Effluent from the textile finishing industry is generally highly coloured and of a complex and variable nature. Conventional biological waste water treatment works are not designed to treat this type of ef-fluent with the result that colour and chemicals are not sufficiently removed and enter the receiving water bodies. This gives rise to public complaints, either due to aesthetic reasons or because it pre-cludes some down-stream use of the water.
The South African textile industry is the sixth largest employer in the manufacturing sector, with 80 000 people employed directly, an additional 200 000 indirectly in dependent industries and supports 80 000 cotton workers. It has local annual sales of R 7.7-billion and is the eleventh largest exported of manufactured goods. In addition, it is the second largest user of electricity from Eskom and the second largest rate payer of rates and taxes in towns and cities across South Africa.
The South African textile industry has been in a state of decline over the last 13 years and with the lowering of textile tariff rates, the industry is going to become increasingly exposed to international competition over the coming years. Therefore, in order for the textile industry to survive it must be-come more export orientated and economically competitive. However, with the introduction of eco-labelling, it will become increasingly difficult to export to the European Union and the United States of America unless textiles are manufactured according to this environmental legislation.
This project has focused on the Pinetown and Hammarsdale regions due to the number of textile mills in these areas discharging to the local wastewater treatment works. In both areas, the final efflu-ent from the treatment works were not complying with the standards set by the Department of Water Affairs and Forestry (DWAF), especially with regard to colour. Previous research projects involving the textile industry had focused on the in-house recycling of water and chemicals, with the concen-trates being discharged to sewer. Due to the increasing environmental pressure, both locally and world-wide, the South African textile industries must work towards reducing their environmental im-pacts by improving their processes and choice of chemicals and by addressing the problem of treating the concentrates.
This project was initially to have been undertaken by Umgeni Water, but was taken over by the Pollu-tion Research Group.
Project Aims
The main aims of the project were to :
- determine the fate of textile and specific industrial effluents through treatment processes;
- determine the effect of specific textile and industrial effluents on sewage treatment processes and on the quality of the final effluent;
- investigate the addition of polymers, flocculants or adsorbents at a sewage works to improve the removal of specific classes of pollutants;
- investigate the addition of processes within a sewage works to improve the removal of specific pollutants;
- investigate the treatment of specific concentrates which could be segregated at source;
- investigate the use of anaerobic digestion for the treatment of dye concentrates;
- initiate an effluent monitoring and targeting programme at selected sites in order to minimise waste, reduce effluent load, predict the nature of the effluent and to target problematic streams.