Treatments of oil-refinery and steel-mill wastewaters by mesocosm constructed wetland systems.

In this study, two types of industrial wastewater, oil-refining and steel-milling, were selected for investigating their feasibility of treatment by mesocosm constructed wetland systems. The secondly treated effluents from the wastewater treatment plants were directly discharged into the systems controlled at different flow rates. Three wetland mesocosms were installed in the two industries: mesocosms A and B were in the oil refinery, and mesocosm C was in the steel mill. The substratum media used in wetland systems were sand (mesocosm A) and gravel (mesocosms B and C), while the vegetation types selected were reeds (mesocosms A and B) and mixed species of reeds and cattails (mesocosm C). The flow regimes were controlled as free water surface (FWS) and subsurface flow (SSF) for the sand- and gravel-beds, respectively. According to the experimental results, we found that the system treating oil-refining wastewater performed better than that treating steel-milling wastewater learned by comparing the removal efficiencies of COD, total N and total P. In addition, it was found that for oil-refining wastewater treatments, the SSF wetland system (mesocosm B) performed better than FWS (mesocosm A) wetland system when comparing both of their removal of pollutants and growth of vegetation. Besides, the effluents from these two industrial wetland treatment systems might be reclaimed and reused for boiler water, cooling, cleaning and miscellaneous purposes in industries. Further treatments are required if the constructed wetland effluents are thought about being reused for processing in industries.     

Effect of recirculation on organic matter removal in a hybrid constructed wetland system

This research project aimed to determine the technologically feasible and applicable wastewater treatment systems which will be constructed to solve environmental problems caused by small communities in Turkey. Pilot-scale treatment of a small community's wastewater was performed over a period of more than 2 years in order to show applicability of these systems. The present study involves removal of organic matter and suspended solids in serially operated horizontal (HFCW) and vertical (VFCW) sub-surface flow constructed wetlands. The pilot-scale wetland was constructed downstream of anaerobic reactors at the campus of TUBITAK-MRC. Anaerobically pretreated wastewater was introduced into this hybrid two-stage sub-surface flow wetland system (TSCW). Wastewater was first introduced into the horizontal sub-surface flow system and then the vertical flow system before being discharged. Recirculation of the effluent was tested in the system. When the recirculation ratio was 100%, average removal efficiencies for TSCW were 91 +/- 4% for COD, 83 +/- 10% for BOD and 96 +/- 3% for suspended solids with average effluent concentrations of 9 +/- 5 mg/L COD, 6 +/- 3 mg/L BOD and 1 mg/L for suspended solids. Comparing non-recirculation and recirculation periods, the lowest effluent concentrations were obtained with a 100% recirculation ratio. The effluent concentrations met the Turkish regulations for discharge limits of COD, BOD and TSS in each case. The study showed that a hybrid constructed wetland system with recirculation is a very effective method of obtaining very low effluent organic matter and suspended solids concentrations downstream of anaerobic pretreatment of domestic wastewaters in small communities.     

Integrated advanced natural wastewater treatment system for small communities.

A study was conducted to evaluate the nutrient removal capability of an existing and successfully operated overland flow and wetland wastewater treatment system following a waste stabilization pond. Seasonal temperature effects on performance were also investigated. The treatment system studied consists of a two-cell waste stabilization pond followed by an overland flow system and a wetland system. The influent and effluent samples were analyzed for BOD5, suspended solids (SS), pH, temperature, ammonia nitrogen, nitrate nitrogen, and total phosphorus. The results of the study indicate that the combined pond, overland flow and wetland system provided excellent treatment of municipal wastewater. The overall average BOD5 removal by the entire treatment system was about 90.0% and the overall average suspended solids removal was about 93.4%. The ammonia nitrogen and total phosphorus removal efficiencies of the entire treatment system were 90.7% and 84.2%, respectively.     

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.     

Integrated natural treatment systems for developing communities: low-tech N-removal through the fluctuating microbial pathways.

Integration of natural treatment systems (NTS) (WSP, wetlands etc.) with each other as well as with advanced unit processes (biofiltration) offers a second lease of life to NTS. Long-term full and pilot cale experience in South Africa and Thailand have shown that contrary to a common view, a low tech N-removal from municipal and light industrial wastewater is a reality for a developing community The high treatment efficiency is ascribed to interplay of N-related processes complementing each other. The present FISH-based (Fluorescence In Situ Hybridization) approach to microbial community structure is a pioneering effort in the field of NTS. It establishes interrelationships between major N-removing groups (aerobic and anaerobic ammonia oxidizers (ANAMMOX), denitrifiers) within integrated systems and links them to the high treatment performance. Seasonally fluctuating presence of the ANAMMOX bacteria (0-2.5% of total bacterial numbers) in the NTS (free surface flow wetland) is reported for the first time. Their numbers correlate with metabolically dependent ammonia-oxidizers (2.0-3.0%) but not with stable overall Planctomycetes population (4.5-5.1%). As a result of the flexible microbial structure the robust low cost removal down to TN < 10 mg/L is routinely feasible at the loading rates ranging from 0.005 to 0.08 TN kg/m3/day.     

微波-活性炭联用对焦化废水中氨氮和COD的同时去除研究

工业生产中未达标的废水直接排放是导致湖泊等受纳水体污染的一个重要原因。以焦化企业生化外排水为处理对象,采用微波－活性炭联用技术对废水中的NH³-N和COD进行同时去除研究。结果表明：随着活性炭用量的增加,COD去除率逐步增大,而NH³-N的去除率逐步下降;微波功率和辐射时间的增加有利于污染物的去除;采用微波-活性炭联用进行动态水处理试验时,废水中NH³-N和COD去除率分别可达85.3%和60.3%。此研究为工
业废水的治理提供了新的思路。     

Electrically enhanced MBR system for total nutrient removal in remote northern applications

Thousands of sparsely populated communities scatter in the remote areas of northern Canada. It is economically preferable to adopt the decentralized systems to treat the domestic wastewater because of the vast human inhabitant distribution and cold climatic conditions. Electro-technologies such as electrofiltration, elctrofloatation, electrocoagulation and electrokinetic separation have been applied in water and conventional wastewater treatment for decades due to the minimum requirements of chemicals as well as ease of operation. The membrane bioreactor (MBR) is gaining popularity in recent years as an alternative water/wastewater treatment technology. However, few studies have been conducted to hyphenate these two technologies. The purpose of this work is to design a novel electrically enhanced membrane bioreactor (EMBR) as an alternative decentralized wastewater treatment system with improved nutrient removal and reduced membrane fouling. Two identical submerged membranes (GE ZW-1 hollow fiber module) were used for the experiment, with one as a control. The EMBR and control MBR were operated for 4 months at room temperature (20 ± 2 °C) with synthetic feed and 2 months at 10 °C with real sewage. The following results were observed: (1) the transmembrane pressure (TMP) increased significantly more slowly in the EMBR and the interval between the cleaning cycles of the EMBR increased at least twice; (2) the dissolved chemical oxygen demand (COD) or total organic carbon (TOC) in the EMBR biomass was reduced from 30 to 51%, correspondingly, concentrations of the extracellular polymeric substances (EPS), the major suspicious membrane foulants, decreased by 26-46% in the EMBR; (3) both control and EMBR removed >99% of ammonium-N and >95% of dissolved COD, in addition, ortho-P removal in the EMBR was >90%, compared with 47-61% of ortho-P removal in the MBR; and (4) the advantage of the EMBR over the conventional MBR in terms of membrane fouling retardation and phosphorus removal was further demonstrated at an operating temperature of 10 °C when fed with real sewage. The EMBR system has the potential for highly automated control and minimal maintenance, which is particularly suitable for remote northern applications.     

炼油污水深度处理的应用实例及处理效果

介绍了某石化炼油污水处理的工艺流程、运行状况等。通过对深度处理工艺的运行状况及去除效果可以看出：对COD、氨氮、石油类物质、浊度的去除率分别为80.4%、89.7%、89.1%、71.3%,均有较好的去除效果。该工程实例可以为炼油污水的深度处理提供有价值的参考。     

A combined UASB-MBR with shortcut nitrification-denitrification for energy reduction in wastewater reclamation

Shortcut nitrification has been successfully applied in a laboratory scale nitrification-denitrification process consisting of an up-flow anaerobic sludge blanket (UASB) and an aerobic membrane bioreactor (MBR) in treating synthetic and municipal wastewater to simultaneously remove organic carbon and nitrogen. For the treatment of synthetic wastewater, the combined system exhibited a high TOC removal of 98% with a steady ammonia removal efficiency of about 98% in the MBR and a total nitrogen (TN) removal efficiency of 90%. In treating municipal wastewater, due to its low COD concentration, removal efficiencies of TOC, ammonia and TN were 70%, 98% and 60%, respectively. The biogas production was around 76.4 L/m3 wastewater when treating synthetic wastewater. However, little biogas was produced when treating municipal wastewater which was the result of low organic carbon loading to the UASB. Energy analysis has demonstrated that this novel shortcut nitrification process could consume less energy than a conventional process and have the potential of bio-energy generation via biogas production thus helping to achieve a more favorable energy balance.     

Winery wastewater treatment by constructed wetlands and the use of treated wastewater for cash crop production.

A 45 m long, 4 m wide and 1 m deep wetland was constructed at Goudini in 2002 to treat distillery and winery effluent. After the plants were fully established, the wastewater with an average chemical oxygen demand (COD) of 14,000 mg/l was introduced to the wetland system at a rate of 4,050 litres per day. After treatment, wastewater at the outlet had an average COD of 500 mg/l, indicating more than 90% COD removal. After treatment, the wastewater was used to irrigate cash crops as part of poverty alleviation for farm workers. The experiment consisted of four treatment: clean irrigation water with fertilizer applied (B1); clean irrigation water without fertilizer applied (B2); wastewater irrigation with fertilizer applied (B3); and wastewater irrigation without fertilizer applied (B4). These were replicated seven times. Cabbage was cultivated as a cash crop. The results indicated that cabbage could be irrigated with winery wastewater treated by wetlands. The study found that there was significant difference between treatments that were fertilized compared with those that were not fertilized. The results indicated that wastewater irrigation improved the nutritional status of the soil.     

Treatment of leachate from the anaerobic fermentation of solid wastes using two biofilm support media.

Biofilms growing on different carrier media have a different response to the nutrients contained in wastewater. Biofilms have proven to be an alternative to the treatment of wastewater containing higher concentrations of contaminants. The main objective of this research was to compare two biofilm support media for the treatment of leachate from the anaerobic fermentation of solid wastes. The removal of organic matter and ammonia was achieved in two fixed bed biofilm reactors containing Kaldnes and Linpor support materials with specific surface areas of 490 and 270 m2/m3, respectively, and operating under the sequencing batch procedure during 204 days. The Linpor reactor achieved higher total COD removal than the Kaldnes reactor (47% and 39%, respectively). Linpor was shown to be less sensitive to influent COD changes than Kaldnes. The effluent total COD values of Kaldnes were higher than Linpor. The dissolved COD removal was 21% for both reactors. The average ammonia removal for Linpor was 72% and 42% for Kaldnes. The matrix of Linpor allows higher concentrations of microorganisms (as dry mass) than Kaldnes. The dry mass concentration was related to the "active" exposed surface area of the biofilm. This is considered to be the cause for the better performance of Linpor when compared with Kaldnes.     

Experimental study of a novel hybrid constructed wetland for water reuse and its application in Southern China

A new type of hybrid constructed wetland (CW), consisting of both vertical-baffled flow wetland (VBFW) and horizontal subsurface flow wetland (HSFW), has been deployed in Southern China to naturally accelerate the removal of organic matter and nitrogen. The hybrid CW system is characterised by a combination of continuous baffled flow vertical wetland and 'S' pattern horizontal subsurface flow wetland with natural aeration ditches to increase the concentration of dissolved oxygen in the HSFW bed. An internal circulatory system from the HSFW effluent back to the VBFW may optionally be operated to enhance the biological denitrification effect. Cyperus alternifolius is the main macrophyte in the wetland bed. The performance of the hybrid CW was studied with a pilot-scale system and three full-scale systems for municipal sewage treatment in Southern China. The results suggest that this new hybrid CW can achieve removal efficiencies of chemical oxygen demand, suspended solids, ammonia nitrogen, total nitrogen, and total phosphorus of better than 83.6, 95.0, 71.7, 64.5 and 68.1% respectively, with a specific wetland bed area of 0.70-0.93 m(2) PE(-1). The mean effluent concentrations of these parameters would meet the regulatory discharge limits for wastewater treatment systems (GB18918, 2002) and reuse in the context of agricultural irrigation solutions in China.     

分散式生活污水处理工艺:DASB+W-SFCW联合工艺

提出了“DASB+W-SFCW”联合工艺,并运用该工艺对分散式生活污水进行了处理试验研究。DASB单元采用短时厌氧技术,去除颗粒有机物和部分溶解有机物,防止W-SFCW堵塞,保证W-SFCW单元脱氮所需的碳源。W-SFCW床优化了传统潜流人工湿地的水流流态,使污水在W-SFCW床内呈波式流动,充分地发挥了湿地系统降解污染物的能力。试验结果表明:“DASB+W-SFCW”联合工艺对生活污水具有较强的处理能力,当进水中COD,NH3-N,TP的平均质量浓度分别为268 mg/L,31.5 mg/L,5.5 mg/L时,其平均去除率分别达到80.7%,52.1%,89.7%,出水水质优于传统的二级生物处理工艺。     

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.     

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.     

不同填料强化生态浮床对淡水养殖水体的净化效果

人工填料强化生态浮床是近年来发展起来的一种新兴生态工程修复技术。选取3种不同类型的人工填料与挺水植物组合,分析其对高磷浓度养殖水体和上海市养殖池塘水体的净化效果。结果表明,在高磷浓度(2.36~3.42 mg/L)养殖水体中,人工填料强化生态浮床对TN、TP、COD的平均去除率分别为34.9%,12.2%,26.1%,且3组系统之间差异不明显。在上海市养殖水体平均浓度条件下,3组系统对TN和TP的去除能力为:立体弹性填料强化生态浮床＞组合填料强化生态浮床＞生物绳填料强化生态浮床,立体弹性填料强化生态浮床对TN和TP的去除率分别为83.9%和69.3%;3组系统对COD和NH₄⁺-N的去除率均在70%以上。因此,立体弹性填料强化生态浮床可以考虑应用于上海市淡水养殖池塘水体的生态修复工程。     

Use of real-time PCR to examine the relationship between ammonia oxidizing bacterial populations and nitrogen removal efficiency in a small decentralized treatment system 'Johkasou'.

The aim of this study was to examine the relationship between ammonia oxidizing bacterial populations and biological nitrogen removal in a small on-site domestic wastewater treatment system "Johkasou". The population dynamics of ammonia oxidizing bacteria (AOB) in six full-scale advanced Johkasous was surveyed using real-time PCR assay over a period of one year. These Johkasous were selected to compare the AOB populations in different treatment performance. When the effluent NH4-N concentration was higher than 2 mg L(-1), it was difficult to meet the effluent standard of advanced Johkasous (T-N 10 mg L(-1)). In contrast, the nitrogen removal efficiency was hardly affected by nitrite oxidation and denitrification in these systems. In other words, ammonia oxidation was a rate-limiting step. Furthermore, we focused on the relationship between NH4-N loading per AOB cell and nitrogen removal. Real time PCR monitoring results demonstrated that it is important to regulate NH4-N loading per AOB cell below 210 pg cell(-1) day(-1) to meet the effluent standard of advanced Johkasou. It is considered that NH4-N loading per AOB cell is a useful parameter for determining suitable nitrogen loading and small decentralized system design.     

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.     

不同植物配置人工湿地冬季生活污水净化效果比较

以某三级串联水平潜流人工湿地污水处理工程为实验基地,研究了5种华南地区常见湿地植物的选择和配置对净化冬季生活污水的影响,为华南地区人工湿地合理优化配置植物提供一定的依据。结果表明:人工湿地系统在冬季对COD、BOD5、TP和大肠菌群仍有较好的去除效果,对TN的去除效果较差。在实验条件下,COD和BOD5的降解主要发生在第一级湿地单元,TP和TN的降解主要发生在第三级湿地单元。三级串联湿地系统净化效果较佳的植物搭配是:第一级栽种水生美人蕉,第二级栽种再力花,第三级栽种菖蒲。     

深度处理维生素制药废水的中试研究

维生素制药废水经过初步生化处理后,出水水质无法满足要求,具有难降解、COD和氨氮浓度高的特点,针对这些特点,本文采用"强化复合曝气水解酸化→高效厌氧复合反应→流离生物接触氧化"连续工艺深度处理维生素制药废水,研究其可行性。处理规模为7.2 m3/d的中型试验结果表明:强化复合曝气水解酸化能使进水B/C值由0.33提高到0.48,提高下一步生化反应的处理效率,当进水CODCr的浓度为150～641 mg/L,氨氮浓度为6～115 mg/L时,平均去除率分别达到84.28%、93.8%,出水COD浓度小于50mg/L,氨氮浓度小于5 mg/L,出水水质能够达到《城镇污水处理厂污染物排放标准》GB18918-2002中的一级A指标,该连续工艺深度处理此类废水具有可行性和稳定性。