Process evaluation of urban river replenished with reclaimed water from a wastewater treatment plant based on the risk of algal bloom and comprehensive acute toxicity

Municipal wastewater reuse has an important role to play with scarce water resources and serious water pollution. However, the impact of reclaimed water on the aquatic ecology and organisms of the receiving water needs to be assessed. This study investigated one ecological restoration project of an urban river replenished with reclaimed water, and evaluated the risk of algal bloom and acute biological toxicity in the river. Results showed that the concentrations of permanganate index and ammonia nitrogen in the river could stably remain below the standard values, the concentrations of total phosphorus were high and most of the monitoring values were between 0.42 and 0.86 mg/L. The content of chlorophyll a was relatively lower, ranging from 0.06 to 0.10 mg/m3. The maximum value of Fv/Fm was 0.42, which was lower than the algal bloom prediction threshold of 0.63. Moreover, the results of luminescence inhibition rate on luminescent bacteria showed that the reclaimed water did not cause significant biological toxicity to the aquatic ecology. The study suggested that implementing urban reclaimed water reuse projects requires a series of ecological purification and restoration technologies in the receiving water, which can effectively guarantee the stability of water quality and the safety of water ecological environment.

How much do the conventional parameters contribute to the biological toxicity of surface water in different types of villages?

Background In rural areas, the surface water quality is seriously threatened by pollution from agriculture, breeding, industrial and tourism activities. Even though many strategies and programs were launched for rural environment management, it is challenging to tackle the serious surface water pollution in villages. Since pollution status varies with the type of villages, there is no single parameter that defines environment quality completely. Until recently, most of rural surface water quality monitoring programs focus only on the conventional parameters, while can these conventional parameters reflect comprehensive status of water quality? To study how much the conventional parameters contribute to biological toxicity of surface water in villages, the in situ parameters of pH, DO, EC, ORP, laboratorial parameters of COD, TN, NO3−-N, NO2−-N, NH4+-N, TP, and PO43−-P and acute toxicity were analyzed for the surface water samples those were collected from six types of villages, named breeding, agricultural, handicraft, industrial, agricultural and breeding, and tourism. The correlation analysis was applied to establish the linkages and contributions of each parameter. Results The results showed that all detected surface waters were alkaline, and the concentration of TN and most of COD concentrations in all six types of villages were higher than the Class V limits specified in environmental quality standards for surface water (GB3838-2002). Pearson’s correlation analysis showed that significantly positive correlations were found for the acute toxicity effects and laboratorial parameters of NO2−-N, NH4+-N and PO43−-P in agricultural villages, and negative correlations were found for the acute toxicity effects and laboratorial parameters of TN and NO3−-N. No significant correlation was observed in breeding villages and industrial villages. Conclusion The problems of nitrogen pollution and aerobic pollution are still serious in villages, and more attention should be paid in further rural environment management. NH4+-N could contribute to the acute toxicity of surface water in the most of investigated villages, while no significant correlation was observed between acute toxicity and conventional parameters in industrial villages and tourism villages. Environmental monitoring programs focusing just on the classical conventional parameters are far from sufficient, since the main toxic contributors are quite different in diverse villages. The outcomes of the present study contribute to demonstrate the performance and usefulness of bioanalytical techniques for water quality assessment.

Development and Application of a Novel Green Water-Based Drilling Fluid

In response to the technical and environmental protection requirements of water-based drilling fluids, this study independently developed a series of green supporting treatment agents for water-based drilling fluids such as the green loss reducer HB-1, green inhibitor HB-2, and green lubricant HB-3, etc., and proposed a green water-based drilling fluid system (HBDF) with good comprehensive performance. The proposed system has a heat resistance of 150°C, a HTHP (high temperature and high pressure) filtrate loss of 12 mL, a biological toxicity EC50 value greater than 105 mg/L, and a biodegradability BOD5/CODCr value of 16.2%. Now the developed HBDF system has been applied in more than 10 wells in SL oilfield, and the field application results show that the proposed HBDF system has stable rheological and filtrate loss performance, good anti-pollution ability, and easy and simple maintenance operations; after drilling, the biological toxicity of the drilling fluids can meet the environmental protection requirements, which has provided a technical reference for the research of green drilling fluids and the green development of SL Oilfield.

Effect of solvation on the synthesis of MOFs-based micro/nanorobots and its targeted-therapy applications

Magnetically-driven mobile micro/nanorobots have a significant influence on the application and development of intelligent targeted drug delivery. However, the potential risk of biological toxicity is one of the major main...

A novel coumarin-based colorimetric and fluorescent probe for detecting increasing concentrations of Hg2+in vitro and in vivo

Mercury has complex biological toxicity and can cause a variety of physiological diseases and even death, so it is of great importance to develop novel strategies for detecting trace mercury in environmental and biological samples.