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.     

Assessment of deep aquifer groundwater quality in a geographically unique climatic region of Southern Western Ghats,India using water quality indices

Water quality index (WQI) models are generally used in hydrochemical studies to simplify complex data into single values to reflect the overall quality. In this study, deep groundwater quality in the Chittur and Palakkad Taluks of the Bharathapuzha river basin of Kerala, India, was assessed by employing the WQI method developed by the Canadian Council of Ministers of the Environment (CCME). The assessment of overall water quality is indispensable due to the specific characteristics of the study area, such as geography, climate, over-drafting, and prevalent agricultural practices. Forty representative samples were collected from the study area for monsoon (MON) and pre-monsoon (PRM) seasons. The results showed a general increase of contents from MON to PRM. The major cations were spread in the order Ca²⁺>Na+>Mg²⁺>K⁺ and the anions HCO₃⁻>Cl⁻>CO₃²⁻ based on their relative abundance. Among various parameters analysed, alkalinity and bicarbonate levels during MON were comparatively high, which is indicative of carbonate weathering, and 90% of the samples failed to meet the World Health Organization (WHO, 2017)/Bureau of Indian Standards (BIS, 2012) drinking water guidelines. The CCME WQI analysis revealed that nearly 50% of the samples during each season represented good and excellent categories. The samples in the poor category comprised 10% in MON and 15% in PRM. The overall WQI exhibited 15% of poor category samples as well. The spatial depiction of CCME WQI classes helped to expose zones of degraded quality in the centre to eastward parts. The spatial and temporal variations of CCME WQI classes and different physicochemical attributes indicated the influence of common factors attributing to the deep groundwater quality. The study also revealed inland salinity at Kolluparamba and Peruvamba stations, where agricultural activities were rampant with poor surface water irrigation.     

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。     

北太平洋柔鱼渔场时空分布与海洋环境要素的研究

根据2010 年7~9月和2011年7~10月“舟渔1301#” 2个航次的北太平洋柔鱼渔场海上调查资料,利用渔获生产数据?海况天气数据以及同期的卫星遥感获取的海表面温度(SST) ?海表盐度(SSS)及叶绿素a (Chl-a)浓度和海流等数据,分析柔鱼的中心渔场分布与海洋环境的变动关系.研究结果显示:整个调查期间渔获频次在SST和Chl-a因子上均呈正态分布,渔场高产的最适SST范围为18~20℃, 最适SSS范围为33.60‰~34.80‰, 最适Chl-a浓度范围为0.08~0.24mg/m3,其中SST与柔鱼渔场之间有较好的匹配关系,中心渔场通常位于18~20℃的等温线附近,且位置一般出现在冷水团和暖水团交汇区的冷水团一侧;中心渔场位于亲潮和黑潮交汇混合区的向北一侧,离交汇地带的距离较近,而且随着时间的推移,渔汛期间中心渔场的位置逐步往其向西北方向移动.总体上多个环境因子皆可作为确定潜在中心渔场的指标,但以海表水温为最佳,另外辅助寒?暖流的交汇情况以及Chl-a浓度?天气海况等因素来综合分析,判断渔场的中心位置会更准确.     

Effect of six kinds of scale inhibitors on calcium carbonate precipitation in high salinity wastewater at high temperatures

Precipitation of calcium carbonate(Ca CO3) scale on heat transfer surfaces is a serious and expensive problem widely occurring in numerous industrial processes. In this study, we compared the scale inhibition effect of six kinds of commercial scale inhibitors and screened out the best one(scale inhibitor SQ-1211) to investigate its scale inhibition performance in highly saline conditions at high temperature through static scale inhibition tests. The influences of scale inhibitor dosage, temperature, heating time and p H on the inhibition efficiency of the optimal scale inhibitor were investigated. The morphologies and crystal structures of the precipitates were characterized by Scanning Electron Microscopy and X-ray Diffraction analysis. Results showed that the scale inhibition efficiency of the optimal scale inhibitor decreased with the increase of the reaction temperature. When the concentration of Ca2+was 1600 mg/L, the scale inhibition rate could reach 90.7% at 80°C at p H 8. The optimal scale inhibitor could effectively retard scaling at high temperature. In the presence of the optimal scale inhibitor, the main crystal structure of Ca CO3 changed from calcite to aragonite.     

Climate change and soil salinity: The case of coastal Bangladesh

This paper estimates location-specific soil salinity in coastal Bangladesh for 2050. The analysis was conducted in two stages: First, changes in soil salinity for the period 2001–2009 were assessed using information recorded at 41 soil monitoring stations by the Soil Research Development Institute. Using these data, a spatial econometric model was estimated linking soil salinity with the salinity of nearby rivers, land elevation, temperature, and rainfall. Second, future soil salinity for 69 coastal sub-districts was projected from climate-induced changes in river salinity and projections of rainfall and temperature based on time trends for 20 Bangladesh Meteorological Department weather stations in the coastal region. The findings indicate that climate change poses a major soil salinization risk in coastal Bangladesh. Across 41 monitoring stations, the annual median projected change in soil salinity is 39 % by 2050. Above the median, 25 % of all stations have projected changes of 51 % or higher.     

采用水解酸化-复合好氧处理制药工业废水的工艺评价

以制药工业综合废水处理为例对其采用的两级水解酸化复合好氧工艺的处理效果进行评估。按常规指标进行评估,该工艺对于制药综合废水的处理效果达到了设计目的,COD去除率可达到78.2%以上,NH+4-N的去除率达到99.3%,出水质量基本满足"污水综合排放标准(GB8978-1996)"二级标准和"辽宁省污水综合排放标准(DB21.1627-2008)";急性毒性的检测表明,经过该工艺处理后出水为低毒性;三维荧光谱分析(EEM)表明,制药综合废水经生物处理后的可溶性有机物中仍然存在难降解物质,建议增加物化处理以提高处理效果;并且制药废水经处理后的出水中的盐度对排入的生态系统存在风险,建议纳入排放标准以加强管理。     

Effects of salinity on soil bacterial and archaeal community in estuarine wetlands and its implications for carbon sequestration: verification in the Yellow River Delta

Soils from two typical tidal salt marshes with varied salinity in the Yellow River Delta wetland were analysed to determine possible effects of salinity on soil carbon sequestration through changes in soil microbiology. The mean soil respiration (SR) of the salt water–fresh water mixing zone (MZ) was 2.89 times higher than that of the coastal zone (CZ) (4.73 and 1.63?μmol?m^?2?s^?1, respectively, p?Pseudomonas sp. and Limnobacter sp. that might have led to its higher dehydrogenase activity and respiratory rates. Additionally, the CZ possessed more Halobacteria and Thaumarchaeota with the ability to fix CO₂ than the MZ. Significantly lower soil salinity in MZ (4.25?g?kg^?1) was suitable for β-Proteobacteria, but detrimental for Halobacteria compared with CZ (7.09?g?kg^?1, p?相似文献   

Phytoavailability and potential transfer of Pb from a salt-affected soil to Atriplex verucifera,Salicornia europaea and Chenopodium album

The phytoavailability and potential transfer of Pb to Atriplex verucifera, Salicornia europaea and Chenopodium album in two calcareous soils with different salinity/sodicity were compared. The soils were spiked with 0, 250, 500 and 1000 mg Pb kg^?1 soil. Plant shoots were harvested and analysed for total Pb after they had been grown in the contaminated soils. Visual MINTEQ 3.0 was used to calculate the speciation of soluble Pb in the experimental soils. Results showed that although the concentrations of 1 M NH₄NO₃-extractable Pb were relatively similar, speciation of Pb in the soils were not the same. Salicornia europea was found to be the most salinity/sodicity-tolerant plant. When the plants were grown in non-saline soil, the Pb tolerance of the three plants was as follows: A. verucifera > C. album >S. europea, whereas in saline (sodic) soil, Pb tolerance was in the order S. europea > C. album > A. verucifera. Lead phytotoxicity to A. verucifera and C. album was higher in the saline soil, whereas for S. europea, Pb toxicity was higher in the non-saline soil. It could be concluded that the phytoavailability of Pb and its interactions with plants are widely dependent on soil salinity level and type of plant.     

Hot,Salty Water: A Confluence of Issues in Managing Stormwater Runoff for Urban Streams

Research increasingly highlights cause and effect relationships between urbanization and stream conditions are complex and highly variable across physical and biological regions. Research also demonstrates stormwater runoff is a key causal agent in altering stream conditions in urban settings. More specifically, thermal pollution and high salt levels are two consequences of urbanization and subsequent runoff. This study describes a demonstration model populated with data from a high gradient headwaters stream. The model was designed to explain surface water‐groundwater dynamics related to salinity and thermal pollution. Modeled scenarios show long‐term additive impacts from salt application and suggest reducing flow rates, as stormwater management practices are typically designed to do, have the potential to greatly reduce salt concentrations and simultaneously reduce thermal pollution. This demonstration model offers planners and managers reason to be confident that stormwater management efforts can have positive impacts.