. Despite the shorter HRT of 1.35 h in the anoxic filter packed with media, noticeable denitrification was achieved rapidly. A perfect nitrification rate was achieved and no clear deterioration in performance by chemical addition was observed. Thus, the system achieved not only outstanding nitrogen-removal performance, but also the additional removal of residual organics and phosphorus.

Tendency and Causes Analysis of Marine Water Quality of Jinzhou Bay

Based on the two monitoring data of Jinzhou Bay in July 2008, September 2013 and September 2016, this article analysis the temporal trends of marine water quality of Jinzhou Bay. The average concentration of COD, inorganic nitrogen and phosphate is between 1.09mg/L~1.45mg/L, 0.42mg/L~0.711mg/L and 0.006mg/L~0.03mg/L, respectively. The concentration of inorganic nitrogen showed a downward trend while the concentration of phosphate showed an increased trend. Meanwhile, the concentration of COD had no significant change. Results showed that the inorganic nitrogen concentration and phosphate concentration have good correlation with eutrophication index and Eutrophication parameters（E）showing a clear upward trend. The emission of active phosphates and inorganic nitrogen from land-based pollutants are the main cause of this phenomenon.

Biological nitrogen removal and metabolic characteristics in a full-scale two-staged anoxic-oxic (A/O) system to treat optoelectronic wastewater

In order to explore the treatment efficiency of optoelectronic wastewater and pollutant degradation mechanism of full-scale two-stage AO process, 160 d monitoring was conducted in this study. The results showed that the two-stage AO process owned relatively stable nitrogen and organic matter removal performance. The average concentration of COD, NH4+-N, and TN in effluent was 54, 3.78 and 13.77 mg L−1, respectively, and the removal rate was over 80%. The results of high-throughput sequencing demonstrated that the dominant microorganism was Proteobacteria, Bacteroidetes, Firmicutes, Chlorofeli, and Acidobacteria, and differences of interaction networks exited between aerobic and anoxic units. Meanwhile, the microorganism metabolism in aerobic units was significantly different from that in anoxic unit, and the metabolism of the microbial community for treating optoelectronic wastewater was significantly different from that for treating urban domestic sewage.

Design and operation effect of corn starch wastewater treatment project

The corn starch wastewater was treated by the combination of “IC anaerobic + two-stage AO biochemical + modified Fenton”. The design parameters and treatment effects of the main construction sections of the project were introduced. The operation results of the project show that the combined process has a good treatment effect on corn starch wastewater. In the case where the average concentration of COD in the influent water is 17640 mg/L, the average concentration of NH3-N is 91.1 mg/L, and the average concentration of TN is 1266 mg/L. The average concentration of the COD, NH3-N and TN in the effluent water after treatment are 36mg/L, 1.2mg/L and 11.6mg/L, respectively, which meets the design standard requirements. The process control method of using some high-concentration organic wastewater beyond the anaerobic section can achieve the standard treatment of total nitrogen without the need of external supplementary carbon source, which has significant economic benefits.