Abstract
One of the negative effects of the continuous development of civilization which is observed in recent decades is an increase in the number and variety of pollutants released into the environment. These substances have ecotoxic properties and pose a serious threat to humans and proper functioning of the ecosystem. Their presence in the environment forces the development of new pollution control techniques. One of the latest and very promising methods to destroy organic contaminants using the properties of water which exceeded the critical point is thermohydrolysis in supercritical water. The aim of this study was to investigate thermohydrolysis in supercritical water conditions and to check its suitability for removal of hardly biodegradable organic compounds present in wastewater. Tests for toxicity of these compounds to aquatic organisms such as sewage bacteria, crustaceans and guppy fish were also performed and the degree of their biological decomposition was determined. Biological studies were carried out on starting compounds and after the processes of thermohydrolysis. The research material included p-nitrotoluene sulfonic acid (PNTS), 4,4′-dinitrostilbene-2,2′-disulfonic acid (DNSDS) and 4,4′-diaminostilbene-2,2′-disulfonic acid (DASDS). The research leads to the conclusion that the reactions occurring during high-temperature thermohydrolysis of the three tested compounds are extremely complex. Results of biological studies indicate a significant decrease in toxicity and increase in the biodegradability of products obtained after the process of thermohydrolysis.
Highlights
Uncontrolled economic development proceeding for decades, in particular the intensification of industrial processes, contributed significantly to the pollution of natural environment
A promising method of destroying organic pollutants is the process of thermohydrolysis in supercritical water which comprises thermal decomposition or transformation of the starting compounds
A lower degree of TOC reduction in relation to the tested compounds can be explained by the fact that in the reaction mass due to the process of thermohydrolysis the compounds were transformed into simpler organic compounds whose structure includes carbon expressed as total organic carbon
Summary
Uncontrolled economic development proceeding for decades, in particular the intensification of industrial processes, contributed significantly to the pollution of natural environment. One of the industries that has had the greatest impact on the environment is chemical industry This is due to the synthesis of thousands of new chemical compounds, often very toxic to the environment. A promising method of destroying organic pollutants is the process of thermohydrolysis in supercritical water which comprises thermal decomposition or transformation of the starting compounds. High effectiveness of this method results from the thermodynamic properties of water which change very rapidly, often by several orders, near the critical point (critical temperature Tcr = 374°C and critical pressure Pcr = 22.1 MPa) [4–6]. At the same time the loss of polarity causes that compounds with an ionic structure practically do not dissolve in it any longer [7–11]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
