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.     

Characteristics analysis of near-field and far-field aerodynamic noise around high-speed railway bridge

Environmental Science and Pollution Research - The aerodynamic noise around the high-speed railway bridge is studied by the train-bridge-flow field numerical model and theory analysis. With the...     

Sewage sludge ditch for recovering heavy metals can improve crop yield and soil environmental quality

• Indirect use of sludge in ditches alongside plants was tested in field experiments. • The dried and stabilized sludge in ditches was recovered with heavy metals. • Cd, Pb, Cu and Zn in the planted soil were all in a safe range. • The indirect use of sludge increased plant yield, soil N content and C storage. The treatment and disposal of municipal sewage sludge (MSS) is an urgent problem to be resolved in many countries. Safely using the nutrients within MSS to increase crop yield and enhance the fertility of poor soil could contribute to achieving sustainable development. An indirect use of MSS in ditches alongside Pennisetum hybridum plants was studied in field plots for 30 months and the contents of heavy metals and macronutrients were monitored in soil, sludge and plant samples. We found that the yield of P. hybridum was significantly increased by 2.39 to 2.80 times and the treated plants had higher N content compared with no sludge. In addition, the organic matter (OM) and N contents in the planted soil increased significantly compared with the initial soil. The OM content in the planted soil of the MSS treatment was 2.9 to 5.2 times higher than that with no sludge, and N increased by 2.0 to 3.8 times. However, MSS had no significant effect on the N, P and K contents in the soil at the bottom of the MSS ditch, and the content of heavy metals (Cd, Pb, Cu and Zn) were also within the safe range. Moreover, the moisture content and phytotoxicity of MSS after this indirect use were reduced and the heavy metal contents changed little, which is favorable to the further disposal of recovered MSS. Therefore, this indirect use of MSS is beneficial to agricultural production, soil quality and environmental sustainability.     

Effects of climate variables on the transmission of COVID-19: a systematic review of 62 ecological studies

Environmental Science and Pollution Research - The new severe acute respiratory syndrome coronavirus 2 was initially discovered at the end of 2019 in Wuhan City in China and has caused one of the...     

Environmental effects and risk control of antibiotic resistance genes in the organic solid waste aerobic composting system: A review

• ARGs were detected in livestock manure, sludge, food waste and fermentation dregs. • The succession of microbial community is an important factor affecting ARGs. • Horizontal transfer mechanism of ARGs during composting should be further studied. Antibiotic resistance genes (ARGs) have been diffusely detected in several kinds of organic solid waste, such as livestock manure, sludge, antibiotic fermentation residues, and food waste, thus attracting great attention. Aerobic composting, which is an effective, harmless treatment method for organic solid waste to promote recycling, has been identified to also aid in ARG reduction. However, the effect of composting in removing ARGs from organic solid waste has recently become controversial. Thus, this article summarizes and reviews the research on ARGs in relation to composting in the past 5 years. ARGs in organic solid waste could spread in different environmental media, including soil and the atmosphere, which could widen environmental risks. However, the conventional composting technology had limited effect on ARGs removal from organic solid waste. Improved composting processes, such as hyperthermophilic temperature composting, could effectively remove ARGs, and the HGT of ARGs and the microbial communities are identified as vital influencing factors. Currently, during the composting process, ARGs were mainly affected by three response pathways, (I) “Microenvironment-ARGs”; (II) “Microenvironment-microorganisms-ARGs”; (III) “Microorganisms-horizontal gene transfer-ARGs”, respectively. Response pathway II had been studied the most which was believed that microbial community was an important factor affecting ARGs. In response pathway III, mainly believed that MGEs played an important role and paid less attention to eARGs. Further research on the role and impact of eARGs in ARGs may be considered in the future. It aims to provide support for further research on environmental risk control of ARGs in organic solid waste.     

太湖流域河流入河污染负荷通量与入湖水质响应关系分析——以殷村港为例

以2020年1—12月太湖主要入湖河流殷村港水质自动监测站的监测数据及2020年太湖水位资料为依据,构建了一维水量水质耦合数学模型,建立了入河污染负荷通量与入湖控制断面水质响应关系,以入太湖控制断面殷村港站达Ⅲ类水质水为目标,模拟计算了殷村港站主要污染物入湖水质变化过程。结果表明,殷村港站高锰酸盐指数、氨氮、总磷等水质指标浓度最大值均明显的降低,其中氨氮浓度降低幅度相对较大,主要集中于3—6月;高锰酸盐指数和总磷日均入河污染负荷通量变化相对较小,氨氮日均入河污染负荷通量降低幅度相对较大;殷村港站高锰酸盐指数、氨氮、总磷等水质指标年入河污染负荷削减量分别为24.17,41.43,3.87 t。提出,基于核算出的削减量需进一步结合污染负荷通量过程和污染源溯源分析,确定不同水质指标下入河污染负荷控制方向,为科学合理规划殷村港主要污染物的入河污染负荷总量控制提供科学依据。     

贵阳市城区PM10和PM2.5水溶性离子特征分析

分别于2013年10月和2014年2月、5月、7月在贵阳市城区3个环境空气质量监测国控点位（南明区市监测站、云岩区黔灵公园马鞍山和观山湖区贵阳一中）进行PM₁₀、PM_2.5样品采集，并对10种水溶性离子（SO₄^2-、NO₂^-、NO₃^-、NH₄⁺、Cl^-、F^-、Na⁺、K⁺、Mg²⁺、Ca²⁺）的含量进行了分析。结果表明，研究时段内，贵阳市3个点位PM₁₀、PM_2.5平均质量浓度分别为（64.8±25.5）、（46.6±21.2）μg/m³。其中，云岩区黔灵公园马鞍山点位的颗粒物浓度最低，南明区市监测站点位最高。3个点位PM_2.5平均浓度与PM₁₀平均浓度的比值为0.719，表明贵阳市城区PM₁₀中，PM_2.5占主导地位。水溶性离子分析显示，SO₄^2-、NO₂^-、NO₃^-、NH₄⁺、Cl^-、F^-、Na⁺、K⁺主要分布在PM_2.5中，Mg²⁺、Ca²⁺主要分布在PM₁₀中。3个点位PM₁₀和PM_2.5中的水溶性离子均表现为SO₄^2-、NH₄⁺、Ca²⁺浓度较大，F^-、NO₂^-较小，表明3个点位的污染源总体相同，且水溶性离子占PM₁₀、PM_2.5含量的比例达33.6%~48.1%。贵阳市城区大气中的SO₂转化率在5月、7月、10月较高，2月最低，主要是由于5月、7月、10月的高温、高湿、强辐射环境条件促进了SO₂向SO₄^2-的转化。阴阳离子平衡分析表明，贵阳市城区PM₁₀、PM_2.5呈现出偏碱性的特征。水溶性离子主成分分析表明，贵阳市城区PM₁₀中的水溶性离子主要来源于城市扬尘、生物质燃烧尘、煤烟尘、建筑尘以及二次粒子，PM_2.5中水溶性离子的来源与PM₁₀较为相似。     

长江集装箱港口岸线利用空间格局及其对资源环境的影响

长江岸线资源是沿江地区社会经济发展的重要支撑,同时其处于水陆交界地带有着无法替代的生态价值.通过遥感影像解译和相关数据资料汇总分析现代化航运组成之一的集装箱港口岸线利用格局,探究其对生态保护岸段的影响及成因,讨论如何合理组织港口岸线以实现绿色发展.长江集装箱港口岸线规模研究时段内大幅提升,上中下游分别形成各自较为密集的分布区域,集装箱港口更替以小型减量为主并将增量重心向大中型倾斜;港口岸线利用持续增长加速对保护岸段侵占,中小型港口为最主要占用类型,部分既有港口因所在城市大部分可利用岸段位于保护区内而留存;集装箱港口开发利用与保护间关系演变存在阶段性,岸线资源管理缺乏统筹协调,两者间冲突不可避免并已大量发生,但研究时段内港口扩张逐渐放缓、矛盾出现缓和,今后需更细致进行港口开发与岸线保护工作,提升综合管理能力.     

衡阳市区和衡山背景站臭氧浓度变化规律的对比分析

选取衡阳市区和衡山背景站臭氧自动监测数据,分析两地的臭氧污染特征。对空气质量的优良率情况、臭氧作为首要污染物的变化情况、臭氧浓度的日变化特征、典型时段的浓度变化特征、臭氧浓度的月际变化特征和臭氧与PM_(2.5)的关联情况等进行了分析。结果表明,多云及阴雨天气时,衡阳市区的臭氧浓度日变化幅度大于衡山背景站。夏季,衡阳市区和衡山背景站的臭氧浓度的日变化特征规律差异较大,臭氧浓度分布比较分散,前者为典型的单峰形,后者则波动平缓。冬季,日变化幅度不大,但衡阳市区的臭氧浓度明显低于衡山背景站。衡山背景站和衡阳市区的臭氧基本同步变化,但日均值高于衡阳市区。     

基于地理探测器的土壤重金属影响因子分析及其污染风险评价

地理探测器能快速定量化揭示驱动重金属含量影响因素的强度,这对于重金属空间预测模型构建变量的确定和土壤污染修复措施的精准实施具有重要意义。利用地理探测器模型,对5种土壤重金属元素Cu、Zn、Pb、Cr、Ni的空间分布和11种环境因子的交互作用进行定量评估,通过单因子指数法进行重庆市土壤重金属污染风险评价。结果表明:研究区内土壤Cu、Zn、Cr和Pb的平均含量是重庆市土壤背景值的1.3—1.4倍,Ni含量低于背景值;其中Cu、Pb达到重度污染水平,其余3种重金属为中度或轻度污染水平。5种重金属元素中Cu和Pb为高度变异(变异系数为0.57、0.4),Zn、Cr和Ni为中等变异(变异系数为0.22—0.29),且各重金属元素之间呈显著正相关性,表明研究区重金属富集受人为干扰影响较大,且污染具有复合性或同源性。地理探测器的因子探测发现高程、坡度和土壤类型对5种土壤重金属含量的解释力最显著,说明地势和土壤类型是土壤重金属含量分布差异的最主要影响因素。交互作用探测发现,高程与其他因子交互作用是重金属空间分异的主导因素,气候条件和土壤类型也是重要影响因子。土壤重金属空间分布是多种因素共同作用的结果,而高程、坡度和土壤类型具有较强的解释力,这些因子可作为土壤重金属含量空间预测模型的辅助变量,也可促进重金属污染治理措施的靶向实施。