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目 录两种活性污泥处理系统处理焦化废水的效果比较1摘要11.引言22. 材料和方法43结果54结论8COKE OVEN WASTEWATER TREATMENT BY TWO ACTIVATED SLUDG SYSTEMS9ABSTRACT91.INTRODUCTION112. MATERIALS AND METHODS133. RESULTS144. CONCLUSIONS17REFERENCES1819两种活性污泥处理系统处理焦化废水的效果比较 C.A. PAPADIMITRIOUX. DABOUP. SAMARASG.P. SAKELLAROPOULOS摘 要在这项研究中，使用了两种活性污泥处理系统CSTR工艺和SBR工艺来处理焦化废水，其曝气池均为狭长的条形池。这两种污泥处理系统反应器使用的活性污泥都接种自城市污水水处理厂。在操作流程的第一个反应阶段，将城市污水和合成废水混合后进水，流入反应池中。让污泥中的微生物完全适应合成废水，这大约需要60天左右。反应池中的操作可分为三个不同的阶段。第一个阶段，主要是处理含有高浓度的有机物但是不含有毒物质的合成废水。在这段时期内，两个污泥处理系统反应池中的COD和BOD5的去除效率可分别达到95和98。在SBR反应器中，营养物质的去除效率，比CSTR反应器中的效率更高。在第二个阶段，添加进入反应池的酚的浓度高达300mg/L。酚被加入反应池之后，大约过了20天便开始降解。在这段时期内，没有观察到添加的酚对营养物去除效率有什么影响，但是，两个污泥处理系统反应池中的有机物质的去除效率都略微降低了。在第三个阶段，酚在水体中的浓度逐渐增加，高达1000mg/L，与此同时，加入到混合水体中的氰化物和硫氰化物的浓度分别达到20mg/L和250mg/L。这个时期的混合水体，是和焦化废水完全一样的。添加进入反应池的酚和氰化物的浓度持续增加，使得CSTR反应池中的活性污泥微生物发生不可逆转的反应，与此同时，SBR工艺在抵抗和降解有毒化合物方面，显示出了更强的的能力。这个时期的开始，其显著特征是活性污泥中悬浮固体的稳定性降低，并且伴随着有机物质和营养物质的去除效率下降。这段时期，水体特征的监测报告的结果显示，在SBR反应池中去除了90的有机负荷、85的营养物质和超过90的苯酚和氰化物，然而，在CSTR反应池中的去除效率分别只有75、65和80。关键词：SBR CSTR 酚 氰化物 焦炉 活性污泥1. 引 言在当今，生物废水处理系统被用来处理含有难以降解和有毒化合物的工业废水。和一般的工业废水不同的是，焦化厂的废水包含有氨、氰化物、硫氰化物和许多有毒的有机污染物，例如酚类、单环和多环含氮化合物和多环芳烃类。由于这些混合物的存在，所以限制了生物系统对这种废水的处理。历史上，关于焦化废水的处理，起源于70年代的中国，最早建设了传统活性污泥处理的单元设备。然而从这些设备中出来的、处理过的废水并不符合国际排放标准。为了解决这个问题，和发现最适合的处理技术，现在大量的调查都投入到这种特种废水中的研究中。Lim报告说，生物处理过程结合Fenton氧化作用，焦化废水也许能够得到有效处理。不过，这种方法有一定的缺陷，为了减少操作成本，焦化废水在处理之前必须要用海水稀释过。然而，增加的盐分有可能会对活性污泥的沉淀和分解产生不利的影响，而且可能会降低活性污泥微生物的存活数量。Ghose提出了一种物理化学处理模式，通过在二次沉砂池中加入石灰浆来处理焦化厂废水，同时，通过人造沸石圆柱，可以有效的实现氮的去除。此外，在真空过滤之前，必须加入化学药品，用以改善污泥的脱水特性。另一方面，结合使用生物铁活性污泥处理，强化污泥的絮凝情况，用来有效低去除酚类、氰化物和BOD5。这样，通过生物氧化和生物絮凝的结合过程，活性污泥可以得到净化，为了提高去除效率，这两个过程都必须外加深度处理。污泥中的微生物的质量和生理学状态是最重要的因素。Suschka正在集中研究含酚焦炭的焦化废物的处理，其侧重点在于不稳定的情况下，废水的处理。不稳定性主要和废水的水质特征有关。其他的一些研究把重心放在特殊化合物的行为特性和生物降解上，主要是关于奎宁、氰化物和含氮物质等等。在最近的研究中，焦化厂的废水的处理在厌氧厌氧好氧生物膜系统和厌氧好样生物膜系统中进行，结果显示，第一种结构系统比第二种能够更好的去除氮。为了提高整个降解过程的稳定性，构建了一个两步生物处理步骤的方法，包括一个活性污泥处理单元，以及处理单元后的硝化作用反应器。然而，仍然没有有力的证据表明，有一种成功的处理焦化废水的方法，能够使得有机的和无机的污染物都得到有效的去除。在用来处理工业废水的生物系统中，比较有效率的是序批式活性污泥法处理系统（SBR）。在SBR系统中的进行的反应步骤和单元操作，和在传统活性污泥中反应和操作相似。不同的是，SBR系统的所有后续阶段都在一个独立的容器中进行。由此对空间的需要被减少到最小，除了这一长远的好处之外，还克服了和这个结构有关的其他的缺陷。所以，SBR系统能够解决那些一般是由其他技术处理的各种不同类型的废水。这个系统的研发源于50年代后期这段时间。自从那以后，为了评估这个系统的效用和效率，又做了好几项研究调查。虽然序批式活性污泥法处理系统（SBR）最初是用来去除COD的，但研究显示在这些系统中，氮化合反应过程进行得非常顺利。其他研究的开展主要是侧重于SBR系统对营养物质的去除效率，使处理过的废水能够符合严格的废水排放标准。Umble和Ketchum用SBR系统来去除城市污水的生物营养物质，在每12小时一个循环的周期中，被去除的BOD5、TSS和NH3-N分别减少了98、90和95。在这个研究计划中，关于焦化废水的治理，要监测这两种不同的系统：传统生物处理的单元系统和序批式活性污泥法处理系统。2. 材料和方法（1）廊道式条形反应池在这项研究中用了两种廊道式条形反应池，图1a和图1b分别展示了一个连续流活性污泥系统反应池和一个序批式活性污泥系统反应池相应的流程图。活性污泥反应池中的菌种从Thessaloniki的城市污水处理厂接种获得。每个反应单元加入大约2升的活性污泥，最初的阶段用城市污水培养大约3个星期。高浓度的合成废水逐量的添加到反应池单元系统中，这一过程的适应期需要超过两个月。在这项研究中，用合成废水来模拟焦化废水。合成废水用下列分析标准物质来准备：833mg/L的葡萄糖（PANREAC），2000mg/L的醋酸钠（J.T.Baker），100mg/L的N氯化钠（J.T.Baker），50mg/L的 二水合氯化钙（J.T.Baker），20mg/L的氯化钾（J.T.Baker），600mg/L的氯化铵（J.T.Baker）和333mg/L的三水合磷酸氢二钾（J.T.Baker）。其他成分例如，酚、硫氰化物和氰化物的浓度分别高达800mg/L、200mg/L和100mg/L。（2）物理和化学的监测被监测到的BOD5，混合液悬浮固体（MLSS），悬浮固体（SS），NO3，NH4+，NO2,COD,酚和氰化物和甲基苯乙烯一致。 Figure 1. Flow diagrams of the continuous bench scale activated sludge reactor (A) and the sequential batch reactor (B) 3结 果在这两种反应器中，用各种成分的流入和流出浓度做为操作时间的一个应变函数，正如图1a-f所示。在活性污泥微生物适应了人造焦化基质之后，对两个系统开始监测。流入水流中所含的酚的范围从700到1200mg/L，同时相应的去除效率超过99，在SBR系统单元中，监测指示流入水流的完全降解，流出水流所含的酚的值在1.0到4.6mg/L之间。然而，流入水流中增加的酚含量达到800mg/L，CSTR反应池的运作就会受到影响，导致下列的操作问题：1. 有机负荷的去除能力降低（BOD、COD）。 2. 氮化合反应的效率降低。 3. 限制酚的降解，导致流出水流中的酚的浓度范围在10到60mg/L之间。 4. 絮凝能力的降低。研究证明，SBR系统中活性污泥微生物被比相应的CSTR系统中的微生物，对各种流入水流中的酚的含量有更强的抵制能力，并且呈现出更高的恢复速率和短时间内有效操作的重新建立。水流中增加的酚可能影响这两种系统的有机物质的去除效率。这两个反应池中的流入水流中的COD的含量和相应的流出水流的含量，做为操作时间的一个应变参数呈现在图2b中，同时相应的BOD5的值显示在图2e中。含有高浓度的酚的流入水流，进入对SBR反应池，没有造成影响，处理后为高质量的流出水流：COD的浓度值在270到550mg/L之间（图2b），相应的COD的去除效率在87到95之间，与此同时，流出水流中的BOD5的浓度值在60到152mg/L之间，相应的去除效率在95%到98之间。然而，增加的酚的极大的影响了CSTR系统中的运作：在CSTR系统中的流出水流监测到了比较高的COD值，其范围295到1500mg/L之间，COD的去除效率约在67到93之间，表现得比较差。除此之外，CSTR系统的流出水流的BOD5的浓度含量在150到500mg/L之间变化，导致BOD5的去除效率在82.5到95之间。CSTR系统中流出水流的质量的下降，和酚对活性污泥中特定种类微生物的产生潜在毒性作用有关联。 Figure 2 Influent and effluent concentration of a) MLSS, b) COD, c) N NH4, d) SS, e) BOD5,f) phenol, as function of operation time, in the bench scale activated sludge reactors两个反应池的流入水流和流出水流的NH4-N浓度都呈现在图2c中，做为操作时间的应变参数。在SBR反应池中，流出水流的NH4-N的浓度在2到23mg/L之间变化，相应的去除率93到99之间。在CSTR系统单元中观察到更高的水流值，在25到91mg/L之间变化，相应的去除效率在83到95之间。硝化过程例如氨氧化成硝酸盐，不受添加的酚的影响，同时在延长的操作时间里，SBR系统和CSTR系统相比，其运作显得更有效率，因此流出水流的氨值更低。这两种系统中的流出水流的悬浮固体浓度做为操作时间的应变参数显示在图2d中。在CSTR系统单元中，流出水流的SS含量超过流入水流中苯酚的浓度，其含量高达500mg/L，同时相应在SBR系统中的数值维持在100mg/L以下。两个廊道式条形反应池中流入水流和流出水流中的氰化物浓度的变化显示在图3中，做为操作时间的应变参数。在这段时期内，流入水流中的氰化物浓度在70到270mg/L中间变化，SBR系统中流出水流的浓度范围在1.1和2.8mg/L之间，相应的去除效率约为97到99，指示出氰化物几乎完全去除。然而，在CSTR系统单元中观察到了更高的流出浓度，高达36mg/L，去除效率在76到99之间。SBR系统单元的活性污泥微生物很好的适应了添加的氰化物，使得去除得到强化。立法机构关于氰化物的规定措施是非常严格的，规定流出水流低于1mg/L（Morper and Jell，2000）。Figure 3 Influent and effluent cyanide concentration as function of operation time, in the bench scale activated sludge reactors这两种系统中在曝气池中的微生物浓度做为操作时间的应变参数在图2a中。MLSS的含量在SBR系统中在4600到6000mg/L之间变化，在CSTR系统中在2100到5300mg/L之间变化。在SBR系统中，附加的酚和氰化物对微生物浓度有轻微的影响，然而，在CSTR单元中由于这些化合物对活性污泥微生物的潜在毒性作用，观察到了非常显著的影响，除此之外，CSTR活性污泥微生物更加敏感，在毒性的冲击下无法复原。在这些情况之下，活性污泥里含有的丝状微生物的稳定特质显很差。4结 论归结起来，在酚和氰化物的浓度不断增加的情况下研究斜体式活性污泥反应器的操作。进水水流中高达1200mg/L的酚的浓度，在SBR系统中几乎能够完全降解，与此同时，用COD、BOD5和氨氮表示的有机物质的去除，并没有因为增长的酚的负荷，而表现出被明显的抑制。在氰化物添加的过程当中,SBR系统单元保持这中有效率的操作，高浓度的氰化物去除率超过97。然而，增加的酚影响了CSTR系统单元的操作，导致低质量的流出水流中含有高浓度的有机物质（BOD5超过150mg/L,COD超过300mg/L）。Global NEST Journal, Vol 8, No 1, pp 16-22, 2006Copyright 2006 Global NESTPrinted in Greece. All rights reservedCOKE OVEN WASTEWATER TREATMENT BY TWO ACTIVATED SLUDGE SYSTEMSC.A. PAPADIMITRIOU1* 1 Chemical Process Engineering Research InstituteX. DABOU1 and Department of Chemical EngineeringP. SAMARAS2 Aristotle University of ThessalonikiG.P. SAKELLAROPOULOS1 PO Box 1520, 54006, Thessaloniki2 TEI of West MacedoniaDepartment of Pollution Control TechnologiesKoila, 50100, KozaniSelected from papers presented in 9thInternational Conference on EnvironmentalScience and Technology (9CEST2005)1-3 September 2005, Rhodes island, Greece*to whom all correspondence should be addressede-mail: papadimcperi.certh.grABSTRACTIn this study two bench scale activated sludge systems were used, a CSTR and an SBR for the treatment of coke oven wastewater. Both reactors were inoculated with activated sludge from a municipal wastewater treatment plant. At the first stages of operation, reactors were feed by a mixture of municipal wastewater and synthetic wastewater. Full acclimatization of the microorganisms to synthetic wastewater was achieved in 60 days. The operation of the reactors was divided into three distinct periods. The first period was characterized by the treatment of high organic but non-toxic synthetic wastewater. During this period COD and BOD5 removal efficiencies reached 95 and 98% respectively, in both reactors. Nutrient removal was better in the SBR reactor rather than in the CSTR. In the second period phenol was added in concentrations up to 300 mg /L-1. Degradation of phenol started about the 20th day after its introduction to the reactors. In this period no effects of phenol to nutrient removal were observed, whereas the removal efficiency of organic matter in both reactors was slightly decreased. During the third period phenol concentrations of the influent were gradually increased to 1000 mg/L-1, while cyanide and thiocyanite were added to the influent composition to concentrations reaching concentrations of 20 and 250 mg /L-1respectively. The composition of the influent of this period was a full assimilation of coke oven wastewater. Introduction of increased phenol concentrations along with cyanide compounds initiated irreversible effects on the activated sludge microfauna of the CSTR causing inherent problems to the treatment process, while SBR showed greater capacity to withstand and degrade toxic compounds. The beginning of this period was characterized by decreased settleability of the suspended solids as well as decrease of organic matter and nutrient removal efficiencies. Monitoring of the effluent characteristics during this period reported over 90% for organic load, 85% of nutrient removal and over 90% of phenol and cyanide removal in SBR, while the removal efficiencies for the CSTR were 75, 65 and 80% respectively.KEYWORDS: SBR, CSTR, phenol, cyanide, coke oven, activated sludge1. INTRODUCTIONBiological wastewater treatment systems are currently used for the treatment of industrial effluents containing persistent and toxic compounds. However, coke-plant wastewaters contain ammonia, cyanide, thiocyanate, and many toxic organic contaminants such as phenols mono and polycyclic nitrogen containing compounds and PAHs 1,2. As a result, these compounds limit the application of a biological process for the treatment of such effluents. Historically, the concern on the treatment of coke oven wastewaters started at 70s in China, where conventional activated sludge units were constructed. However the treated effluent from these units did not comply with the national discharge standards 3. As a result a considerable amount of research is currently focusing on the study of the most appropriate treatment techniques of the specific wastewaters.Lim reported that wastewater from coke ovens may be effectively treated by a biological treatment process combined with Fentons oxidation. However this approach had the disadvantage that the wastewater should be diluted by seawater prior to treatment, in order to reduce the operation costs 4. However, the increased salinity may adversely affect the processes of sedimentation and dissolution of the activated sludge, and may decrease the survival of the activated sludge microorganisms 5. Ghose suggested a physicochemical mode of treatment for coke plant effluents by the addition of lime slurry in a secondary sedimentation tank, while efficient ammonia removal might be achieved by synthetic zeolite columns 3. Furthermore, chemicals have to be added in order to improve sludge dewatering characteristics before vacuum filtration. On the other hand, the combined use of bioferricactivated sludge processes offered enhanced coagulation performance that efficiently removed phenols, cyanide and BOD5 6. In this way, activated sludge may be purified through the combined process of bioxidation and bioflocculation; both processes have to be intensified in order to improve the removal efficiency. The most important variable was the quality and physiological status of the microorganisms. Suschka was focusing at the treatment of phenolic coke coking wastes emphasizing the treatment under unstable conditions 1. The instability was mainly associated with the qualitative characteristics of the effluent. Some other studies were focused on behavioral characteristics and/or biodegradation of specific compounds and mainly with quinine, cyanide and nitrogen containing substances 2,7. Coke plant wastewaters were treated by an anaerobic-anoxicaerobic film system in conjunction to an anoxic- aerobic one in a recent study and it was shown that better nitrogen removal was achieved by the first configuration than the latter one 2. A two-step biological treatment method has been established consisting of an activated sludge unit followed by a nitrification reactor for the stabilization of the overall biodegradation process 8. However, there is still no clear evidence about a successful method of treating coke oven effluents, resulting in an efficient removal of both organic and inorganic pollutants. An efficient biological system, which has been used for the treatment of industrial wastewaters, is the Sequential Batch Reactor system (SBR).The processes and the unit operations taking place in an SBR system are similar to those in a conventional activated sludge. The difference is that all subsequent stages are taking place into a single tank. In addition to the profound advantage of minimization of space requirements, other advantages associated with this configuration are 9,10. As a result, SBR systems are capable of handling various types of wastewaters commonly treated by other techniques. The exploitation of such systems started during the late 50s. Since then, several studies have been performed in order to assess the usefulness and efficiency of such systems. Although Sequencing Batch Reactors were used initially for the removal of COD, the nitrification processes have been studied successfully in these systems. Other studies were presented focusing mainly on SBR efficiency to remove nutrients in order the treated effluent to comply with stringent wastewater standards. Umble and Ketchum used an SBR for biological nutrient removal of municipal wastewater; BOD5, TSS and NH3- N removals of 98, 90 and 95% respectively were alleviated in a 12h-cycle 11.In this project, two different systems will be examined for the treatment of coke oven effluents: a conventional biological treatment unit (CSTR) and a Sequential Batch Reactor system (SBR).2. MATERIALS AND METHODSBench scale reactorsTwo bench scale activated sludge reactors were used in this work, a continuous system and a Sequential Batch Reactor and the corresponding flow diagrams are shown in Figure 1a and 1b respectively. The inoculum of the activated sludge reactors was obtained from the Municipal Wastewater Treatment Plant of Thessaloniki. About 2L of activated sludge were added to the each unit and the systems were fed initially by municipal wastewater for a period of about 3 weeks. Synthetic high strength wastewater was gradually added to the reactor units over an acclimatization period of two months. Synthetic wastewater that was used in this work simulated coke oven wastewater. The synthetic wastewater was prepared using the following analytical grade substances: 833 mg /L-1glucose (PANREAC), 2000 mg /L-1sodium acetate (J.T. Baker), 100 mg /L-1 NaCl (J.T. Baker), 50 mg/L-1CaCl2 * 2H2O (J.T. Baker), 20 mg /L-1 KCl (J.T. Baker), 600 mg /L-1NH4Cl (J.T. Baker) and 333 mg /L-1 K2HPO4 *3 H2O (J.T. Baker). Additional constituents such as phenol, thiocyanide and cyanide to concentrations up to 800, 200 and 100 mg /L-1respectively.Physical and chemical monitoringBOD5, Mixed Liquor Suspended Solids (MLSS), Suspended Solids (SS), NO3, NH4, NO2, COD, phenol and cyanide were measured in accordance to APHA 12.3. RESULTSThe influent and effluent concentrations of various constituents as a function of operationtime, in both reactors, are shown in Figure 1a f. Monitoring of the two systems wasconducted after the acclimatization of the activated sludge microorganisms to the synthetic coke - oven substrate. Phenol influent content was ranging from 700 to 1200 mg /L-1, while the corresponding removal efficiencies were higher than 99%, in the SBR unit, indicating a complete degradation of influent and effluent phenol values from 1.0 to 4.6 mg /L-1. However, the increase of influent phenol content to 800 mg /L-1, affected the performance of the CSTR reactor, resulting in the following operation problems:1. Decrease in the removal capacity of the organic load (BOD, COD).2. Decrease in nitrification efficiency.3. Limited phenol degradation, resulting to effluent phenol concentrations ranging from 10 to 60 mg /L-1.4. Decrease in sedimentation capacity.SBR activated sludge microorganisms proved to be more resistant to the variation of influent phenol content than the corresponding CSTR population, presenting a high recovery rate and a short time for the re-establishment of efficient operation. The addition of phenol might affect the efficiency of both systems for the removal of organic matter. The influent COD content and the corresponding effluent values for both reactors are presented in Figure 2b as a function of operation time, while the corresponding BOD5 values are shown in Figure 2e. The introduction of high influent phenol concentration did not affect the operation of the SBR reactor, resulting in effluents of high quality: COD concentration varied from 270 to 550 mg /L-1 (Fig 2b), corresponding to COD removal efficiencies from 87 to 95%, while BOD5 effluent concentration varied from 60 to 152 mg /L-1, corresponding to removal efficiencies from 95 to 98%. However, the addition of phenol in the CSTR greatly affected its performance: higher COD values were measured in the CSTR effluent ranging from 295 to 1500 mg/L-1, indicating poor COD removal efficiencies of about 67 to 93%. In addition, BOD5 (Fig 2e) content in the CSTR effluent varied between 150 and 500 mg /L-1, resulting in BOD5 removal capacities from 82,5 to 95%.The reduced effluent quality in the CSTR system was correlated to potential toxic effects of phenol on the certain organisms of the activated sludge microfauna. reactors Influent and effluent NH4 N concentrations for both reactors are presented in Figure 2c, as a function of operation time. NH4 N effluent concentrations in the SBR reactor varied from 2 to 23 mg /L-1, corresponding to removal efficiencies from 93 to 99%. Higher effluent values were observed in the CSTR unit, varied from 25 to 91 mg /L-1, with corresponding removal efficiencies from 83 to 95%. The nitrification process i.e. the oxidation of ammonia to nitrate, was not affected by the addition of phenol, while at extended operation time, SBR showed a more efficient performance than the CSTR system, resulting in lower ammonia effluent values. The effluent suspended solids concentration in both systems, as a function of operation time is shown in Figure 2d. Effluent SS content in the CSTR unit exceeded 500 mg /L-1at high influent phenol concentration, while the corresponding values in the SBR system maintained below 100 mg /L-1. The variation of influent and effluent cyanide concentration in both bench scale reactors is shown in Figure 3, as a function of the operation time. During this period, influent cyanide concentrations varied from 70 to 270 mg /L-1; SBR effluent concentrations ranged between 1,1 and 2,8 mg /L-1 corresponding to about 97 - 99% removal efficiencies and indicating almost complete removal of cyanide compounds. However, higher effluent concentrations were observed in the CSTR unit reaching up to 36 mg/L-1, with removal efficiencies from 76 to 98. Activated sludge microfauna in the SBR unit was satisfactory acclimatized to the addition of cyanides resulting in their enhanced removal. Legislative measures for cyanides are very stringent, setting effluent lower than 1 mg /L-1 (Morper and Jell)The concentration of microorganisms in the aeration tanks of both systems as a function of operation time is shown in Figure 2a. MLSS content varied between 4600 and 6000 mg /L-1 in the SBR system and from 2100 to 5300 mg/ L-1 in the CSTR system. The addition of phenol and cyanide slightly affected the microorganisms concentration in the SBR system, while a significant effect was observed in the CSTR unit, due to potential toxic effects of these compounds on the activated sludge microfauna. In addition, the CSTR activated sludge microorganisms were more sensitive and did not recover after the toxic shock. Under these conditions, activated sludge presented poor settleability characteristics with a high content of filamentous organisms.4. CONCLUSIONSIn conclusion, the operation of the bench scale activated sludge reactors was studied, under increased concentration of phenol and cyanides. The SBR system showed almost complete phenol degradation for influent concentrations up to 1200 mg/ L-1, while removal of organic matter in terms of COD and BOD5 and of ammonia nitrogen indicated no significant inhibition due to the increased phenol loading. The efficient operation of the SBR unit was maintained during cyanide addition, associated to a high cyanide removal rate exceeding 97%. However, phenol addition affected the operation of the CSTR unit resulting to an effluent of low quality with high organic matter content (BOD5 higher than 150 mg/ L-1, COD higher than 300 mg /L-1).REFERENCES1. Suschka J., Morel J., Mierzwinski S. a