Study on quality of effluent discharge by the Tiruppur textile dyeing units and its impact on river Noyyal, Tamil Nadu (India).
In Tiruppur, 729 textile dyeing units are under operation and these units generate 96.1 MLD of wastewater. The untreated effluent was discharged into the Noyyal River till 1997. After the issuance of directions by Tamil Nadu Pollution Control Board (TNPCB) in 1997, these units have installed 8 common effluent treatment plants (CETP) consisting of physical, chemical and biological treatment units. Some of the units have installed individual ETP (IETP). The treated effluent was finally discharged into the river. The dyeing units use sodium chloride in the dyeing process for efficient fixing of dye in the fabric efficiently. This contributes high total dissolved solids (TDS) and chlorides in the effluent. CETPs and IETPs failed to meet discharge standards of TDS and chlorides and thereby significantly affected the river water quality. TDS level in the river water was in the range of 900 - 6600 mg/L, and chloride was in the range of 230 - 2700 mg/L. Orathupalayam dam is located across Noyyal river at 32 km down stream of Tiruppur. The pollutants carried by the river were accumulated in the dam. TDS in the dam water was in the range of 4250 - 7900 mg/L and chloride was in the range of 1600 - 2700 mg/L. The dam sediments contain heavy metals of chromium, copper, zinc and lead. In 2006, the High Court has directed the dyeing units to install zero liquid discharge (ZLD) plant and to stop discharging of effluent into the river. Accordingly, the industries have installed and commissioned the ZLD plant consisting of RO plant and reject management system in 2010. The effluent after secondary treatment from the CETP is further treated in RO plant. The RO permeate is reused by the member units. The RO reject is concentrated in multiple effect evaporator (MEE)/ mechanical vacuum re-compressor (MVR). The concentrate is crystallized and centrifuged to recover salt. The salt recovered is reused. The liquid separated from the centrifuge is sent to solar evaporation pan. The salt collected in the solar pan is bagged and stored in secure land fill facility. Thus, the discharge into the river is now stopped. However, the damage caused to the groundwater and soil contamination in the river basin is yet to be restored.
Tamil Nadu Pollution Control Board, Chennai - 600 032. rk260467@gmail.com
A Samuel
AS
Rajkumar
S
S
Nagan
D057919:Biological Oxygen Demand Analysis; D002712:Chlorides / Q000032:analysis; D007194:India; D007220:Industrial Waste / Q000032:analysis*; D019216:Metals, Heavy / Q000032:analysis; D045483:Rivers / Q000737:chemistry; D013431:Sulfates / Q000032:analysis; D013783:Textile Industry; D014865:Waste Disposal, Fluid; D014873:Water Pollutants / Q000032:analysis*
D002712:Chlorides; D007220:Industrial Waste; D019216:Metals, Heavy; D013431:Sulfates; D014873:Water Pollutants