Performance evaluation of subsurface wastewater infiltration system in treating domestic sewage

This study was to investigate domestic treatment efficiency of a subsurface wastewater infiltration (SWI) system over time. The performances of a young SWI system (in Shenyang University, China, fully operated for one year) and a mature SWI system (in Shenyang Normal University, China, fully operated for seven years) under the same operation mode were contrasted through field-scale experiments for one year. The performance assessment for these systems is based on physical and chemical parameters collected. The removal efficiencies within the young system were relatively high if compared with the mature one: for biochemical oxygen demand (BOD), chemical oxygen demand (COD), suspended solids (SS), ammonia nitrogen (NH(3)-N) and total phosphorus (TP) were 95.0, 89.1, 98.1, 87.6 and 98.4%, respectively. However, the removal efficiencies decreased over time. The mean removal efficiencies for the mature SWI system were as follows: BOD (89.6%), COD (87.2%), SS (82.6%), NH(3)-N (69.1%) and TP (74.4%). The results indicate that the mature SWI system successfully removed traditional pollutants such as BOD from domestic wastewater. However, the nutrient reduction efficiencies (including NH(3)-N and TP) decreased after seven years of operation of the mature SWI system. Meanwhile, the SWI system did not decrease the receiving surface water quality.     

Treatment of slaughterhouse plant wastewater by using a membrane bioreactor

The use of a membrane bioreactor (MBR) for removal of organic substances and nutrients from slaughterhouse plant wastewater was investigated. The chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP) concentrations of slaughterhouse wastewater were found to be approximately 571 mg O2/L, 102.5 mg/L, and 16.25 mg PO4-P/L, respectively. A submerged type membrane was used in the bioreactor. The removal efficiencies for COD, total organic carbon (TOC), TP and TN were found to be 97, 96, 65, 44% respectively. The COD value of wastewater was decreased to 16 mg/L (COD discharge standard for slaughterhouse plant wastewaters is 160 mg/L). TOC was decreased to 9 mg/L (TOC discharge standard for slaughterhouse plant wastewaters is 20 mg/L). Ammonium, and nitrate nitrogen concentrations of treated effluent were 0.100 mg NH4-N/L, and 80.521 mg NO3-N/L, respectively. Slaughterhouse wastewater was successfully treated with the MBR process.     

厌氧—接触氧化渠—垂直潜流型人工湿地处理农村生活污水研究

选择厌氧—接触氧化渠—垂直潜流型人工湿地工艺处理农村生活污水,分析比较了各工艺段DO水平,接触氧化渠充氧效果明显.通过对COD、NH3—N和TP浓度及去除率的研究发现,厌氧池去除率较稳定,对各污染物去除率最高可达72％、49.54％和66.36％,接触氧化渠和人工湿地对各污染物也有较高去除率,但并不稳定.系统运行稳定后,出水水质整体可达到《城镇污水处理厂污染物排放标准》(GB 18918-2002)二级标准,部分时段可达一级B标准.     

Performance of an in-situ rotating biological contactor in a recirculating aquaculture system

The start-up and activation of a nitrifying rotating biological contactor (RBC) and its performance inside a culture tank of rainbow trout were studied. First, in a lab-scale operation, the system was fed with a synthetic medium containing a high ammonia concentration (567 mg NH(4)(+)-N L(-1)) and operated at a high hydraulic retention time (HRT) (6.5 days) to minimize the wash-out of the biomass and promote the biofilm formation. Then, both inlet ammonia concentration and HRT were decreased in order to obtain operational conditions similar to those of the culture tank. During this period, the RBC was able to treat an ammonia loading rate (ALR) of 0.64 g N-NH(4)(+) L(-1) d(-1) with a removal efficiency within 70-100%. Pilot-scale experiments were carried out in culture tanks of rainbow trout. The operation of a recirculating system with the RBC unit was compared with a recirculating system without biological treatment and with a flow-through system. The use of this in-situ nitrifying unit allowed working at a recirculation ratio of 90% without negative effects on either growth or the condition factor of fishes. Up to 70% of ammonia generated was removed and a removal rate of 1.41 g NH(4)(+)-N m(-2) d(-1) was reached.     

3种微藻在龟鳖养殖废水中的生长与脱氮除磷特性

选取小球藻(Chlorella sp.)、栅藻(Scenedesmus sp.)和螺旋藻(Spirulina sp.)为试验藻种,分别接种于经沉淀池初步处理后排放的龟鳖养殖废水(取自无为县某养殖场,简称WW废水)和无任何处理直接排放的龟鳖养殖废水(取自大杨镇某养殖场,简称DY废水),考察3种微藻生长特性和对废水中氮磷的去除效果,比较其对龟鳖养殖废水的净化能力。结果表明:所选的3种微藻在两种废水中生长特性不同,DY废水中3种微藻细胞密度与生物量均大于其在WW废水中的相应指标,DY废水中小球藻、栅藻和螺旋藻的最大生物量分别为0.26 g/L、0.28 g/L和0.20 g/L。不同微藻对废水中氮磷去除效果各不相同,栅藻去除TN效果最好,最大去除率为93.65%,小球藻去除TP效果最好,最大去除率为99.46%,螺旋藻去除NH+4-N效果最好,最大去除率为98.79%。     

Design and operation of an eco-system for municipal wastewater treatment and utilization.

An eco-system consisting of integrated ponds and constructed wetland systems is employed in Dongying City, Shandong Province for the treatment and utilization of municipal wastewater with design capacity of 100,000 m(3)/d. The total capital cost of this system is 680 Yuan (RMB) or US dollars 82/m(3)/d, or about half that of the conventional system based on activated sludge process, and the O/M cost is 0.1 Yuan (RMB) or US dollars 0.012/m(3), only one fifth that of conventional treatment systems. The performance of the wastewater treatment and utilization eco-system is quite good with a final effluent COD, BOD, SS, NH3-N and TP of 45-65 mg/l, 7-32 mg/l, 12-35 mg/l, 2-13 mg/l and 0.2-1.8mg/l respectively and the annual average removals of COD, BOD, SS, NH3-N and TP are 69.1%, 78.3%, 76.4%, 62.1% and 52.9%o respectively, which is much better than that of conventional pond system or constructed wetland used separately and illustrates that the artificial and integrated eco-system is more effective and efficient than the simple natural eco-system.     

Fate of oestrogens during anaerobic blackwater treatment with micro-aerobic post-treatment.

The fate of oestrone (E1), 17beta-oestradiol (E2) and 17alpha-ethynyloestradiol (EE2) was investigated in a concentrated blackwater treatment system consisting of an UASB septic tank, with micro-aerobic post-treatment. In UASB septic tank effluent a (natural) total concentration of 4.02 microg/L E1 and 18.69 microg/L E2, comprising the sum of conjugated (>70% for E1 and >80% for E2) and unconjugated forms, was measured. During post-treatment the unconjugated oestrogens were removed to below 1 microg/L. A percentage of 77% of the measured unconjugated E1 and 82% of E2 was associated with particles >1.2 microm in the final effluent implying high sorption affinity of both compounds. When spiking the UASB septic tank effluent with E1, E2, EE2 and the sulphate conjugate of E2, removal in the micro-aerobic post-treatment was >99% for both E2 and EE2 and 83% for E1. The lower removal value for E1 was a result of (slow) deconjugation during the treatment, and in the final effluent still 40% of E1 and 99% of E2 was present in conjugated form. The latter was the result of incomplete deconjugation of the spiked E2(3S) in the post-treatment system.     

菌藻混合固定化及其对污水的净化实验

对菌藻共固定化系统进行研究,初步确定菌藻共固定化中较佳的污泥包埋量。在同等条件下,固定化菌藻对氮磷的去除效果优于固定化细菌和固定化藻类的去除效果。对氨氮和磷酸盐磷去除能力的48 h实验结果表明,按去除率的大小排列为:固定化菌藻固定化小球藻固定化细菌,固定化菌藻对NH4+-N和PO43--P的去除率分别达到97.09%和88.69%,可见把细菌和藻类共同包埋于同一载体内,在同时去除污水中的氮磷和有机物方面有着更大的优势。     

Operation of a full-scale pumped flow biofilm reactor (PFBR) under two aeration regimes

A novel technology suitable for centralised and decentralised wastewater treatment has been developed, extensively tested at laboratory-scale, and trialled at a number of sites for populations ranging from 15 to 400 population equivalents (PE). The two-reactor-tank pumped flow biofilm reactor (PFBR) is characterised by: (i) its simple construction; (ii) its ease of operation and maintenance; (iii) low operating costs; (iv) low sludge production; and (v) comprising no moving parts or compressors, other than hydraulic pumps. By operating the system in a sequencing batch biofilm reactor (SBBR) mode, the following treatment can be achieved: 5-day biochemical oxygen demand (BOD5), chemical oxygen demand (COD) and total suspended solids (TSS) reduction; nitrification and denitrification. During a 100-day full-scale plant study treating municipal wastewater and operating at 165 PE and 200 PE (Experiments 1 and 2, respectively), maximum average removals of 94% BOD5, 86% TSS and 80% ammonium-nitrogen (NH4-N) were achieved. During the latter part of Experiment 2, effluent concentrations averaged: 14 mg BOD5/l; 32 mg COD(filtered)/l; 14 mg TSS/l; 4.4 mg NH4-N/l; and 4.0 mg NO3-N/l (nitrate-nitrogen). The average energy consumption was 0.46-0.63 kWh/m3(treated) or 1.25-1.76 kWh/kg BOD5 removed. No maintenance was required during these experiments. The PFBR technology offers a low energy, minimal maintenance technology for the treatment of municipal wastewater.     

Performance of an ultra-compact biofilm reactor treating domestic and synthetic wastewaters

The performance of an ultra-compact biofilm reactor (UCBR) treating domestic wastewater (DWW) collected from a local water reclamation plant; and gradually shifting to a mono-type carbon source synthetic wastewater (SWW) combined with DDW (CWW) and finally SWW; was investigated in this study. The total COD concentrations of influent DWW and CWW/SWW were 413.6 ± 80.8 mg/L and 454.9 ± 51.3 mg/L, respectively. The UCBR was able to achieve average total COD removal efficiencies of 70 ± 10% and 80 ± 4% for DWW and SWW respectively. The total COD concentrations of the effluent of DWW and CWW/SWW were 122.5 ± 44.4 mg/L and 89.7 ± 10.3 mg/L, respectively. These observations suggested that heterotrophs in the UCBR system were able to better assimilate and remove carbon of mono-type SWW compared to diverse carbon sources such as DWW; although the influent soluble COD concentrations of the SWW were higher than those of the DWW. However, the effluent NH(4)(+)-N concentrations for both types of wastewater were rather similar, <3.0 mg/L; although the influent NH(4)(+)-N concentrations of the DWW were 1.5 times those of the SWW.     

河流滨岸带坡面对降雨径流的污染削减效应——以上海市樱桃河为例

选取上海市闵行区樱桃河畔具代表性的滨岸带地域,在模拟降雨过程中,设置不同坡度,不同坡长及植被条件下的对比实验。得出最优方案:坡度约为8°±0.5°,被冬青覆盖的河滨带在宽度为4~5 m时,对降雨径流的污染削减效果最佳。此时模拟地表径流平均入水质状况为,进水水质:ρ(COD)=154.7 mg/L、ρ(TP)=0.55 mg/L、ρ(NH3-N)=1.19 mg/L,出水水质:ρ(COD)=77.38 mg/L、ρ(TP)=0.29 mg/L、ρ(NH3-N)=0.69 mg/L;削减率分别为49.98%,47.27%,41.61%。试验结果为提高城市绿地规划与建设的合理性以及城市降雨径流非点源污染的控制提供参考。     

Enhanced removal of chemical oxygen demand, nitrogen and phosphorus using the ameliorative anoxic/anaerobic/oxic process and micro-electrolysis

Synthetic wastewater was treated using a novel system integrating the reversed anoxic/anaerobic/oxic (RAAO) process, a micro-electrolysis (ME) bed and complex biological media. The system showed superior chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) removal rates. Performance of the system was optimised by considering the influences of three major controlling factors, namely, hydraulic retention time (HRT), organic loading rate (OLR) and mixed liquor recirculation (MLR). TP removal efficiencies were 69, 87, 87 and 83% under the HRTs of 4, 8, 12 and 16 h. In contrast, HRT had negligible effects on the COD and TN removal efficiencies. COD, TN and TP removal efficiencies from synthetic wastewater were 95, 63 and 87%, respectively, at an OLR of 1.9 g/(L·d). The concentrations of COD, TN and TP in the effluent were less than 50, 15 and 1 mg/L, respectively, at the controlled MLR range of 75-100%. In this system, organics, TN and TP were primarily removed from anoxic tank regardless of the operational conditions.     

Degradation of organic matter from domestic wastewater with loofah sponge biofilm reactor

A laboratory-scale oxic biofilm reactor using loofah sponge as support material was carried out to study its start-up characteristics and the optimum operation parameters in removing organic matter and nitrogen from domestic wastewater. It took no more than 10 days to complete microbiological cultivation and acclimation, indicating that the natural loofah sponge was a superior support material compared with some conventional ones. The influence parameter experiments showed that the hydraulic retention time (HRT) had a significant influence on the COD and NH(3)-N removal efficiencies, the average COD and NH(3)-N removal efficiencies were 83.7 and 96.9% respectively when the temperature was 25 ± 2 °C, the influent flow rate was 0.21 L/h and the HRT was 7.5 h. The loofah sponge biofilm system had a strong tolerance to organic shock loading in the present experiment. Additionally, it was found that domestic wastewater could be preferably treated with 88.9% of COD and 98.7% of NH(3)-N removal efficiencies with the corresponding influent concentrations of 260.0 and 26.8 mg/L, respectively. The observations obtained in the present study indicated that the loofah sponge was an excellent natural support material, potentially feasible for the present system for the treatment of the decentralized domestic wastewater.     

藻华聚积及污水入流对太湖上下层水体营养盐含量的影响

通过采集太湖水体鲜藻和入湖区混合常见污水,应用再悬浮发生装置,室内模拟有底泥参与的不同藻类聚积和不同CODCr含量污水进入条件下,太湖西北竺山湖区水质上下层水体中SS,NH3-N及PO43-质量浓度的变化过程。分析结果表明:在7 d的常见风浪模拟环境中,无论加入藻类还是加入污水,太湖上下层水体中SS质量浓度均呈下降趋势,表明颗粒物有向水底沉降的可能;水体中的NH3-N和PO43-质量浓度并未因藻量增加而上升,反映出鲜藻此时对水体中的N和P呈吸收作用;污水添加量的增大则使试验水柱中NH3-N和PO43-质量浓度上升,并大致随时间的增加呈逐步上升的趋势。     

Floating treatment wetlands for domestic wastewater treatment

Floating islands are a form of treatment wetland characterized by a mat of synthetic matrix at the water surface into which macrophytes can be planted and through which water passes. We evaluated two matrix materials for treating domestic wastewater, recycled plastic and recycled carpet fibers, for chemical oxygen demand (COD) and nitrogen removal. These materials were compared to pea gravel or open water (control). Experiments were conducted in laboratory scale columns fed with synthetic wastewater containing COD, organic and inorganic nitrogen, and mineral salts. Columns were unplanted, naturally inoculated, and operated in batch mode with continuous recirculation and aeration. COD was efficiently removed in all systems examined (>90% removal). Ammonia was efficiently removed by nitrification. Removal of total dissolved N was ～50% by day 28, by which time most remaining nitrogen was present as NO(3)-N. Complete removal of NO(3)-N by denitrification was accomplished by dosing columns with molasses. Microbial communities of interest were visualized with denaturing gradient gel electrophoresis (DGGE) by targeting specific functional genes. Shifts in the denitrifying community were observed post-molasses addition, when nitrate levels decreased. The conditioning time for reliable nitrification was determined to be approximately three months. These results suggest that floating treatment wetlands are a viable alternative for domestic wastewater treatment.     

土壤过滤系统处理农村生活污水的 试验研究

采用一种土壤过滤系统处理农村生活污水,考察了该工艺对CODCr、BOD5、NH3-N、全氮（TN）和全磷（TP）的去除效果。实验结果表明,当水力负荷约为0.05 m3/（m2·d）, 水力停留时间为3 d时。该土壤过滤系统对CODCr、BOD5、NH3-N、全氮（TN）和全磷（TP）的去除效果较好,平均去除率分别达到84.6%、83.3%、64.3%、59.8%和70%。出水CODCr约为18.3~42.1 mg/L,BOD5约为8.9~17.3 mg/L,NH3-N约为11.2~17.7 mg/L,TN约为21.2~31.3 mg/L,TP小于2.0 mg/L,出水水质优于农田灌溉水质标准（GB 5084—2005）。气温变化和进水污染物浓度对处理效果影响明显。总体上来讲,温度大于22 ℃时,进水污染物浓度越低处理效果越好。     

MBR工艺处理城镇污水处理厂污泥水中试研究

将平板膜组件与传统脱氮除磷工艺相结合,构建了膜生物反应器强化生物脱氮除磷中试系统,并用于处理城镇污水处理厂的污泥系统废水。结果表明,出水CODCr、BOD5、NH3—N、TN和TP的平均浓度分别为70.8 mg/L、8.7 mg/L、15.1 mg/L、29.7 mg/L和0.38 mg/L,达到或接近了《城镇污水处理厂污染物排放标准》(GB 18918—2002)的一级标准。     

Effect of dosing regime on nitrification in a subsurface vertical flow treatment wetland system

In this study, the effect of dosing regime on nitrification in a subsurface vertical flow treatment wetland system was investigated. The experimental unit was composed of four circular concrete tanks (1 m diameter and 80 cm deep), filled with gravel (1-2 cm) and planted with Cyperus alternifolius L. Synthetic wastewater with average chemical oxygen demand (COD) and ammonia nitrogen of 1,151 and 339 mg/L was fed into each tank. Different feeding and resting periods were applied: continuous flow (tank 1), 4 hrs on and 4 hrs off (tank 2), 1 hr on and 3 hrs off (tank 3) and 15 minutes on and 3 hrs 45 minutes off (tank 4). All four tanks were under the same hydraulic loading rate of 5 cm/day. After 165 days the reduction of total Kjeldahl nitrogen and ammonia nitrogen and the increase of nitrate nitrogen were greatest in tank 4, which had the shortest feeding period, while the continuous flow produced the lowest results. Effluent tanks 2 and 3 experienced similar levels of nitrification, both higher than that of tank 1. Thus supporting the idea that rapid dosing periods provide better aerobic conditions resulting in enhanced nitrification within the bed. Tank 4 had the highest removal rates for COD, and the continuous flow had the lowest. Tank 2 also exhibited a higher COD removal rate than tank 3, demonstrating that short dosing periods provide better within-bed oxidation and therefore offer higher removal efficiency.     

Treatment of strong nitrogen swine wastewater in a full-scale sequencing batch reactor.

Treatment of swine wastewater containing strong nitrogen was attempted in a full-scale SBR. The strongest swine wastewater was discharged from a slurry-type barn and called swine-slurry wastewater (SSW). Slightly weaker wastewater was produced from a scraper-type barn and called swine-urine wastewater (SUW). TCOD, NH4+-N and TSS in raw SSW were 23,000-72,000 mg/L, 3,500-6,000 mg/L and 17,000-50,000 mg/L, respectively. A whole cycle of SBR consists of 4 sub-cycles with anoxic period of 1 hr and aerobic period of 3 hr. The maximum loading rates of both digested-SSW and SUW were similar to 0.22 kg NH4+-N/m3/day whereas the maximum loading rates of raw SSW was up to 0.35 TN/m3/day on keeping the effluent quality of 60 TN mg/l. The VFAs portion of SCOD in raw SSW was about more than 60%. The VFAs in SUW and digested-SSW were about 22% and 15%, respectively. NH4+-N and PO4(3-)-P in SSW were removed efficiently compared to those in digested-SSW and DUW because SSW had high a C/N ratio and readily biodegradable organic. High concentration of organic was useful to enhance denitrification and P uptake. Also the amount of external carbon for denitrification was reduced to 5% and 10% of those for digested-SSW and SUW.     

Removal of endocrine disrupting chemicals in a large scale membrane bioreactor plant combined with anaerobic-anoxic-oxic process for municipal wastewater reclamation

The removal of eight typical endocrine disrupting compounds (EDCs) in a full scale membrane bioreactor combined with anaerobic-anoxic-oxic process (A(2)/O-MBR) for municipal wastewater reclamation located in Beijing was investigated. These EDCs, including 4-octylphenol (4-OP), 4-n-nonylphenol (4-n-NP), bisphenol A (BPA), estrone (E1), 17α-estradiol (17α-E2), 17β-estradiol (17β-E2), estriol (E3) and 17α-ethinylestradiol (EE2), were simultaneously analyzed by gas chromatography/mass spectrometry after derivatization. The concentrations of eight EDCs were also measured in sludge of anaerobic, anoxic, oxic and membrane tanks to measure sludge-water distribution coefficients (K(d) values) as the indicator of adsorption propensity of target compound to sludge. The removal efficiencies of EDCs reached above 97%, except for 4-n-NP removal efficiency of 72%, 4-OP removal efficiency of 75% and EE2 removal efficiency of 87% in the A(2)/O-MBR process. The high K(d) values indicated that the sludge had a large adsorption capacity for these EDCs, and significantly contributed to removal of EDCs. Yeast estrogen screen assay was performed on samples to assess the total estrogenic activity by measuring the 17β-E2 equivalent quantity (EEQ), expressed in ng-EEQ/L. The measured EEQ value was markedly reduced from 72.1 ng-EEQ/L in the influent to 4.9 ng-EEQ/L in the effluent. Anoxic tank and anaerobic tank contributed to 80% and 37% in total EEQ removal, respectively.