The environmental benefits of water recycling and reuse

Wastewater reclamation and reuse has been proved to be an effective way to relieve the fresh water crisis. However, toxic contaminants remaining in reclaimed water could lead to potential risk for reuse, and the conventional water quality standards have difficulty guaranteeing the safety of reclaimed water. Bioassays can vividly reflect the integrated biological effects of multiple toxic substances in water as a whole, and could be a powerful tool for evaluating the safety of reclaimed water. Therefore, in this study, the advantages and disadvantages of using bioassays for evaluating the safety of reclaimed water were compared with those of conventional water quality standards. Although bioassays have been widely used to describe the toxic effects of reclaimed water and treatment efficiency of reclamation techniques, a single bioassay cannot reflect the complex toxicity of reclaimed water, and a battery of bioassays involving multiple biological effects or in vitro tests with specific toxicity mechanisms would be recommended. Furthermore, in order to evaluate the safety of reclaimed water based on bioassay results, various methods including potential toxicology, the toxicity unit classification system, and a potential eco-toxic effects probe are summarized as well. Especially, some integrated ranking methods based on a bioassay battery involving multiple toxicity effects are recommended as useful tools for evaluating the safety of reclaimed water, which will benefit the promotion and guarantee the rapid development of the reclamation and reuse of wastewater.

Bioassay: A useful tool for evaluating reclaimed water safety

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9233172

Recent advances in aqueous virus removal technologies

Effects of chlorination and combined UV/Cl2 treatment on endotoxin activity and inhalation toxicity of lipopolysaccharide, gram-negative bacteria and reclaimed water.

Heterogeneity effects of nanoplastics and lead on zebrafish intestinal cells identified by single-cell sequencing.

The COVID-19 pandemic draws much attention to virus inactivation since the SARS-CoV-2 was detected in miscellaneous environments and the wastewater can be a potential transmitting pathway. UV irradiation, ozonation and chlorination are widely used disinfection processes in water treatment. In this review, the mechanisms and applications of three disinfection processes are introduced, and their inactivation effects on virus as well as other microorganisms are compared and discussed. The resistance of viruses to UV irradiation is generally stronger than that of bacteria. 4-log inactivation of bacteria can be easily obtained within a UV dose of 10 ​mJ/cm2. However, the doses to reach the same virus removal rate vary greatly from 10 to 140 ​mJ/cm2. The coronaviruses have even stronger UV resistance. Comparatively, ozonation and chlorination are effective methods to inactivate viruses, and the CT values of 4-log removal for most viruses concerned are lower than 1 ​mg·min/L and 10 ​mg·min/L, respectively. Protozoa, fungal spores and bacterial spores are more resistant to disinfection. Temperature, pH, organic matters, turbidity and other parameters all have influences on the disinfection. With a 10 ​°C decrease in temperature, the CT value required for certain removal rates doubles. Generally low pH promotes disinfection and high pH is against it. In drinking water and wastewater treatment process, the resistance properties of microorganisms and other influence parameters should be taken into consideration when choosing disinfection technologies.

The virus removal in UV irradiation, ozonation and chlorination

Effects of ozonation on the activity of endotoxin and its inhalation toxicity in reclaimed water.

TLR4-MyD88 signaling pathway is responsible for acute lung inflammation induced by reclaimed water.

Carbon dioxide is believed widely to be the major contributor to global warming. Policymakers worldwide are turning to tax policies in an effort to abate carbon emissions. China is the largest emitter of carbon emissions on our planet. The central government, as well as the local official, has introduced a series of environmental regulations, such as environmental protection tax and emissions trading system, to reduce carbon emissions and improve environmental quality. In the near future, the carbon emission tax is also expected to be implemented by the Chinese government. In order to analyze and predict the effect of the carbon emission tax on environmental and economic systems, we developed a four department dynamic stochastic general equilibrium model, which includes households, enterprises, the government, and the environment. The dynamic parameters were obtained using maximum likelihood estimation. In the comparative static-s analysis, we found that after the introduction of carbon emission tax, the level in environmental quality was substantially improved, whereas most economic variables were significantly reduced. Moreover, we used impulse responses functions to evaluate how one shock to the carbon emission tax affects the steady static values for these endogenous variables in our model. We found that the carbon emission tax shock has an instantaneous effect on the majority of economic variables, but it does not affect the environmental quality immediately. In addition, we tested the Porter hypothesis and found no evidence suggesting the statement regarding this hypothesis. Finally, we applied Bayesian estimation to assure our findings in this study, again.

/pdf/the-effect-of-carbon-emission-taxes-on-environmental-and-20uooukr.pdf

The Effect of Carbon Emission Taxes on Environmental and Economic Systems

Innovation, as a driving force to economic growth, has been referred to as an important development strategy by the central government of China. In order to improve the innovative capability of cities, Chinese officials started to construct innovation cities in 2008. Previous studies have investigated the ecological and economic effects of innovation city construction; however, the environmental effect of the project remains unclear. In this study, we constructed an annual panel of 285 cities in China, from 2007 to 2015, to assess the effect of innovation city construction on carbon emissions. Our baseline results are obtained from a difference-in-differences estimator, comparing cities with and without introducing innovation city construction, whose results show that innovation city construction reduces carbon emissions by about 2% on average. We found a similar effect of innovation city construction on carbon emissions when we controlled for the estimated propensity of a city to launch the innovation city construction based on a series of urban characteristics, such as gross regional product and population. We obtained comparable estimates when we used the propensity score as weights to balance urban characteristics between cities with and without launching the innovation city construction. Our results also show that innovation city construction has a larger effect on carbon emissions in western, poorer, and fewer population cities than in those with opposite characteristics. We found suggested the persistence of the effect that innovation city construction had on carbon emissions, implying that the Chinese government should encourage innovation to reduce carbon emissions. Besides, we performed a series of robustness tests, including the leave-one-city-out test, the bootstrapping test, and the permutation test, to illustrate the robustness of our results.

/pdf/the-effect-of-innovation-city-construction-on-carbon-1d2dblrf.pdf

Jiayang Kong

Papers

The virus removal in UV irradiation, ozonation and chlorination

Effects of ozonation on the activity of endotoxin and its inhalation toxicity in reclaimed water.

TLR4-MyD88 signaling pathway is responsible for acute lung inflammation induced by reclaimed water.

The Effect of Carbon Emission Taxes on Environmental and Economic Systems

The Effect of Innovation City Construction on Carbon Emissions in China