Combined Biological Treatment/Ozonation of Wastewaters for the Mineralisation of Non‐Biodegradable Naphthalene‐1,5‐Disulphonic Acid

Abstract

AbstractThis paper deals with the ozonation and biological treatment for achieving the mineralisation of the non‐biodegradable compound naphthalene‐1,5‐disulphonic acid (NADSA; C10H8O6S2), a basic chemical for dyes and building materials. This combination of ozonation and biological treatment is expected to minimise the ozone consumption compared to ozonation alone. To examine the influence of ozone on the biodegradability of NADSA, a lab‐scale plant was run semi‐continuously and batch tests were conducted for comparison. For total ozonation, 1.8 mol O3/mol DOC have to be used. For optimum biodegradation, only 0.8 mol O3/mol DOC are needed. The results show that by using a combination of ozonation and biological treatment the ozone consumption can be reduced by more than 50% compared to ozonation alone.Some of the intermediate products are isolated and suggestions for their chemical structures are made. A proposal for the first steps of ozonation is also presented to illustrate a possible pathway of ozonation. All the major identifiable compounds are non‐biodegradable. From these results, it is quite clear that further intermediate products are formed, which are biodegradable.