浅谈人工湿地组成及处理污水机理

人工湿地系统处理污水有显著的优点:氮磷去除能力强,投资低,处理效果好,操作简单,维护和运行费用低.以其为基础的生态技术费用低廉,实用有效,适合在我国推广应用.     

人工湿地技术的应用及展望

本文在阅读大量文献的基础上,就人工湿地污水处理系统的发展历史、研究进展和去污机理等进行了综述,并对该技术在我国的应用和发展进行了展望,为该技术的应用和发展打下基础。     

巨野县人工湿地水质净化工程治理措施

本文分析了巨野县人工湿地水质净化工程的基本情况,污染状况,水质净化工程治理方案,有针对性地提出改善区域生态环境的对策。     

人工湿地处理农村生活污水综述

结合我国农村生活污水的特点和处理现状,分析了人工湿地的去污机理,总结了其优点和目前运行中存在的问题,并介绍了人工湿地技术在国内外农村应用的情况。指出人工湿地作为一种在国外广泛成功应用的水处理工艺,在处理我国农村生活污水方面具有广阔的应用前景和很强的推广意义。     

组合人工湿地污水处理系统研究

人工湿地系统是一个综合性的生态系统，具有缓冲容量大、处理效果好。一般可达到二级和高级水平。它应用生态系统中物种共生、物质循环再生原理，结构与功能相关原则。在促进水中污染物质良险循环的前提下充分发挥资源的生产潜力，防止环境的再污染。获得污水处理与资源化的最佳效益。     

人工湿地处理生活小区污水可行性分析

目前人工湿地处理城市生活污水特别是生活小区污水处理倍受关注.本文阐述了人工湿地的含义、类型及净化机理,并对人工湿地应用于小区污水处理进行了详细的可行性分析     

浅谈人工湿地处理垃圾渗滤液的应用

论述了人工湿地处理垃圾渗滤液的国内外处理现状、特点、机制,包括有机物、氨、重金属、藻类、悬浮物的去除机理。提出了人工湿地处理垃圾渗滤液目前存在的问题,并对今后的研究做出了展望。     

基于GA－BP网络的人工湿地污水净化效果研究

人工湿地作为污水处理领域的一种新型生态技术,逐渐得到应用并倍受关注。人工湿地污水净化过 程呈多参数影响的复杂非线性状态,采用传统的数学方法难以建立准确的数学模型并进行多因素分析,也无法 精确定出湿地系统最佳运行工况。基于大量可靠的试验数据,首次采用遗传神经网络方法模拟湿地除污系统, 详细论述了网络拓扑结构优化和训练数据预处理等关键问题,建立了可靠的GA－BP模型,并采用该模型仿真湿 地系统正交试验,依据正交试验结果对影响因素进行分级,确定了最佳运行工况,并在此基础上有针对性地提 出可行的强化除污措施。     

人工湿地污水处理技术研究进展

在目前的状况下,污水处理技术已经能够运用于人工湿地工程,从而达到净化人工湿地的目标。因此该文结合污水处理领域的主要处理手段,通过分析污水处理技术运用于人工湿地净化的必要性,从而给出当前研究人工湿地污水处理技术的具体进展情况。     

人工湿地植物景观浅析

人工湿地近年来越来越受关注,但是从园林景观方面探寻人工湿地植物景观的研究却相对较少。在人工湿地定义的基础之上,从园林设计角度来探讨人工湿地植物景观,同时浅议人工湿地植物景观的系列设计要点,包括人工湿地植物的筛选原则、人工湿地植物景观的造景原则以及人工湿地植物的群落构成三方面,试图以此来探寻一种用以营造生态的、优美的人工湿地植物景观的园林理论。     

The use of constructed wetland for dye-rich textile wastewater treatment

The objective of the present paper was to examine the treatment efficiency of constructed wetlands (CW) for the dye-rich textile wastewater with special focus on colour reduction. Preliminary, a series of dynamic experiments was performed in the CW model packed with gravel, sand, and zeolitic tuff on three synthetically prepared wastewaters using chemically differ dyestuffs, auxiliaries and chemicals, in order to investigate the potential of low-cost materials as media for textile dye-bath wastewater treatment. The obtained results evidence that applied CW model reduces colour by up to 70%, and COD and TOC by up to 45%. Based on these results, the pilot CW with vertical (VF) and horizontal flow (HF) was constructed near textile factory mainly for cotton and cotton/PES processing with intention to treat real textile wastewater in situ. It was designed for 1 m³/day, covering 80 m², packed with sand and gravel, and planted with Phragmites australis. The average treatment efficiency of the CW for the selected pollution parameters were: COD 84%, BOD₅ 66%, TOC 89%, N_total 52%, N_organic 87%, NH₄-N −331%, sulphate 88%, anion surfactant 80%, total suspended solids (TSS) 93%, and colour 90%, respectively. The results unequivocally proved that the CW could offer an optimal solution to meet the environmental legislation as well as requirements for effective and inexpensive textile wastewater treatment.     

Evaluation of small-scale constructed wetland for water quality and Hg transformation

Elevated concentrations of nutrients and mercury (Hg) make Steamboat Creek (SBC) the most polluted tributary of the Truckee River. Since wetlands are considered cost-effective, reliable, and potential sites for methylmercury (MeHg) production, a small-scale wetland system was constructed and monitored for several years in order to quantify both nutrient removal and transformation of mercury. Results indicated seasonal variations in nutrient removal with 40-75% of total nitrogen and 30-60% of total phosphorus being removed with highest removals during summer and lowest removals during winter. The wetland system behaved as a sink for MeHg during the winter months and as a source for MeHg during summer months.     

A pilot study on wastewater treatment by constructed wetlands with high dissolved oxygen vegetated submerged bed

It is necessary to treat wastewater in a more environmentally friendly fashion, vegetated submerge bed constructed wetlands (CWs) has become the focus of the research in this field. In this paper, the overall capacity of vertical subsurface flow CWs in the removal of pollutants from municipal wastewater effluent and the effects of the depth of vegetated submerged bed on the removal efficiency were studied. The results showed that the COD, NH4+-N and TN could be removed effectively in the vertical subsurface flow CWs, the best efficiency was obtained from the 10 cm run. However, the TP removal was not effective in all vertical CWs. A shallow depth of vegetated submerged bed may avoid the risk of substrate plugging effectively, and may keep a stable operation of CWs in long term. Decreasing the depth of vegetated submerged bed could create a sufficient aerobic circumstance in which the concentration of DO in bed was super saturation.     

Distribution of extractable fractions of heavy metals in sludge during the wastewater treatment process

Sludge samples were collected from different treatment steps of Gaobeidian wastewater treatment plant (WWTP) of Beijing City, PR China, to investigate the distributions of total and chemical fractions of Fe, Mn, Ni, Cu, Zn, Cr, Pb, and Mo in different sludges. The highest total concentrations were found for Fe, Mn, Pb, and Mo in digested sludge (DS), Ni and Cr in thickened sludge (TS), Zn in dewatering sludge (DWS), and Cu in active sludge (AS). The lowest concentrations were observed in AS, except for Cu in TS. Significant differences of total metal concentration were observed between AS and TS (or DS), suggesting that sludge thickening and digesting treatments significantly influenced the total metal concentrations. Fe, Cu, Ni, Cr, Mo, and Pb distributed principally in the residual fraction in all sludges, while Zn and Mn presented in a highly available fraction. For same metal in different sludges, the portion of easily mobile fraction decreased significantly along the wastewater treatment process, and metals in AS presented in the highest available fraction. Organic matter contents, TN, and TP of sludges exhibited a significant positive correlation with the concentrations of exchangeable and reducible fraction of Pb, Mo, Cr, Cu, and Fe, while sludge pH demonstrated significant negative correlations with the concentrations of these metals.     

Optimal choice of wastewater treatment train by multi-objective optimization

The typical domestic wastewater treatment train consists of some combination of unit operations for preliminary, primary, secondary, tertiary, and advanced treatment, and residual management, with many options being available for each type of unit operation. The challenge is to select treatment trains for which the extent and reliability of treatment are high, whereas the capital, operation and maintenance (O&M) costs of the treatment and land area requirement are low. This proposition has been formulated as a multi-objective optimization problem, and solved using the evolutionary/genetic optimization technique. The inputs required are the capital costs, O&M costs, land area requirements, and reliabilities of the unit operations of various types. In addition, overall environmental cost (E) corresponding to various treatment trains is input as a normalized parameter, which can take values in the range 0–100, with E being 100 corresponding to the ‘no treatment’ option. In other cases, E is a function of both treatment train efficiency and reliability. The problem was solved to determine the Pareto optimal, i.e. ‘no worse’ than each other, set of solutions under three conditions, viz. when E was not constrained, and for E<75, and E<50. Correctness of the algorithm was probed through a threefold analysis, (1) by solving a simplified two-objective problem, (2) by demonstrating the efficiency of the algorithm in picking up ‘sure-optimal’ solutions, i.e. solutions deliberately made optimal through manipulation of input data, and (3) by demonstrating that the set of optimal solutions remains approximately the same irrespective of the variations in the initial population size chosen for the genetic operations.     

Experimental research on heavy metal wastewater treatment with dipropyl dithiophosphate

In view of the existing technical problems about treatment of heavy metal pollution, a new organic heavy metal chelator-dipropyl dithiophosphate has been developed. This paper focuses on the mechanism about the laboratory synthesis of dipropyl dithiophosphate and chelate heavy metal, discusses the effects of pH value, added quantity of chelator, reactive time and coexistence of several heavy metal ions on the treatment effectiveness, and compares the stability of chelate complex with conventional neutral precipitation method. The results of the experiment show that, within the scope of pH 3-6, for the wastewater with the concentration of lead, cadmium, copper and mercury being 200 mg/L, dipropyl dithiophosphate enjoys a removal rate about these elements up to over 99.9%, and the concentrations of the lead, cadmium, copper and mercury in the wastewater after treatment are less than 1, 0.1, 0.5 and 0.05 mg/L, respectively, which meet the limit value of concentration stipulated in the Integrated Wastewater Discharge Standard (GB8978-1996). And the treatment effectiveness are not affected by pH value and coexistent heavy metal ions, which makes up the deficiency that neutral precipitation must be used under the condition of high alkalinity. The optimum quantity of dipropyl dithiophosphate chelator added is 1.2 times as much as stoichiometric amount and the optimum reactive time is 20 min for lead, cadmium and copper, and 30 min for mercury. Within the scope of pH 3-9, each heavy metal ion release of chelate complex will decrease along with increased pH value. But under any pH conditions, the release of heavy metal ions in hydroxide is far higher than that in chelate complex, therefore reducing the risk of polluting the environment again.     

Use of adsorption process to remove organic mercury thimerosal from industrial process wastewater

Carbon adsorption process is tested for removal of high concentration of organic mercury (thimerosal) from industrial process wastewater, in batch and continuously flow through column systems. The organic mercury concentration in the process wastewater is about 1123 mg/L due to the thimerosal compound. Four commercially available adsorbents are tested for mercury removal and they are: Calgon F-400 granular activated carbon (GAC), CB II GAC, Mersorb GAC and an ion-exchange resin Amberlite GT73. The adsorption capacity of each adsorbent is described by the Freundlich isotherm model at pH 3.0, 9.5 and 11.0 in batch isotherm experiments. Acidic pH was favorable for thimerosal adsorption onto the GACs. Columns-in-series experiments are conducted with 30-180 min empty bed contact times (EBCTs). Mercury breakthrough of 30 mg/L occurred after about 47 h (96 Bed Volume Fed (BVF)) of operation, and 97 h (197 BVF) with 120 min EBCT and 180 min EBCT, respectively. Most of the mercury removal is attributed to the 1st adsorbent column. Increase in contact time by additional adsorbent columns did not lower the effluent mercury concentration below 30 mg/L. However, at a lower influent wastewater pH 3, the mercury effluent concentration decreased to less than 7 mg/L for up to 90 h of column operation (183 BVF).     

Combined electrocoagulation and TiO(2) photoassisted treatment applied to wastewater effluents from pharmaceutical and cosmetic industries

The treated wastewater consists of refractory materials and high organic content of hydrolyzed peptone residues from pharmaceutical factory. The combination of electrocoagulation (EC) followed by heterogeneous photocatalysis (TiO(2)) conditions was maximized. The EC: iron cathode/anode (12.50 cmx2.50 cmx0.10 cm), current density 763Am(-2), 90min and initial pH 6.0. As EC consequence, the majority of the dissolved organic and suspended material was removed (about 91% and 86% of the turbidity and chemical oxygen demand (COD), respectively). After EC, refractory residues still remained in the effluent. The subsequent photocatalysis: UV/TiO(2)/H(2)O(2) (mercury lamps), pH 3.0, 4h irradiation, 0.25gL(-1) TiO(2) and 10mmolL(-1) H(2)O(2) shows high levels of inorganic and organic compounds eliminations. The obtained COD values: 1753mgL(-1) for the sample from the factory, 160mgL(-1) after EC and 50mgL(-1) after EC/photocatalyzed effluents pointed out that the combined treatment stresses this water purification.     

Treatment of printed circuit board industrial wastewater by Ferrite process combined with Fenton method

Printed circuit board wastewater typically contains organics and metal ions. The study explored the feasibility of a sequential procedure, FFP (the combination of the Fenton method and the Ferrite process), for treating printed circuit board wastewater, and established the optimum parameters for it. The analytical results showed that the proper pH level was 2 for Fenton oxidation, and the appropriate H₂O₂ dosing type was batch dosing. For the Ferrite process, the suitable Fe/M (Fe is the total dose of Fe²⁺ added to a solution and M is the initial total moles of various metal ions in untreated wastewater) molar ratio was 10 and the sludge met the toxicity characteristic leaching procedure (TCLP) standards. Following FFP treatment, effluent water or sludge easily met Taiwan's standards. Finally, the SEM/EDS test demonstrated that particle sizes of the sludge were approximately 50–80 nm, and the saturation magnetization was 67.5 emu/g.     

Electrolytic treatment of Standard Malaysian Rubber process wastewater

A new method of Standard Malaysian Rubber (SMR) process wastewater treatment was developed based on in situ hypochlorous acid generation. The hypochlorous acid was generated in an undivided electrolytic cell consisting of two sets of graphite as anode and stainless sheets as cathode. The generated hypochlorous acid served as an oxidizing agent to destroy the organic matter present in the SMR wastewater. For an influent COD concentration of 2960 mg/L at an initial pH 4.5+/-0.1, current density 74.5 mA/cm(2), sodium chloride content 3% and electrolysis period of 75 min, resulted in the following residual values pH 7.5, COD 87 mg/L, BOD(5) 60 mg/L, TOC 65 mg/L, total chlorine 146 mg/L, turbidity 7 NTU and temperature 48 degrees C, respectively. In the case of 2% sodium chloride as an electrolyte for the above said operating condition resulted in the following values namely: pH 7.2, COD 165 mg/L, BOD(5) 105 mg/L, TOC 120 mg/L, total chlorine 120 mg/L, turbidity 27 NTU and temperature 53 degrees C, respectively. The energy requirement were found to be 30 and 46 Wh/L, while treating 24 L of SMR wastewater at 2 and 3% sodium chloride concentration at a current density 74.5 mA/cm(2). The observed energy difference was due to the improved conductivity at high sodium chloride content.