聚合氯化铝铁的形态分布对微污染源水混凝效果的影响

针对微污染源水中浊度、叶绿素a等的强化去除问题,研究了碱化度、铝铁比和加碱方式等对聚合氯化铝铁形态分布的影响,并考察了形态分布与混凝除污效率和混凝沉淀出水中残铝浓度的关系.结果表明:在铁摩尔分数一定时,混凝剂中单体、中等聚合物和无定形凝胶含量与碱化度存在线性相关性,并推导出中等聚合物含量的计算公式;在碱化度一定时,混凝剂中单体、中等聚合物和无定形凝胶含量与铁摩尔分数也存在线性相关性;增加碱化度或降低铁摩尔分数,可以增加中等聚合物含量、降低单体含量,从而影响混凝除污效率和混凝沉淀后出水中残铝浓度.混凝实验结果表明,混凝过程中叶绿素a去除率和浊度去除率均与混凝剂中中等聚合物含量存在线性相关性,但两者相关系数不同.混凝沉淀后出水中残铝浓度与混凝剂中单体含量存在线性相关性.因此,预聚合的无机高分子混凝剂对提高混凝过程中的除浊、除藻效率,降低混凝沉淀后出水中残铝浓度具有重要的意义.     

铁离子对滇池藻类生长的影响

有关氮、磷对滇池藻类生长的影响研究已有大量的报道.但关于铁离子对滇池藻类影响的研究还未见报道.以滇池藻样为对象,实验了不同铁离子浓度对滇池藻类生长的影响.结果表明,不同浓度范围铁离子对滇池藻类光合作用的促进或抑制是影响其生长的最主要因素.实验结果提示, 在控制湖泊藻类生长时,除了要注意控制氮、磷之外,还应考虑铁离子对藻类生长的影响.     

Microbial Removal of Arsenic

Bangladesh is currently the subject of the world's largest mass arsenic poisoning in history. Groundwater throughout Bangladesh and West Bengal is contaminated with naturally occurring arsenic from the alluvial and deltaic sediments that form the region's aquifers. It has been estimated that 75 million people are at risk of developing health effects associated with the ingestion of arsenic. This project focuses on the use of microorganisms such as bacteria and algae to remove arsenic from water. Arsenic in the arsenite form was used in the studies. Experiments were conducted with a common alga and wastewater bacteria. A common green algae Scenedesmus abundans was used for determining arsenic uptake in batch experiments. Results of the experiments indicated that the algae biosorption could be modeled by the conventional Langmuir isotherm model. Algae morphology studies indicated that the algae cells were impacted due to the presence of arsenic as evidenced by clumping or loss of cell clusters. The wastewater bacteria also were capable of high percent of arsenic removal. Results indicate that microbial uptake of arsenic may be a viable method of pretreatment of arsenic contaminated water. However algae and sludge disposal would pose a problem and will have to be dealt with accordingly.     

Optimization and modeling of coagulation-flocculation to remove algae and organic matter from surface water by response surface methodology

Charge neutralization and sweep flocculation were the major mechanisms. Effect of process parameters was investigated. Optimal coagulation conditions were studied by response surface methodology. ANN models presented more robust and accurate prediction than RSM. Seasonal algal blooms of Lake Yangcheng highlight the necessity to develop an effective and optimal water treatment process to enhance the removal of algae and dissolved organic matter (DOM). In the present study, the coagulation performance for the removal of algae, turbidity, dissolved organic carbon (DOC) and ultraviolet absorbance at 254 nm (UV₂₅₄) was investigated systematically by central composite design (CCD) using response surface methodology (RSM). The regression models were developed to illustrate the relationships between coagulation performance and experimental variables. Analysis of variance (ANOVA) was performed to test the significance of the response surface models. It can be concluded that the major mechanisms of coagulation to remove algae and DOM were charge neutralization and sweep flocculation at a pH range of 4.66–6.34. The optimal coagulation conditions with coagulant dosage of 7.57 mg Al/L, pH of 5.42 and initial algal cell density of 3.83 × 10⁶ cell/mL led to removal of 96.76%, 97.64%, 40.23% and 30.12% in term of cell density, turbidity, DOC and UV₂₅₄ absorbance, respectively, which were in good agreement with the validation experimental results. A comparison between the modeling results derived through both ANOVA and artificial neural networks (ANN) based on experimental data showed a high correlation coefficient, which indicated that the models were significant and fitted well with experimental results. The results proposed a valuable reference for the treatment of algae-laden surface water in practical application by the optimal coagulation-flocculation process.     

引滦河道中水质偏碱的起因研究

过分析揭示引滦河道pH值偏高的主要区域在于桥水库内,并分别从引滦河道流域内的岩石、土壤对地面水中溶质的影响、地下水运移及地面水中浮游植物的光合作用对水体pH值的影响等几方面寻找原因。经研究确定水体中藻类的光合作用是pH升高的主要原因。水中较高的氮、磷使藻类大量繁殖,而藻类在光合作用过程中,吸收二氧化碳,放出氧气,从而影响水中HCO-₃,CO₂和OH-的平衡,进而导致水体中pH升高。      

Cost-Effective Control of Interdependent Water Pollutants

Excess nutrient loads to coastal waters lead to increased production of algae, which when decaying cause oxygen depletion in bottom sediments, which in turn leads to major changes in marine ecosystems. A cost-minimization model was investigated in which nitrogen and phosphorus were assumed to interact with respect to algae production. It was investigated under what conditions only a single nutrient should be decreased and when it is cost-effective to decrease both nutrients. The model was applied to the Baltic Proper, which is the largest of the seven major basins in the Baltic Sea. Results showed that the stringency of the environmental target, as well as assumptions regarding substitutability between nutrients, are important factors to determine the nutrient on which to focus. Uniform decrease rates for emissions are often used in international agreements, and the results of this model showed that the costs of making such proportional decreases could be substantial.     

Algae (Raphidocelis subcapitata) mitigate combined toxicity of microplastic and lead on Ceriodaphnia dubia

• Micro-plastics (MPs) significantly increase Pb toxicity. • Algae reduce the combined toxicity of MP and Pb. • The toxicity increase comes from high soluble Pb and MP-Pb uptake. • The toxicity reduction might come from energy related pathway. Microplastics (MPs) have been recognized as a new class of emerging contaminants in recent years. They not only directly impact aquatic organisms, but also indirectly impact these organisms by interacting with background toxins in the environment. Moreover, under realistic environmental conditions, algae, a natural food for aquatic organisms, may alter the toxicity pattern related to MPs. In this research, we first examined the toxicity of MPs alone, and their effect on the toxicity of lead (Pb) on Ceriodaphnia dubia (C. dubia), a model aquatic organism for toxicity survey. Then, we investigated the effect of algae on the combined toxicity of MPs and Pb. We observed that, MPs significantly increased Pb toxicity, which was related to the increase in soluble Pb concentration and the intake of Pb-loaded MPs, both of which increased the accumulation of Pb in C. dubia. The presence of algae mitigated the combined toxicity of MPs and Pb, although algae alone increased Pb accumulation. Therefore, the toxicity mitigation through algae uptake came from mechanisms other than Pb accumulation, which will need further investigation.     

Synthesis and use of a catalyst in the production of biodiesel from Pongamia pinnata seed oil with dimethyl carbonate

The preparation of sodium methoxide-treated algae catalysts and their activity in the transesterification of Pongamia pinnata seed oil by dimethyl carbonate were investigated. We also investigated the effect of the sodium methoxide-treated algae catalyst on the biodiesel yield. The development of sodium methoxide-treated algae catalysts can overcome most problems associated with dissolution in dimethyl carbonate. The products were analyzed using gas chromatography-mass spectroscopy to identify the fatty acid methyl esters in the biodiesel produced. The molar ratio of Pongamia pinnata seed oil to dimethyl carbonate in transesterification in the presence of the sodium methoxide-treated algae catalyst was observed to play a substantial role in this study, wherein the Pongamia pinnata seed oil conversion increased with increasing catalyst concentration. The highest percent conversion rate was 97%. With intense research focus and development, an ideal catalyst can indeed be developed for optimal biodiesel production that is both economically feasible and environmentally benign.     

"去藻247"在除藻过程中对水体中氮磷的影响

随着目前水体藻类富营养化日益严重,国内外针对藻类的去除技术可分为物理、化学、生物法.实验采用国外引进的"去藻247"作为除藻剂,通过对滇池藻类去除效果进行试验和分析,研究"去藻247"中生物Cu2 通过改变水体中氮磷比例以及氮磷浓度的变化,以达到除藻的目的.结果表明,降低TP的浓度更易加大藻类的去除率,并且,其去除率随着藻类厚度(3～15 mm)的增加而提高,说明了"去藻247"具有一定的生物稳定性.     

藻类固定化技术在环境领域中的应用

在近年来，藻类固定化技术在环境领域中的应用逐渐得到重视，通过全面调研８０年代以来１００多篇文献后，文章精辟地综述了藻类固定化技术及其在污染治理和环境监测中的应用和发展趋势，以及国内的研究成果。