Optimization of the O3/H2O2 process with response surface methodology for pretreatment of mother liquor of gas field wastewater

• Real ML-GFW with high salinity and high organics was degraded by O₃/H₂O₂ process. • Successful optimization of operation conditions was attained using RSM based on CCD. • Single-factor experiments in advance ensured optimal experimental conditions. • The satisfactory removal efficiency of TOC was achieved in spite of high salinity. • The initial pH plays the most significant role in the degradation of ML-GFW. The present study reports the use of the O₃/H₂O₂ process in the pretreatment of the mother liquor of gas field wastewater (ML-GFW), obtained from the multi-effect distillation treatment of the gas field wastewater. The range of optimal operation conditions was obtained by single-factor experiments. Response surface methodology (RSM) based on the central composite design (CCD) was used for the optimization procedure. A regression model with Total organic carbon (TOC) removal efficiency as the response value was established (R² = 0.9865). The three key factors were arranged according to their significance as: pH>H₂O₂ dosage>ozone flow rate. The model predicted that the best operation conditions could be obtained at a pH of 10.9, an ozone flow rate of 0.8 L/min, and H₂O₂ dosage of 6.2 mL. The dosing ratio of ozone was calculated to be 9.84 mg O₃/mg TOC. The maximum removal efficiency predicted was 75.9%, while the measured value was 72.3%. The relative deviation was found to be in an acceptable range. The ozone utilization and free radical quenching experiments showed that the addition of H₂O₂ promoted the decomposition of ozone to produce hydroxyl radicals (·OH). This also improved the ozone utilization efficiency. Gas chromatography-mass spectrometry (GC-MS) analysis showed that most of the organic matters in ML-GFW were degraded, while some residuals needed further treatment. This study provided the data and the necessary technical supports for further research on the treatment of ML-GFW.     

2010—2019年台州市市区降水化学组成特征及变化趋势

为了解台州市市区大气降水化学成分组成特征及变化规律,对2010—2019年台州市市区降水监测数据进行了统计分析。结果表明:2010—2019年降水样品pH为4.20～4.84夏高冬低,强酸性降水频率下降显著,电导率平均值为3.16 mS/cm。SO_4~(2-)和NO_3~-是降水中最主要的阴离子,NH_4~+和Ca~(2+)是降水中最主要的阳离子。Ca~(2+)浓度在2018年开始有所抬升,SO_4~(2-)和NO_3~-浓度整体呈波动下降趋势。SO_4~(2-)与NO_3~-浓度比均值为1.50,呈下降趋势,同大气中SO_2与NO_2的质量浓度比变化趋势基本一致。SO_4~(2-)和NO_3~-相关性显著,Cl~-、Na~+及Mg~(2+)三者之间具有较好相关性。降水与气态污染物相关性不大,对颗粒物有明显冲刷去除作用。SO_2和NO_x的排放量显著下降,酸雨污染呈现改善过程。     

Inhibition character of crotonaldehyde manufacture wastewater on biological acidification

• The inhibition of the main organic pollutions in CMW was demonstrated. • Variations of AK and BK showed a high correlation with the SAA of Ac and n-Bu. • The inhibitory degree was in the order of Ac>n-Bu for individual toxicants. • Biodegradation products of the main toxicants were analyzed. This work aims to investigate the inhibitory effect of crotonaldehyde manufacture wastewater (CMW) on biological acidification. To reveal the inhibitory effect of wastewater to the anaerobic granular sludge (AnGS), variations of the specific acidogenic activity (SAA) and activities of key enzymes were investigated. The results indicated that the dosage of CMW causing a 50% effect concentration (EC₅₀) on the activity of total volatile fatty acids (TVFA) production was 380 mg COD/g VSS. The inhibitory effect of individual toxicants in CMW on the activity of TVFA production were in the order of crotonaldehyde>ethyl sorbate>(E,E)-2,4-hexadienal, and their inhibitory degrees on individual VFA products were acetic acid (Ac)>n-butyric acid (n-Bu), which could correspond to the variations in the activities of acetate kinase (AK) and butyrate kinase (BK). Furthermore, the combined effect of three toxicants on the activity of TVFA production was significantly higher than that of any individual toxicant, and the contribution of the relative toxicity to CMW was 77.27%. Additionally, the biodegradation products of the main toxicants indicated that the removal of crotonaldehyde and (E,E)-2,4-hexadienal was primarily due to the hydrogenation of alkene and aldehyde and the oxidation of aldehyde. Nevertheless, the removal of ethyl sorbate was primarily based on adsorption. In conclusion, biological acidification has a limited ability to treatment CMW, therefore, a further pretreatment technology should be used to remove the main toxicant of wastewater.     

高氯酸铁可见分光光度法测定水中叠氮化物研究

基于Fe~(3+)显色技术,建立了测定地表水、地下水、生活污水和工业废水中叠氮化物的高氯酸铁分光光度法。研究结果表明:N_3~-与Fe~(3+)反应生成的棕红色络合物的特征吸收峰为454 nm;氨基磺酸铵可有效掩蔽NO_2~-的干扰,蒸馏能消除色度、CN~-、SCN~-硫化物等对测定的影响;当取样体积为150 mL、蒸馏定容体积为100 mL、使用10 mm比色皿时,方法检出限为0.08 mg/L(以N_3~-计),测定下限为0.32 mg/L;平均回收率为88.0%~104%,相对标准偏差(n=6)为0.3%～5.6%。对实际工业废水样品进行了测定,结果为1.37 mg/L。该方法准确度高、精密度好、操作简单,能够满足水污染物排放标准中叠氮化物的测定要求。     

Ingestion and egestion of microplastic by aquatic insects in Egypt wastewater

Microplastics (MPs) are frequently regarded as environmental and biota contaminants. Yet, research on the accumulation of MPs in living entities, particularly aquatic insects that serve as food resources in the aquatic food chain, is limited. This study to investigate the accumulation of MPs in aquatic insects from water and sediment in an Egyptian wastewater basin. Four typical freshwater insect groups were used. The highest MP load per gram wet weight was reported by collector-gatherers (Chironomus sp. and Hydrophilus sp.), followed by collector-filterers (Culex sp.) with the second highest MP load. However, Predators (Aeshna sp.) had the lowest values. Also, the present results showed a reduction in the number of MPs in all insect taxa tested after a 24 h depuration time, with differences in the observed egestion ability. The mean number of MPs per individual significantly reduced after 24 h in both Chironomus sp. and Culex sp. larvae, where 53% and 40% of MPs particles were ejected from them, respectively. However, the ability of MP egestion decreases in Aeshna sp. nymph (25%), and the lowest proportion of ejection was observed in Hydrophilus sp. adults (9%). Polyethylene terephthalate fibers were the most abundant type of MP in both sediment and water, followed by fragments (polyethylene and polypropylene). Yet, only polyester fibers were detected in the various insect species. The average length of fibers in the various insects was somewhat shorter than in the surrounding environment. The current study reveals that MP ingestion by aquatic insects is not always related to levels of pollution in the environment, since other factors such as feeding strategies may play a role in MP ingestion. Based on these observations, further studies should be carried out on studies on toxicological impacts of MPs on freshwater/aquatic biota.     

贵州喀斯特山区不同种植年限花椒根际土壤细菌群落结构特征研究

以贵州花江峡谷花椒(Zanthoxylum bungeamun)林为研究对象,采用16S rRNA高通量测序技术,分析种植5、10、20、30 a花椒根际土壤细菌群落结构和多样性特征,探讨不同种植年限花椒土壤理化因子对根际细菌群落分布的影响,为喀斯特石漠化地区花椒农业可持续发展提供有效的理论依据。结果表明,随着花椒种植年限的增加,土壤含水率、pH和有效磷逐渐升高,有机质、铵态氮和硝态氮含量先降低后升高(P<0.05)。根际土壤细菌Shannon、Simpson指数总体呈现上升趋势,OTUs、Chao1指数在10a较低。PCo A分析显示,不同种植年限花椒根际细菌群落组成差异显著,并且随着年限的增加,群落结构趋于相似;差异指示种分析表明,5—30a差异指示种分别为Firmicutes(厚壁菌门)、Cyanobacteria(蓝藻菌门)、Planctomycetes(浮霉菌门)、Entotheonellaeota(肠杆菌门)。RDA分析表明,有机质和含水率与细菌群落分布显著相关(P<0.05)。系统发育多样性分析表明,丰富类群多样性与环境因子存在较多的正相关,稀有类群比丰富类群有更强的发育信号。Bug Base预测分析发现:随着年限增加根际土壤好氧细菌增加,厌氧细菌下降,5、10 a氧化胁迫耐受菌低于20、30 a,致病菌在5、10 a高于20、30 a。综上,种植年限影响了花椒根际土壤细菌群落多样性,不同年限根际土壤肥力不同使得土壤细菌选择性生长,随着一定时间发育花椒抗病能力提高。     

旋流气浮除油装置预处理含油污水

在河南油田开展旋流气浮除油装置的现场试验,考察进水流量和曝气量对旋流气浮除油装置除油效果的影响。试验结果表明:在进水流量为1.8 m³/h、曝气量为0.5 L/min时,除油率最高达到96.03%;在不添加任何药剂的条件下,装置处理效果稳定;连续运行6 d内,进水含油量为174.57~1 193.15 mg/L时,出水含油量可以保持在137.38 mg/L以下,除油率为58.58%~94.53%。     

工业废水毒性评估与致毒物质鉴别技术进展

综述了工业废水毒性的化学评估方法、生物毒性评估方法、毒性鉴定评估(TIE)程序以及效应引导的毒物鉴别分析(EDA)中污染物提取、分离、毒性测试、致毒物质识别等技术。指出,工业废水毒害风险评估方法正逐渐向化学分析与生物毒性测试相结合的关键致毒物质鉴别方法转变,便捷、高通量是致毒物质鉴别技术的发展方向,质谱技术及替代定性监测技术的发展将提供更为准确、便捷的致毒物质鉴别方法,为工业废水潜在风险防控提供依据。     

钻孔间距对水力压裂促抽煤层瓦斯的影响

针对定量确定合理钻孔间距困难问题，基于损伤力学和多场耦合理论，建立了水力压裂和瓦斯抽采的煤层流固耦合模型，包括和水运移场、应力场以及孔隙度、渗透率演化方程，并采用Comsol联合Matlab求解，研究了不同钻孔间距时压裂和抽采过程中煤层弹模、损伤值、渗透率、瓦斯压力、抽采量和压裂贯通时间的变化规律。结果表明:耦合模型可较准确地模拟煤层水力压裂和瓦斯抽采过程；压裂贯通时间与钻孔间距呈指数增长关系；在马堡煤矿，当钻孔间距为4~8 m时，压裂损伤区在抽采孔贯通，渗透率呈“n”型曲线，瓦斯抽采后，瓦斯压力迅速下降，抽采有效区随间距的增加而增大；当钻孔间距为9~12 m时，压裂损伤区未贯通，煤层渗透率呈“m”型曲线，抽采有效区随间距的增加而减小，与间距4~8 m相比，瓦斯抽采量较小。     

高含盐废水脱盐处理技术研究进展

综述了几种常见的高含盐废水脱盐处理技术的发展历程、工艺原理、优缺点及目前的研究进展，分析了热分离、膜分离、电渗析、离子交换、电吸附、微生物脱盐等方法的优缺点，展望了未来废水脱盐工艺的发展方向。指出：脱盐方法将根据各类水体的水质特点更加精细化；多种脱盐技术联合应用也是今后废水脱盐的发展方向。