Chlorine and Chlorinated Compounds Removal from Industrial Wastewater Discharges: A Review

Adsorption techniques for industrial wastewater treatment rich in heavy metals and aqueous solutions of water-soluble such as Cl−, F−, HCO3−, NO3−, SO2−4, and PO3−, often include technologies for toxicity removals. The recent advancement and technical applicability in the treatment of chlorine and chlorinated compounds from industrial wastewater are reviewed in this article. Chlorine and chlorinated compounds are among the common discharged constituents from numerous industries. They can be carcinogenic or naturally toxic and can pose issues to aquatic ecosystems and human beings. Thus, elimination of chlorides and chlorinated compounds from water or wastewater is inevitable to get rid of the problem. Several techniques are being applied for the reduction of chlorine and chlorinated compounds in water. These include biodegradation, photochemical, adsorption, chemical, electrochemical, photo-electrochemical, membrane, supercritical extraction and catalytic method. Chlorine can react with various organic and inorganic micro-pollutants. However, the potential reactivity of chlorine for specific compounds is small, and only minor variations in the structure of the parent compound are anticipated in the water treatment process under typical conditions. This paper reviews different techniques and aspects related to chlorine removal, the types of chlorine species in solution and their catalyst, chlorine fate and transport into the environment, electrochemical techniques for de-chlorination of water, kinetics, mechanisms of reduction of chlorinated compounds, and kinetics of the electrochemical reaction of chlorine compounds. Keywords: Industrial waste, Kinetics, Wastewater, Water purification

The effect of groundwater petroleum hydrocarbons contaminants on chlorine removal in Basra city (south of Iraq): An application of mixed technology of permeable reactive barrier

Petroleum hydrocarbon contaminants in groundwater are among the most impactful environmental problems in oil production in southern Iraq, especially Basra city. Petroleum hydrocarbon contaminants affect related projects surrounding the primary pollution site. Benzene, toluene, and dimethylbenzene are the most toxic pollutants affecting the removal of perchloroethene (Cl2C=CCl2) and trichloroethene (C2HCl3) in groundwater. These pollutants have high solubility in water, leading to their transport over long distances in groundwater and difficult removal. The influence of petroleum hydrocarbons on the chlorine removal of perchloroethene and trichloroethene was studied using a polytetrafluorethylene column packed with zero-valent iron (ZVI). Batch experiments were implemented to investigate the equilibrium supply of mixtures between the aqueous and solid stages in packed column systems. It was designated using the Freundlich isotherm expression, and the result showed that R2 was greater than 0.97 for benzene, toluene, and xylene. The column study noted that the reaction constant was decreased in all columns by approximately 48 % when the pore volume was between 50 and 205, which reflects the dechlorination priority of P-CE over T-CE. These findings indicate that benzene and toluene are more effective for adsorption on the ZVI particle surfaces owing to disparate influences.

Effect of the Incorporation of Biomass in the Carbonization of Waste Electrical and Electronic Equipment

The behavior of chars from the carbonization process were studied when the lignocellulosic biomass was incorporated into the waste of electrical and electronic equipment for chlorine removal. Tests were performed at 300°C with a heating rate of 15°C/min and residence time of 60 min. Compositions studied had 100, 75, 50, 25 and 0% of waste electrical and electronic equipment (WEEE) in the mixtures. The composition of 50% WEEE with 50% lignocellulosic biomass presented the best char properties, having an increment of the calorific value in 5.5% relative to the initial value, and chlorine removal of 23.4% when compared to the forestry biomass.

Effect of cations on the removal rate of chloride ions and mechanism analysis in high-salt wastewater

Precipitation dechlorination has the advantage of being a simple process with a low cost. However, there are few reports on the effect of cations on dechlorination. In this study, we investigated the effect of cations in high-salt wastewater on the removal of chlorine ions by cuprous chloride precipitation and analysed the corresponding mechanism. A series of investigations revealed that Fe3+ could oxidise sulphite, thereby reducing the removal rate of chlorine ions. The reaction between magnesium and sulphite results in precipitation, which has a slightly adverse effect on the removal of chloride ions. Hexavalent chromium oxidises the chloride ion, resulting in the formation of chlorine gas, which improves the removal rate. Ferrous and manganese, however, do not have a notable effect on chlorine removal.

Chlorine Removal from U.S. Solid Waste Blends through Torrefaction

The amount of solid waste generated annually is increasing around the world. Although the waste has a high calorific value, one major obstacle that may prevent it from becoming a feedstock for power applications is the existence of polyvinyl chloride (PVC), which causes corrosion and emission issues after combustion due to its high chlorine content. Torrefaction is known to release hydrochloric acid; thus, it has been applied in this study for the reduction of chlorine from potential waste feedstocks. Fiber-plastic (60–40%) waste blends, with different chlorine content levels, as well as PVC were used in the current study. Torrefaction was conducted at 400 °C. Chlorine and heat content were measured. Experimental results showed that organically bonded chlorine was reduced during torrefaction as a function of mass loss. The chlorine removal efficiency was only dependent on temperature and residence time, not chlorine level. The heat content of the sample increased with mass loss up to a maximum of ~34 MJ/kg at ~45% mass loss. It was also observed that at ~30% mass loss, the organic chlorine content per unit heat content reduced by ~90%, while the heat content was ~32 MJ/kg, and ~90% energy was retained.