Impact of complexing agents on the processes of sorption treatment of waters containing cobalt

We have investigated the impact on the Co(II) sorption by montmorrilonite of complexing agents: ethylenediaminetetraacetic acid disodium salts (EDTA) and nitrilotriacetic acids (NTA), and fulvic acids (FA). By the impact value of the latter on the Co(II) sorption process by montmorrilonite they can be arranged into a series: EDTA > NTA > FA.     

Biodegradation of novel amino acid derivatives suitable for complexing agents in pulp bleaching applications

The biodegradability of four novel diethanolamine derivative complexing agents was examined by using two biodegradation tests standardised by OECD (301B and 301F). Ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) were employed as reference substances. Biodegradation of the new complexing agents was studied both with unacclimated and acclimated inocula as well as by simulating wastewater treatment in sequencing batch reactors (SBRs). These new complexing agents were of technical grade, and therefore, the results are only indicative but these new compounds hold promise for use as complexing agents in the pulp and paper industry.The novel complexing agents were not readily biodegradable but they showed slight biodegradation. Around 10-30% degradation was found in the SBR where degradation was followed by measurement of concentration. Moreover the novel complexing agents did not have any negative impact on reactor performance as measured by chemical oxygen demand reduction. In the standardised biodegradation tests at best around 50% degradation was observed with the acclimated inoculum and in the prolonged test whereas EDTA and DTPA exhibited no biodegradation. The elevated degradation in acclimated sludge indicates that the water treatment plant microbes are capable of decomposing these molecules under favourable conditions. The total concentration of novel complexing agents decreased slightly during biodegradation tests, while the EDTA and DTPA concentrations remained stable.     

The impact of complexing agents on the processes of sorption treatment of waters containing uranium

The paper investigates the impact of complexing agents: disodium salts of ethylenediaminetetraacetic acid (EDTA) and nitrilotriacetic acid (NTA), acetic acid (NAc), fulvic acids (A), sodium carbonate (Na₂CO₃) on sorption of U(VI) with montmorillonite. We established a complex nature of the relationship between sorption values U(VI) and pH in the presence of complexing agents, which indicates the decisive role of the forms of finding uranium in water treated. By the value of an impact on the process of sorption of U(VI) with montmorillonite the investigation of the complexing agents may be arranged into the following series: EDTA > NTA > Na₂CO₃ > FA.     

Biodegradability of Firefighting Foams

The aim of this study was to evaluate and compare the biodegradation susceptibility of seven different types of foam concentrates (four synthetic and three protein based) used in Europe. The biodegradation of 40 foam concentrates was measured according to OECD 301 F Guideline, based on the CO₂ evolution by the activated sludge during 20 days at 20°C. The foam concentrates were applied at concentrations equivalent to COD = 1000 mg O₂/l. Unexpectedly, the biodegradation rate of the synthetic foam concentrates was higher compared to the protein based ones. Although slight differences exist among the results, a rough order of the foam concentrates biodegradation susceptibility can be established as follows: S > AFFF > Class A > AFFF-AR > FFFP > FP > P.     

Use of complexing agents for effective ion-exchange separation of Co(II)/Ni(II) from aqueous solutions

Cation-exchange separation of Co(2+)/Ni(2+) from aqueous solutions using water-soluble complexing agents of ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), iminodiacetic acid (IDA), and citrate was experimentally studied at 298 K. Experiments were carried out as a function of initial aqueous pH (1.0-6.0), concentration of total metals (1.5-45.0 mol/m(3)), the concentration ratio of two metals (0.1-10) and of complexing agent to the total metals (0-1). It was shown that the exchange selectivity strongly depended on solution pH and was not completely related to the affinity of any metal with the complexing agents. When a certain level of complexing agent was present, highly effective separation could be achieved at an appropriate pH range (for an equimolar metal solution, e.g., pH 2-3 with EDTA and NTA as well as pH>3 with IDA and citrate). The application potential of this method was highlighted for the separation of Co(2+) from binary mixtures in the presence of trace amount of Ni(2+) due to its high selectivity and the smaller amount of the complexing agents needed.     

Observations on the use of iron(II) complexing agents to fractionate the total filterable iron in natural water samples

Analysis of filtered natural water samples using Fe(II) complexing agents (bathophenanthrolinedisulphonic acid, 2,2′-dipyridyl, ferrozine, TPTZ) and acetic acid-sodium acetate buffer (pH 4.6) showed that the absorbance of the iron(II) complex increased with time both in the presence and the absence of a reducing agent (ascorbic acid, hydroxylammonium chloride). Exposure of the samples to 0.1 M HCl (pH 1.3) for 1 h prior to the addition of the complexing reagents resulted in a stable iron concentration which was designated the acid-extractable fraction of the total filterable iron. The results have implications for the complexometric determination of iron fractions other than total iron after acid digestion.     

农药废水生物降解性的影响因素

对６种农药废水生物降解性的影响因素进行了试验研究，表明ｐＨ、温度、污泥浓度、底物浓度、营养及驯化条件均能影响降解农药微生物的活性；适宜的降解条件能促进装置效率的提高和系统的稳定。     

Biodegradability of activated sludge organics under anaerobic conditions

From an experimental and theoretical investigation of the continuity of activated sludge organic (COD) compounds along the link between the fully aerobic or N removal activated sludge and anaerobic digestion unit operations, it was found that the unbiodegradable particulate organics (i) originating from the influent wastewater and (ii) generated by the activated sludge endogenous process, as determined from response of the activated sludge system, are also unbiodegradable under anaerobic digestion conditions. This means that the activated sludge biodegradable organics that can be anaerobically digested can be calculated from the active fraction of the waste activated sludge based on the widely accepted ordinary heterotrophic organism (OHO) endogenous respiration/death regeneration rates and unbiodegradable fraction. This research shows that the mass balances based steady state and dynamic simulation activated sludge, aerobic digestion and anaerobic digestion models provide internally consistent and externally compatible elements that can be coupled to produce plant wide steady state and dynamic simulation WWTP models.     

邻苯二甲酸二(2-乙基己基)酯的微生物降解规律

从北京某污水厂驯化的活性污泥中分离得到邻苯二甲酸二(2-乙基己基)酯(DEHP)的降解菌X,该菌在好氧条件下能以DEHP为唯一的碳源和能源.对其降解10 mg/L DEHP的性能进行了研究,考察了不同pH值、不同菌液初始浓度、不同DEHP初始浓度以及不同降解时间下菌株X对DEHP的降解效果.结果发现:菌株X降解DEHP的最适pH值为6.0左右;DEHP初始浓度和菌液初始浓度存在一个合理的比值,在这一比值下对DEHP的降解率最高;DEHP的降解过程符合指数关系,其半衰期为10 h,36 h后降解率可达到99%.     

羟肟酸类捕收剂的生物降解性能及机理研究

采用振荡培养法研究了混合菌种对羟肟酸类捕收剂的生物降解能力。结果表明:水杨羟肟酸、苯甲羟肟酸、N-羟基邻苯二甲酰亚胺和H205这4种羟肟酸类捕收剂在第7天的生物降解度分别为93.3%、86.9%、86.5%和21.9%,由GB/T15818—2006可知,前3种捕收剂均属于易初级生物降解有机物,H205为难生物降解有机物。羟肟酸类捕收剂的生物降解过程符合一级反应动力学方程,上述4种捕收剂的反应速率常数排序为k水杨羟肟酸k苯甲羟肟酸kN-羟基邻苯二甲酰亚胺kH205。     

Biodegradability and ecotoxicity of commercially available geothermal heat transfer fluids

Commercially available heat transfer fluids used in borehole heat exchangers were investigated for their composition, their biodegradability as well as their ecotoxicity. The main components of the fluids are organic compounds (often glycols) for freezing protection. Biodegradation of the fluids in laboratory studies caused high oxygen depletion as well as nitrate/iron(III) reduction under anaerobic conditions. Additives such as benzotriazoles for corrosion protection were persistent. Ecotoxicity data show that the commercially available fluids caused much higher ecotoxicity than their main organic constituents. Consequently, with regard to groundwater protection pure water as heat transfer medium is recommended. The second best choice is the usage of glycols without any additives. Effects on groundwater quality should be considered during ecological-economical cost-benefit-analyses of further geothermal energy strategies. The protection of groundwater as the most important drinking water resource must take priority over the energy gain from aquifers.     

Biodegradability of meat industry wastes under anaerobic and aerobic conditions

In this study the biodegradation kinetics and the different biologically degradable fractions (readily, slowly and inert fractions) of the organic wastes generated in a meat industry have been estimated under both anaerobic and aerobic conditions. Three of these could be degraded under both conditions, whereas one (pig/cow waste slurries) could only be aerobically degraded since the high ammonia concentration caused inhibition in anaerobic experiments. Mathematical models for anaerobic and aerobic degradations were used to estimate the readily (S(S)) and slowly (X) biodegradable fractions of the meat industry wastes. Using these models, a good agreement was observed between the calculated S(S) fractions for each waste under anaerobic and aerobic conditions, while the calculated X fractions in the aerobic tests were lower than in the anaerobic tests. The experiments, in combination with the modelling, showed that aerobic respirometric test may be used for predicting readily biodegradable fractions under both anaerobic and aerobic conditions provided that ammonia concentration is not significantly high. Thus, for complex organic wastes the length of experiments for estimating biodegradable fractions may be considerably reduced (in this case by 10-12 days).     

Copper complexing properties of melanoidins and marine humic material

Melanoidins, condensation products of sugars and amino acids, represent a key link in the transformation of polysaccharides to humic material in the marine environment. We investigated the complexing capacity of melanoidins that were prepared in deionized water and seawater and separated into different molecular mass fractions. The copper complexing properties of humic material isolated from marine lagoon sediments were determined for comparison. Melanoidins prepared using condensation times longer than two days exibit complexation properties towards copper ions that appear to depend on the basicity of the amino acid precursor and the molecular mass of the product. Pseudomelanoidins, prepared from glucose only, do not complex copper ions at all, regardless of the molecular mass. The highest copper complexing capacity value among melanoidins was measured for a glucose-lysine melanoidin with molecular mass fraction >10 kD (L(T)=2.1x10(-7) molCu(2+)/L). Melanoidin prepared from glucose and glutamic acid >10 kD was similar in complexing capacity to fulvic acid (1-20 kD molecular mass) isolated from lagoon sediments. The presence of calcium and magnesium ions and other macro and microconstituents in the seawater used to prepare melanoidins influences its complexing properties towards metal ions.     

The effect of pH and hardness metal ions on the competitive interaction between trace metal ions and inorganic and organic complexing agents found in natural waters

The effect of pH and hardness metal ions on the interactions between trace metals and both inorganic and organic complexing agents has been studied under conditions simulating natural aquatic conditions, by employing anodic stripping voltammetric titration techniques. The complexation of Bi(III), Cd(II), Cu(II), Pb(II), and Tl(I) with the hydroxo- and carbonato-ligands found in a carbonate medium has been observed to generally increase with increasing pH. Both labile and nonlabile interactions have been observed. Nonlabile interactions are predominant at low pH and labile interactions generally increase with increasing pH. Neither calcium nor magnesium affects these interactions. The complexation of humic acids with trace metals in a carbonate medium was found to be more intense than metal ion-inorganic complexation. Both labile and nonlabile complexation was found; however, no generalizations can be made concerning the type and extent of complexation because of the individual nature of the interactions of each trace metal. Calcium was found to be more effective than magnesium in inhibiting trace metal-organic complexation. The effect of calcium is to inhibit labile complexation and is most pronounced with the cadmium-humic acid system.     

Biodegradability of organic matter associated with sewer sediments during first flush

The high pollution load in wastewater at the beginning of a rain event is commonly known to originate from the erosion of sewer sediments due to the increased flow rate under storm weather conditions. It is essential to characterize the biodegradability of organic matter during a storm event in order to quantify the effect it can have further downstream to the receiving water via discharges from Combined Sewer Overflow (CSO). The approach is to characterize the pollutograph during first flush. The pollutograph shows the variation in COD and TSS during a first flush event. These parameters measure the quantity of organic matter present. However these parameters do not indicate detailed information on the biodegradability of the organic matter. Such detailed knowledge can be obtained by dividing the total COD into fractions with different microbial properties. To do so oxygen uptake rate (OUR) measurements on batches of wastewater have shown itself to be a versatile technique. Together with a conceptual understanding of the microbial transformation taking place, OUR measurements lead to the desired fractionation of the COD. OUR results indicated that the highest biodegradability is associated with the initial part of a storm event. The information on physical and biological processes in the sewer can be used to better manage sediment in sewers which can otherwise result in depletion of dissolved oxygen in receiving waters via discharges from CSOs.     

饮用水生物滤池进出水中有机物可生物降解性研究

介绍一种利用生物滤池进出水中异养细菌生物活性(SOURW)和有机物(CODMn)指标,并通过有机物降解动力学的推导来计算水中可生物降解有机物(BOM)和有机物可生化性的方法.当进、出水中SOURW和CODMn分别为0.13、0.035 6 mgO2/(cm3填料·h)和4.87、4.18 mg/L时,可求得进、出水中可生物降解有机物浓度分别为0.95、0.26 mg/L,有机物可生物降解性分别为0.19、0.062.     

Effect of electrolyte composition, and of added iron(III) in the presence of selected organic complexing agents, on nickel(II) precipitation by lime

The effect of effluent composition involving the common anionic species Cl⁻, SO₄²⁻ and CO₃²⁻ on the efficiency of nickel(II) precipitation, modelling lime (CaO) as the precipitant, has been investigated using the solubility domain approach. Solubility domains were based on the phases that were found to limit metal solubility for systems representing potential effluent composition limits. These phases were found to resemble their mineralized counterparts, but with a lower degree of structural order. At higher SO₄²⁻ and CO₃²⁻ concentrations both gypsum (CaSO₄·2H₂O) and calcite (CaCO₃) were formed, but these had little effect on the observed residual nickel solubility. The calculated solubility domains were found to generally encompass the experimentally determined solubilities, thereby providing quality assurance ranges for hydroxide precipitation. The effect of the complexing anions tartrate and EDTA⁴⁻ on residual Ni(II) in solution as well as the effects of the addition of Fe(III) on the removal of Ni(II) complexed by these species are described.     

Biodegradability and toxicity of sulphonate-based surfactants in aerobic and anaerobic aquatic environments

Four types of commonly used sulphonate-based surfactants (alkane sulphonates, alpha-olefin sulphonates, sulphosuccinates and methyl ester sulphonates) were tested for their aerobic and anaerobic biodegradability as well as for their toxicity to Daphnia magna and Photobacterium phosphoreum to assess the effect of the surfactant structure on those properties. Aerobic biodegradation was evaluated by means of the CO₂ headspace test and anaerobic biodegradation was assessed by a method based on the ECETOC test. All the surfactants tested were readily biodegraded under aerobic conditions. No clear effect of the surfactant structures on the toxicity to the aquatic organisms tested was found. The most significant differences in the surfactants studied were observed in their behaviour under anaerobic conditions. Alkane sulphonates, alpha-olefin sulphonates and methyl ester sulphonates were not mineralized in lab anaerobic digesters despite the fact that the last one showed a certain degree of primary degradation. Nevertheless, these surfactants did not significantly inhibit methanogenic activity at concentrations up to 15 g surfactant/kg dry sludge, a concentration that is much higher than the expected concentrations of these surfactants in real anaerobic digesters. Sulphosuccinates showed a high level of primary biodegradation in anaerobic conditions. However, linear alkyl sulphosuccinates were completely mineralized whereas branched alkyl sulphosuccinates achieved percentages of ultimate biodegradation ≤50%.     

Biodegradability of kraft mill TCF biobleaching effluents: Application of enzymatic laccase-mediator system

The great amount of pollutants released from kraft pulp processes, mainly from cooking and bleaching stages, is one of the most relevant environmental problems in this type of industry. New bleaching sequences are being studied based on the use of oxidative enzymes from fungal cultures. In this study, the bleaching systems consisting of Laccase and different mediators such as 1-hydroxybenzotriazole, violuric acid, syringaldehyde and methyl syringate in the bleaching sequence of Eucalyptus globulus kraft pulp were applied. The main objective of this study is to evaluate the aerobic and anaerobic biodegradability and toxicity to Vibrium fischeri of generated L-stage and total bleaching sequence effluents.The highest levels of aerobic and anaerobic degradation of the generated effluents were achieved for treatments with laccase plus violuric acid, with 80% of aerobic degradation and 68% of anaerobic biodegradation. V. fischeri toxicity was remarkably reduced for all the effluents after aerobic degradation.     

Biodegradability determinations in trickling filter units compared with the OECD Confirmatory Test

The “coupled units test”, i.e. the modification of the OECD Confirmatory Test for the application of non-specific parameters such as the carbon analysis was described in detail in a previous paper, while the present paper discusses the reproducibility of its results, the sensitivity of the method, and the merits and shortcomings of the non-specific analyses (COD and DOC) employed. The extension of the coupled units test principle to trickling filters, a new transinoculation procedure, some square wave feeding experiments and the mathematical separation of the main contributions to the tolerance limits, the analytical and biological variances, are presented.