Treatment of electroplating wastewater using electrocoagulation and integrated membrane.

Electroplating wastewater contains heavy metal ions and organic matter. These contaminants not only endanger the environment but also pose risks to human health. Despite the development of various treatment processes such as chemical precipitation MBR, electrocoagulation (EC) ceramic membrane (CM), coagulation ultrafiltration (UF) reverse osmosis (RO), and CM RO. These methods are only effective for low concentrations of heavy metals and struggle with high concentrations. To address the challenge of treating electroplating wastewater with high heavy metal content, this study focuses on the wastewater from Dongfang Aviation Machinery Processing Plant. It introduces an EC and integrated membrane (IM) treatment process for electroplating wastewater. The IM comprises microfiltration (MF) membrane, nanofiltration (NF) membrane, and RO membrane. Results indicated that under specific conditions, such as a pH of 8, current density of 5 A/dm2, electrode plate spacing of 2 cm, 35 min of electrolysis time, and influent pH of 10 for the IM, removal rates of Zn2+, Cu2+, Ni2+, and TCr in the wastewater exceeded 99%. The removal rates of chemical oxygen demand (COD), suspended solids (SS), total phosphorus (TP), total nitrogen (TN), and petroleum in wastewater exceed 97%. Following a continuous cleaning process, the membrane flux can consistently recover to over 94.3%.

How the implementation of internal carbon pricing impacts on carbon reduction: facilitating or hindering.

A growing number of companies are incorporating internal carbon pricing into their climate management strategies, making it one of the ways in which the private sector can combat carbon emissions and respond to the climate crisis. In this study, we used the synthetic control method in an attempt to discover whether the implementation of internal carbon pricing has an impact on the carbon reduction of typical firms at an individual level. As some of the firms cannot be properly fitted, statistical approaches were then applied to the S&P 500 constituent firms to test if there is any correlation between the emission cuts and internal carbon pricing. We also conducted a channel analysis. Through examining three possible channels, internal carbon pricing is found to affect firms' carbon reduction mainly through two channels, namely the level of energy intensity and R&D investments. Among them, the energy intensity plays a positive mediating role between emission reduction and internal carbon pricing. As to another channel, contrary to expectations, internal carbon pricing, to some extent, suppresses the R&D investments which will promote carbon emission reduction. That is, the size of R&D investments has masking effects in the relationship between emission cuts and internal carbon pricing. Our findings contribute to researches on the carbon pricing, emission reduction, and climate management efforts from the private sector and have implications for practices.