study of steel re-rolling mill for mitigation measures with special reference to water recycling

Research Article
*Nafees, M., Zahid, Z and Naz, R
DOI: 
xxx-xxxx-xxx
Subject: 
science
KeyWords: 
Disinfection, KMnO4, Coliform Bacteria, Threshold odor Number (TON), Water Recycling, EIA, National Environmental Quality Standards (NEQS)
Abstract: 

Steel Re-Rolling Mill (SRM) is a simple industry consists of heating and re-rolling of billet. A heating kiln is used for the maintenance of specific temperature (1000 to 1200 oC) to mould billets/ingots into various desired shapes. After getting the desired shape, heavy amount of water ranging from 32 to 39 m3 per day is used for cooling. This water is discarded on daily basis or after few weeks time. This huge amount of water creates pressure on ground water resources as well as contributing to pollution load. These aspects of steel re-rolling mill are not clearly defined in the Pakistan Environmental Impact Assessment/ Initial Environmental Examination (EIA/IEE) rules and regulations, 2000. To study the possibility of water re-cycling as mitigation measure in steel re-rolling mill was analyzed for one year. It was found that wastewater of re-rolling mill, used for cooling purpose, can be recycled after minor treatment. By the frequent re-use of the same water the possibility of biological contamination may occur. The water can be used for longer period of time after proper disinfection. To confirm its usage/re-use Potassium permanganate KMnO4 was used as disinfectant. KMnO4 treatment was given to the wastewater samples collected from storage tank with concentration of 3 mg/L, 5 mg/L and 10 mg/L. It was found that combination of 3-5 mg/L was more effective to keep the water odorless and free from coliform bacteria. After repeated use, it was suggested to discard/discharged wastewater of steel re-rolling mill only once in a year during high flow season (July-August). In this way the wastewater will be diluted to the extent that it may have no/or minimum negative impacts on the receiving the water body as well as saving the ground water resources. It is therefore, suggested required to start work on individual industry and develop specific EIA and monitoring guidelines