Biodegradation of nonylphenol polyethoxylates under Fe(III)-reducing conditions

Biodegradation behavior of nonylphenol polyethoxylates (NPEOs) under Fe(III)-reducing conditions was investigated. The study demonstrated that NPEOs could be rapidly biodegraded under Fe(III)-reducing conditions. Almost 60% of the total NPEOs were removed within three days and the maximum biodegradation rate was 34.95+/-0.84 microM d(-1). NPEOs were degraded via sequential removal of ether units under Fe(III)-reducing conditions. No nonylphenol polyethoxy-carboxylates (NPECs) were formed in this process. This ether removal process was coupled to Fe(III) reduction. Nonylphenol (NP), nonylphenol monoethoxylate (NP1EO), and nonylphenol diethoxylate (NP2EO) slightly accumulated in the anaerobic biodegradation process. The accumulation of these estrogenic metabolites led to a significant increase in the estrogenic activity during the biodegradation period. The calculated estrogenic activity reached its top on day 14 when the total concentration of these estrogenic metabolites was maximal. This is the first report of the primary biodegradation behavior of NPEOs under Fe(III)-reducing conditions. These findings are of major environmental importance in terms of the environmental behavior of NPEO contaminants in natural environment.     

壬基酚聚氧乙烯醚在印染废水处理工艺中的去除研究

为减少印染助剂壬基酚聚氧乙烯醚(nonylphenol ethoxylates,NPEO)及其降解产物壬基酚(nonylphenol,NP)随印染废水进入水体造成的不利环境影响,对2种常规印染废水处理净水工艺处理含NPEO的模拟印染废水效率开展了研究。研究发现,结合厌氧水解和曝气氧化的生物处理工艺能迅速地将废水中NPEO去除,去除率达到90%以上,但排水中残余一定含量的NP、短链NPEO和短链壬基酚聚氧乙烯醚酸酯(nonylphenol polyethoxycarboxylate,NPEC),在减少排水中NP、短链NPEO和短链NPEC浓度方面,接触氧化法比活性污泥法效果更好。排水中的NP和短链NPEO来自厌氧水解阶段长链NPEO的降解;减少排水中NP、短链NPEO需要减少厌氧水解阶段产生的短链NPEO。     

Degradation and plant uptake of nonylphenol (NP) and nonylphenol-12-ethoxylate (NP12EO) in four contrasting agricultural soils

Nonylphenol polyethoxylates (NPEOs) are surfactants found ubiquitously in the environment due to widespread industrial and domestic use. Biodegradation of NPEOs produces nonylphenol (NP), an endocrine disruptor. Sewage sludge application introduces NPEOs and NP into soils, potentially leading to accumulation in soils and crops. We examined degradation of NP and nonylphenol-12-ethoxylate (NP12EO) in four soils. NP12EO degraded rapidly (initial half time 0.3-5 days). Concentrations became undetectable within 70-90 days, with a small increase in NP concentrations after 30 days. NP initially degraded quickly (mean half time 11.5 days), but in three soils a recalcitrant fraction of 26-35% remained: the non-degrading fraction may consist of branched isomers, resistant to biodegradation. Uptake of NP by bean plants was also examined. Mean bioconcentration factors for shoots and seeds were 0.71 and 0.58, respectively. Removal of NP from the soil by plant uptake was negligible (0.01-0.02% of initial NP). Root concentrations were substantially higher than shoot and seed concentrations.     

Treatment of distillery spent-wash by ozonation and biodegradation: significance of pH reduction and inorganic carbon removal before ozonation.

This study is aimed at exploring strategies for mineralization of refractory compounds in distillery effluent by anaerobic biodegradation/ozonation/aerobic biodegradation. Treatment of distillery spent-wash used in this research by anaerobic-aerobic biodegradation resulted in overall COD removal of 70.8%. Ozonation of the anaerobically treated distillery spent-wash was carried out as-is (phase I experiments) and after pH reduction and removal of inorganic carbon (phase II experiments). Introduction of the ozonation step resulted in an increase in overall chemical oxygen demand (COD) removal, with the highest COD removals of greater than 95% obtained when an ozone dose of approximately 5.3 mg ozone absorbed/mg initial total organic carbon was used. The COD removal during phase II experiments was slightly superior compared with phase I experiments at similar ozone doses. Moreover, efficiency of ozone absorption from the gas phase into distillery spent-wash aliquots was considerably enhanced during phase II experiments.     

Fenton氧化法深度处理甲醛废水

采用Fenton氧化法深度处理经生化降解后的甲醛废水,结果表明,Fenton氧化法深度处理甲醛废水是可行的,在合适的反应条件下,降解初始COD为150 mg/L左右的甲醛废水,COD去除率达30%以上;Fe2+与H2O2的投加比例、投加量及投加方式、反应温度、pH、反应时间对处理效果都有不同程度的影响。     

Enhancement of chemical-oxygen demand and color removal of distillery spent-wash by ozonation.

Distillery spent-wash has very high organic content (75,000 to 125,000 mg/L chemical-oxygen demand [COD]), color, and contains difficult-to-biodegrade organic compounds. For example, anaerobic treatment of the distillery spent-wash used in this study resulted in 60% COD reduction and low color removal. Subsequent aerobic treatment of the anaerobic effluent resulted in enhancement of COD removal to 66%. In this paper, the effect of ozonation on various properties of the anaerobically treated distillery effluent, including the effect on its subsequent aerobic biodegradation, was investigated. Ozonation of the anaerobically treated distillery effluent at various ozone doses resulted in the reduction of total-organic carbon (TOC), COD, COD/TOC ratio, absorbance, color, and increase in the biochemical-oxygen demand (BOD)/COD ratio of the effluent. Further, ozonation of the anaerobically treated distillery effluent at an ozone dose of 2.08 mg/mg initial TOC and subsequent aerobic biodegradation resulted in 87.4% COD removal, as compared to 66% removal when ozonation was not used.     

Organic micropollutants’ distribution within sludge organic matter fractions explains their dynamic during sewage sludge anaerobic digestion followed by composting

The simultaneous fate of organic matter and 4 endocrine disruptors (3 polycyclic aromatic hydrocarbons (PAHs) (fluoranthene, benzo(b)fluoranthene, and benzo(a)pyrene) and nonylphenols (NP)) was studied during the anaerobic digestion followed by composting of sludge at lab-scale. Sludge organic matter was characterized, thanks to chemical fractionation and 3D fluorescence deciphering its accessibility and biodegradability. Total chemical oxygen demand (COD) removal was 41% and 56% during anaerobic digestion and composting, respectively. 3D fluorescence highlighted the quality changes of organic matter. During continuous anaerobic digestion, organic micropollutants’ removal was 22?±?14%, 6?±?5%, 18?±?9%, and 0% for fluoranthene, benzo(b)fluoranthene, benzo(a)pyrene, and nonylphenols, respectively. Discontinuous composting allowed to go further on the organic micropollutants’ removal as 34?±?8%, 31?±?20%, 38?±?10%, and 52?±?6% of fluoranthene, benzo(b)fluoranthene, benzo(a)pyrene, and nonylphenols were dissipated, respectively. Moreover, the accessibility of PAH and NP expressed by their presence in the various sludge organic matter fractions and its evolution during both treatments was linked to both the quality evolution of the organic matter and the physicochemical properties of the PAH and NP; the presence in most accessible fractions explained the amount of PAH and NP dissipated.

     

Mutagenicity of anaerobic fenitrothion metabolites after aerobic biodegradation

Previous studies have revealed that the mutagenicity of fenitrothion increases during anaerobic biodegradation, suggesting that this insecticide's mutagenicity could effectively increase after it pollutes anaerobic environments such as lake sediments. To investigate possible changes to the mutagenicity of fenitrothion under aerobic conditions after it had already been increased by anaerobic biodegradation, batch incubation cultures were maintained under aerobic conditions. The mutagenicity, which had increased during anaerobic biodegradation, decreased under aerobic conditions with aerobic or facultative bacteria, but did not disappear completely in 22 days. In contrast, it did not change under aerobic conditions without bacteria or under continued anaerobic conditions. These observations suggest that the mutagenicity of anaerobically metabolized fenitrothion would not necessarily decrease after it arrives in an aerobic environment: this would depend on the presence of suitable bacteria. Therefore, fenitrothion-derived mutagenic compounds may pollute the water environment, including our drinking water sources, after accidental pollution of aerobic waters. Although amino-fenitrothion generated during anaerobic biodegradation of fenitrothion was the principal mutagen, non-trivial contributions of other, unidentified metabolites to the mutagenicity were also observed.     

水葫芦压榨液厌氧发酵及其发酵液对青菜种子发芽和生长的影响

研究了水葫芦压榨液厌氧发酵过程物质的变化,分析了水葫芦压榨液的发酵液(简称发酵液)对青菜种子发芽及后续生长的影响.结果表明,厌氧发酵能显著降低压榨液中的COD,在厌氧发酵结束时,COD从5 377.0mg/L下降到730.0mg/L,下降86.4%;TN从126.6 mg/L下降到79.7 mg/L,氮素流失37.0%,且主要发生在厌氧发酵初期;TP从31.1 mg/L下降到25.0 mg/L,下降19.6%;发酵液中悬浮物(SS)和可溶性固体(DS)分别下降到719、600 mg/L.分别用蒸馏水、水葫芦压榨液和各阶段的发酵液(发酵时间分别为6、20、27、30 d)进行青菜种子发芽试验(历时10 d),平均发芽率分别达到79%、54%、51%、82%、87%、89%.在10 d的青菜苗生长时间内,平均苗高与发酵时间呈显著正相关,说明发酵液具有作为植物液体肥料使用的潜力.     

Rhodobacter sp. NP25b菌株缺氧降解壬基酚聚氧乙烯醚的研究

从城市污水处理厂活性污泥中分离得到一株能够在缺氧条件下以壬基酚聚氧乙烯醚(NPEOs)为惟一碳源和能源生长的菌株NP25b.经生理生化鉴定和16S rRNA基因序列分析,该菌株属于红细菌属(Rhodobacter sp.),对该菌株降解NPEOs的特性进行了研究.结果表明,在缺氧条件下,菌株NP25b在7 d内对初始底物浓度为400 mg/L NPEOs的降解率可达84%.利用液相色谱-质谱(LC-MS)和气相色谱-质谱(GC-MS)对NPEOs降解中间产物进行了分析,结果表明,主要降解产物为短链NPEOs和壬基酚聚氧乙烯醚乙酸(NPECs),其中包括具有较强内分泌干扰效应的NP1EO.该菌株能够代谢含有疏水基团的聚氧乙烯醚类表面活性剂,例如辛基酚聚氧乙烯醚和脂肪醇聚氧乙烯醚.推测菌株NP25b降解NPEOs是通过乙氧基(EO)链末端氧化后逐步切割完成的.     

苯酚的厌氧生物处理

采用不断增加苯酚浓度而降低葡萄糖浓度的方法可驯化厌氧污泥中的微生物,使厌氧污泥最终以苯酚为唯一碳源生长,可显著提高厌氧污泥降解苯酚的能力;对苯酚间歇厌氧降解过程进行了分析。苯酚浓度在0～1.680 mg/L范围内,其厌氧降解过程符合一级动力学。Aiba模型、Haldane模型和Teisser 模型均可很好地描述处于对数期时厌氧污泥的比生长速率与初始底物浓度之间的关系,其中以Teisser 模型模拟的效果最好。将驯化污泥接种于UASB中可实现对含酚废水处理的连续运行,最大的有机负荷达2 g COD/（L·d）,稳定运行时苯酚的去除率可维持在96%以上。     

厌氧流化床微生物燃料电池同步除碳脱氮产电性能影响因素

研究了厌氧流化床微生物燃料电池(AFB-MFC)除碳脱氮产电性能的影响因素。结果表明:(1)AFB-MFC对NH4+-N的去除不起作用。电压下降主要是由于进水有机基质浓度下降造成。(2)不添加NO3--N时,在满足AFB-MFC脱氮所需的电子供体条件下增加进水COD/TN有利于AFB-MFC产电。(3)3种无机氮共存下,AFB-MFC在进水有机碳与无机氮质量比(C/N)不低于1.37时,对COD、NO2--N和NO3--N具有理想的去除效果。AFB-MFB在一定进水C/N范围内(1.37～2.50),能得到稳定的输出电压及功率密度。(4)固定进水C/N时,AFB-MFC在高碳氮负荷下仍能得到较理想的NO2--N、NO3--N、COD去除效果,AFB-MFC对NH4+-N去除效果不明显;增加碳氮负荷,AFB-MFC输出电压及功率密度没有明显的改变。(5)有机基质浓度不变下,AFB-MFC中充足的电子供体可保证较高的NO3--N、COD去除率。AFB-MFC输出电压及功率密度随着时间延长而先增加至稳定值后下降。     

Anaerobic nonylphenol ethoxylate degradation coupled to nitrate reduction in a modified biodegradability batch test

The aim of this work was to elucidate the role of nitrate as a terminal electron acceptor on the biodegradation of NPEO. We have characterized the products of NPEO degradation by mixed microbial communities in anaerobic batch tests by means of HPLC, ¹H NMR and GC–MS. Anaerobic degradation of NPEO was strictly dependent on the presence of nitrate. Within seven days of anoxic incubation, NP2EO appeared as the major degradation product. After 21 days, NP was the main species detected, and was not degraded further even after 35 days. Nitrate concentration decreased in parallel with NPEO de-ethoxylation. A transient accumulation of nitrite was observed within the time period in which NP formation reached its maximum production. The observed generation of nonylphenol coupled to nitrate reduction suggests that the microbial consortium possessed an alternate pathway for the degradation of NPEO, which was not accessible under aerobic conditions.     

Comparison of biodegradation of surfactants in soils and sludge-soil mixtures by use of 14C-labelled compounds and automated respirometry

The biodegradability of dodecyl benzene sulphonate (LAS), nonylphenol-di-ethoxylate (NP2EO) and tridecyl-tetra-ethoxylate (LAE) in soil was examined by use of 14C experiments at two concentrations (10 and 400 mg/kg). Increasing the concentration of test chemical from 10 to 400 mg/kg resulted in a decrease in the relative maximum mineralization rate and an increase in the estimated lag times of a factor of approximately 3.5. In sludge-amended soil, the highest expected environmental concentration (just after sludge application) will be around 10 mg/kg for linear alkylbenzene sulphonate (LAS), while the concentration of NP2EO and linear alcohol ethoxylates (LAE) will be much lower. However, when using a respirometric method it is necessary to use a higher concentration of test substance in order to detect biodegradation. In our experiment, amendment with anaerobically digested sludge resulted in a decrease in the mineralization of LAS, NP2EO and LAE for all soils. Respirometric experiments were carried out at 400 mg/kg and could be used for estimation of biodegradation potential of LAS, NP2EO and LAE in soil and sludge-amended soil. For LAS, the results obtained from the respirometric experiments were similar to the results obtained in the 14C experiments, whereas NP2EO and LAE showed a faster degradation in the respirometric experiments.     

Impact of sewage sludge treatment processes on the removal of the endocrine disrupters nonylphenol ethoxylates

Several treatment processes of mixed sludge naturally contaminated with nonylphenol ethoxylates (NPE) were compared in order to evaluate their efficiency for the removal of these endocrine disrupters. Anaerobic and aerobic treatments were carried out in continuous stirred tank reactors, operated separately or combined together, at mesophilic and thermophilic temperatures and with or without ozone post-treatment. Anaerobic mesophilic removal of NPE consisted of complete removal of nonylphenol diethoxylate, incomplete removal of nonylphenol monoethoxylate and non stoechiometric production of nonylphenol, with consequently a NPE removal of 25%. At thermophilic temperature, anaerobic digestion led to an increase of the total solids removal efficiency, while improving NPE degradation (30%). Under thermophilic aerobic condition, the three compounds were removed simultaneously with a NPE removal efficiency higher than under anaerobic condition (39%). This removal is always well correlated to the total solids removal meaning that bioavailability remains the main limiting factor. Combination of either thermophilic aerobic-mesophilic anaerobic or mesophilic anaerobic-ozonation treatments enhanced the NPE removal by comparison to single systems (45% and 48%, respectively). These results confirm the high potential of existing and up-grading sewage sludge treatments to degrade such refractory and aged compounds.     

Biodegradation of benzene, toluene, ethylbenzene and xylenes in gas-condensate-contaminated ground-water

The rate and extent of biodegradation of benzene, toluene, ethylbenzene and xylenes (BTEX) in ground-water was studied in samples from a contaminated site which contained total BTEX concentrations of up to 20 000 microg litre(-1). All compounds were rapidly degraded under natural aerobic conditions. Elevation of incubation temperature, supply of organic nutrients or addition of inorganic fertiliser did not increase the rate or extent of biodegradation and it appeared that oxygen supply was the factor limiting BTEX degradation at this site. Attempts to increase the dissolved oxygen concentration in the ground-water by the addition of hydrogen peroxide to give a final concentration of 200 mg litre(-1) resulted in the complete inhibition of biodegradation. No biodegradation occurred under anaerobic conditions except when nitrate was provided as a terminal electron acceptor for microbial respiration. Under denitrifying conditions there was apparent biodegradation of benzene, toluene, ethyl-benzene, m-xylene and p-xylene but o-xylene was not degraded. Degradation under denitrifying conditions occurred at a much slower rate than under oxygenated conditions.     

Treatment of coking wastewater by an advanced Fenton oxidation process using iron powder and hydrogen peroxide

In this study the treatment of coking wastewater was investigated by an advanced Fenton oxidation process using iron powder and hydrogen peroxide. Particular attention was paid to the effect of initial pH, dosage of H₂O₂ and to improvement in biodegradation. The results showed that higher COD and total phenol removal rates were achieved with a decrease in initial pH and an increase in H₂O₂ dosage. At an initial pH of less than 6.5 and H₂O₂ concentration of 0.3 M, COD removal reached 44-50% and approximately 95% of total phenol removal was achieved at a reaction time of 1 h. The oxygen uptake rate of the effluent measured at a reaction time of 1 h increased by approximately 65% compared to that of the raw coking wastewater. This indicated that biodegradation of the coking wastewater was significantly improved. Several organic compounds, including bifuran, quinoline, resorcinol and benzofuranol were removed completely as determined by GC-MS analysis. The advanced Fenton oxidation process is an effective pretreatment method for the removal of organic pollutants from coking wastewater. This process increases biodegradation, and may be combined with a classical biological process to achieve effluent of high quality.     

Determination and distribution characteristics of degradation products of nonylphenol polyethoxylates in the rivers of Taiwan

Concentrations of degradation products of nonylphenol polyethoxylates (NPEOs) were analyzed in river water samples in order to determine the distribution characteristic of these alkylphenolic compounds in 18 major rivers of Taiwan. The degradation products of NPEOs were detected in all river samples, with the dicarboxylates alkylphenolic degradation products (CAPEC) being detected most frequently and at the highest concentrations. Concentrations of NP and NP1EO in rivers ranged from n.d. to 5.1 μg l⁻¹ and n.d. to 0.5 μg l⁻¹, respectively. The total concentrations of shortened carboxylates (i.e., NP1EC + NP2EC + NP3EC) and dicarboxylates alkylphenolic degradation products (CAP1EC + CAP2EC) ranged from n.d. to 63.6 μg l⁻¹ and n.d. to 94.6 μg l⁻¹, respectively. Concentrations of NP2EC, NP3EC and all CAPEC residues were determined semi-quantitatively by comparing with the internal standard. Significantly higher concentrations of CAPEC residues were detected in the river waters as compared to those of NP, NP1EO and NPEC degradation products and the average proportions of these compounds in the samples of the rivers were as follows: NP + NP1EO was 5 ± 2.5%, total NPEC was 25 ± 12%, and total CAPEC was 70 ± 12%. The high concentration ratios of CAPEC/NPEC illustrate that aerobic biodegradation plays a main route in the fate of NPEO in the rivers of Taiwan.     

剩余污泥发酵产酸特征及基质释放规律研究

剩余污泥发酵既能实现污泥减量,又能获得污水生物脱氮除磷所需的挥发性脂肪酸VFAs等。采用序批式污泥发酵实验,在(30±1)℃的条件下,研究剩余污泥投配比对序批式污泥发酵系统污泥减量、产酸以及基质释放过程的影响,探索VFAs生成最大化的条件。实验结果表明:投加接种污泥不能明显提高序批式污泥发酵系统剩余污泥的减量效果,但可以改善污泥的产酸特性;当污泥投配比大于50%时,发酵过程中将出现2个VFAs浓度峰,且第二次峰浓度更大;较为理想的序批式污泥发酵投配比是60%~80%、发酵时间为5 d或25 d,前者VFAs表观转化率最大(约24%),后者发酵液中VFAs浓度最高(约600 mg/L);发酵过程中,NH4+-N总体呈上升趋势,磷浓度发酵5 d时达到最大值。     

影响有机污染物在土壤中的迁移、转化行为的因素

本文介绍了有机污染物在土壤中的吸附与解吸附、渗滤、挥发和降解等行为过程。探讨了吸附与解吸附机理、土壤有机质含量和类型、水分含量及温度等对此过程的影响。依据某些典型的化合物行为模型,论述了影响土壤中有机污染物渗滤的因素。有机污染物需要先从土壤深层迁移至地表,然后挥发至大气,在土壤中迁移的速率较慢,控制着整个挥发过程,可用Ｆｉｃｋ 第二定律来描述。有机污染物在土壤中的非生物降解主要包括氧化－ 还原、光解和水解等反应。土壤中的Ｏ２ 含量、土壤有机质成分和含量、辐射强度、光谱分布、土壤水分含量、温度和ｐＨ 值等都会影响非生物降解过程。其中有些因素通过影响微生物的生物活性,还影响有机污染物的生物降解