Optimization of a Photo‐assisted Fenton Oxidation Process: A Statistical Model for MDF Effluent Treatment

In the present study, the effects of initial COD (chemical oxygen demand), initial pH, Fe²⁺/H₂O₂ molar ratio and UV contact time on COD removal from medium density fiberboard (MDF) wastewater using photo‐assisted Fenton oxidation treatment were investigated. In order to optimize the removal efficiency, batch operations were carried out. The influence of the aforementioned parameters on COD removal efficiency was studied using response surface methodology (RSM). The optimal conditions for maximum COD removal efficiency from MDF wastewater under experimental conditions were obtained at initial COD of 4000 mg/L, Fe²⁺/H₂O₂ molar ratio of 0.11, initial solution pH of 6.5 and UV contact time of 70 min. The obtained results for maximum COD removal efficiency of 96% revealed that photo‐assisted Fenton oxidation is very effective for treating MDF wastewater.     

Effects of vegetation and sewage load on mangrove crab condition using experimental mesocosms

Constructed wetlands, especially mangroves, have been studied for their usefulness in sewage treatment but the effects of mangrove vegetation and a sewage load on mangrove macrofauna have been given little attention. Ocypodid crabs are important components of mangrove forests and constitute good bioindicators of the functioning of the ecosystem as a whole. In constructed mangrove mesocosms, three vegetation treatments (bare substratum, and Avicennia marina and Rhizophora mucronata seedlings) were subjected to 0, 20, 60 and 100% sewage loads from a nearby hotel. The physiological condition of introduced Uca annulipes and Uca inversa was evaluated in terms of their RNA/DNA ratio after one, five and twelve months, and used as an indicator of ecological function in the system. Crab condition in 0% sewage load was similar to that of wild crabs throughout, suggesting no significant effects of the mesocosms on their RNA/DNA ratio. Overall, both species coped well with the administered sewage loads, suggesting good ecological function in the system. Both species manifested similar patterns in RNA/DNA ratio, being more affected by seasonal fluctuations than by sewage load and vegetation presence and type. Higher RNA/DNA ratios were recorded in the long compared to the short rainy season. Sewage enhanced crab condition in the bare substratum and R. mucronata treatments, especially after one year, probably as a result of enhanced food availability. Uca inversa may be more sensitive to sewage pollution than U. annulipes. In A. marina, no difference in crab condition was observed between sewage loads, and this mangrove yielded the best reduction in sewage impacts. Our results support the usefulness of constructed mangrove areas in sewage treatment, especially if planted with A. marina and inhabited by physiologically healthy ocypodid crabs to enhance the system's performance.     

异波折板多段两相厌氧城市污水处理工艺试验研究

提出了异波折板多段两相厌氧城市污水处理工艺。通过反应器内异波折板的结构设计、液相流速设计和系统内生物相的分段调控,在提高传质效率的同时,使不同种群微生物的生化活性得到明显改善,有机污染物去除效率显著提高。实验结果表明,当水力停留时间大于10 h时,COD的去除率可达90%以上,而且受温度影响很小。     

Modified column flotation of adsorbing iron hydroxide colloidal precipitates

A promising technique for the removal of heavy metal ions from wastewater streams involved firstly the ions adsorption on a colloidal precipitate (carrier) and then the separation of the loaded flocs (coagula) by a modified column flotation. Here, the effluent feed and the carrier (ferric hydroxide) enter smoothly by the top of the column through a special diffuser, in counter current with rising bubbles (100–600 μm diameter) generated by using recycled water, surfactant and air suction through a venturi. High separation values of the column flotation of the carrier precipitates were achieved, despite the high superficial flow rate and the high Fe^+ 3 concentration utilized (> 60 mg L^− 1 Fe). No rupture of colloidal carrier aggregates was observed and a low split was ensured by monitoring the concentrate (floated product) flow rate. Results indicated that best separation was attained by controlling the medium pH (for best heavy metal ion adsorption onto the carrier), followed by sodium oleate, used as “collector” and optimizing operating parameters (conditioning, flow rates, etc.). The column throughput reached 43 m h^− 1 (m³ m^− 2 h^− 1), which is about 4 times the normal capacity of DAF-dissolved air flotation unit, the most used floater in wastewater treatment. Various metals (Cu, Ni, Pb, etc.) and molybdate ions present in synthetic and real effluent were successfully removed based on this colloidal adsorbing flotation principle. The process was also applied in a pilot scale to treat an industrial electroplating wastewater. Most of toxic metals (Cu, Ni and Zn) were reduced from initial concentrations of about of 2 to 10 mg L^− 1, to below 0.5 to 1.0 mg L^− 1, meeting local municipal discharge limits (but Cd ions). It is believed that flotation separation using medium-sized bubbles has great potential as a clean water and wastewater treatment technology.     

纳米 Fe2O3-SnO2 光催化降解海水养殖废水中的氨氮

通过共沉淀法制备纳米Fe_2O_3-SnO_2光催化剂,采用XRD、SEM等测试手段对其进行形貌、物象、粒径一系列的表征,研究结果显示制得的催化剂仍保持纯SnO_2四方金红石型结构.研究了Fe_2O_3-SnO_2光催化剂投加量、Fe_2O_3与SnO_2物质的量比、煅烧温度、煅烧时间、氨氮初始浓度、p H值、H2O2浓度以及光照反应时间等因素对海水养殖废水中氨氮降解效率的影响.在紫外光照射下进行正交实验,确定最优化反应条件:催化剂投加量为0.4 g/dm3,煅烧时间为3 h,物质的量比为1∶2,氨氮初始含量为50 mg/dm3,光照反应时间为2 h.这5个因素对Fe_2O_3-SnO_2光催化氧化速率影响的大小程度依次为:Fe_2O_3与SnO_2物质的量比煅烧时间Fe_2O_3-SnO_2光催化剂投加量氨氮初始浓度光照时间.氨氮去除率可以达到85.1%,相同条件可见光下也可达到82.3%.     

胜利油田采油污水综合特征及利用评价

胜利油田作为我国石油的重要赋存区,其地热资源也相当丰富。在节能减排的背景下,采油产生的污水由于其相对较高的温度,除了用于回注开采层提高石油采收率,还能用于供暖、洗浴等。通过采集胜利油田济阳坳陷探区19个典型采油联合站分离出的采油污水,分析其水化学组分和微量元素,总结了采油污水的基本水化学特征以及腐蚀性和结垢性趋势。研究结果表明,本次采集的采油污水属于咸水-卤水,矿化度最高可达59.7gL-1,其中锂和锶的含量达到了作为矿水的要求。综合腐蚀性系数和拉申指数评价方法得出采油污水属于强腐蚀性水。结垢性评价结果表明,这些采油污水不会形成碳酸钙垢,也不具备二氧化硅的结垢条件,仅滨南和河口采油厂采油污水有硫酸钙结垢的可能性,综合利用前需要及时预防和处理。采油污水可以用于开采层回注、供暖、洗浴、温室大棚和水产养殖等,一方面可以减少环境污染,另一方面还能改善能源结构,具有良好的社会和经济效益。在综合利用采油污水时,需要考虑其腐蚀性和结垢性,选择合适的预处理方式及管道。     

Kinetic Modelling of the Removal of Seven Common Pollutants in Subsurface Flow Constructed Wetlands

The main removal mechanisms for the degradations of seven pollutants in wastewater treatment wetlands were analysed, and a mathematical model was established to quantify the removal of each pollutant, based on its main removal mechanisms. Subsurface horizontal flow wetlands were treated as a series of continuous stirred - tank reactors (CSTRs). Kinetic models for the removal of biochemical oxygen demand, chemical oxygen demand, ammonia, total nitrogen and faecal coliforms were established by combining Monod or first - order kinetics with CSTR assumptions. These tentative models account for a wide range of factors that affect wetland performance, but the models have not been proven by ex periment data. Depending on the derivation of various coefficients in the models and verification by actual performance data, this study may provide a starting point for an integrated pollutant removal model to be developed, and experimen tally verified, thereby making a step forward from the current greenbox' approach of wetland design.     

柱层累托石材料对有机废水的处理及效果评价

就使用柱层累托石材料对有机废水处理的实验研究进行讨论。采用累托石材料，在用量为15kg/t时，加入用量为4kg/t的还原剂FE，废水中COD去除率达70%；如果再用累托石进行二次吸附，其COD去除率达92%；处理水COD值降为96mg/L，达到GB8978-1996一级排放标准，同时实验了累托石的再生利用效果。     

Intra-annual variability of urban effects on streamflow

While considerable research has established the impacts of urbanization on streamflow, there has been little emphasis on how intra-annual variations in streamflow can deepen the understanding of hydrological processes in urban watersheds. This study fills this critical research gap by examining, at the monthly scale, correlations between land-cover and streamflow, differences in streamflow metrics between urban and rural watersheds, and the potential for the inflow and infiltration (I&I) of extraneous water into sewers to reduce streamflow. We use data from 90 watersheds in the Atlanta, GA region over the 2013–2019 period to accomplish our objectives. Similar to other urban areas in temperate climates, Atlanta has a soil-water surplus in winter and a soil-water deficit in summer. Our results show urban watersheds have less streamflow seasonality than do rural watersheds. Compared to rural watersheds, urban watersheds have a much larger frequency of high-flow days during July–October. This is caused by increased impervious cover decreasing the importance of antecedent soil moisture in producing runoff. Urban watersheds have lower baseflows than rural watersheds during December–April but have baseflows equal to or larger than baseflows in rural watersheds during July–October. Intra-annual variations in effluent data from wastewater treatment plants provide evidence that I&I is a major cause of the relatively low baseflows during December–April. The relatively high baseflows in urban watersheds during July–October are likely caused by reduced evapotranspiration and the inflow of municipal water. The above seasonal aspects of urban effects on streamflow should be applicable to most urban watersheds with temperate climates.     

中山市河涌水体及污水处理厂中 合成麝香的分布规律

对中山市5个区域的48条主要河涌水体与2间污水处理厂各工艺流程水体进行样品采集,运用固相微萃取进行前处理并结合气相色谱—质谱联用技术,检测各样品中佳乐麝香、吐纳麝香和酮麝香这3种合成麝香的含量,并分析其分布特征以及探讨污水处理厂处理工艺中合成麝香的浓度变化规律。结果表明：1）合成麝香已经普遍存在于中山市的河涌水体中。中山市西部地区和南部地区的河涌水体中合成麝香总含量相对其他区域最低,中部地区河涌水体中合成麝香含量亦较低。2）中山市雁企涌和魁魁涌等28条河涌水体中的主要合成麝香为佳乐麝香,一埒涌和乌沙涌等13条河涌水体的主要合成麝香为酮麝香,仅有苏埒涌和石军涌等7条河涌水体的主要合成麝香为佳乐麝香和酮麝香这2种合成麝香。3）氧化沟和A2/O工艺均能对合成麝香产生一定的去除效果。污水处理厂A对佳乐麝香、吐纳麝香和酮麝香的去除率分别为86.94%、72.15%和89.36%;而污水处理厂B对以上3种合成麝香的去除率分别为82.09%、85.73%和87.90%。4）2间污水处理厂的二沉池以及污水处理厂A的紫外消毒亦可对合成麝香产生进一步的去除效果;2间污水处理厂均能对酮麝香产生比佳乐麝香和吐纳麝香更高的去除率。