The article mainly targets the pollution caused by the dye effluents which are discharged into the nearby land by cottage dyeing and bleaching units without any proper treatment. The effluents from these units contain synthetic dyes and salts which affect the soil quality and contaminate the underground water.
Many cottage units are found across the districts of Tamil Nadu like Coimbatore, Tirupur, Salem, Theni, Dindigul, Madurai, etc. Also, there is a cluster of units present in the location which will lead to the mass contamination of underground water. The unit is located on the outskirts of the city due to the restrictions of the Pollution Control Board. Transporting the finished products becomes a challenge for them.
The problem of contamination of soil and underground water could be limited by implementing an ETP in this cottage dyeing unit. The ETP should be capable of removing the dyes and salts to the maximum percentage present in the effluent. This will also solve their transportation problem by shifting their unit near the market.
Solution proposed: The proposed solution consists of two steps. The first one is pretreatment with herbs and the second one with activated carbon
Activated carbon preparation and herbal powder preparation
After acquiring the coconut shell, it is processed to make the activated carbon. The coconut shells are heated at the required temperature in a closed furnace to convert them into carbon. Then it is activated by adding the chemicals like Zinc chloride, calcium chloride, etc.., The salts are mixed in water in the proportion of 3:1 and then the carbon is added to water and to settle for 22 to 24 hours.
Neem leaves, Vetiver root, Tulsi leaves and Lemon peel were collected washed with formaldehyde wash and acid-alkaline wash to remove dust and other impurities. Then plant materials were washed with distilled water. Finally, the washed herbs were dried and prepared in powder form.
Pre-treatment with herbs
The wastewater in a storage tank is sent to the pre-treatment process tank and the herbal powder is added to it. The proportion will be calculated based on the outlet water condition from the lab which will be analyzed after the reopening. The mixture is stirred with a mechanical stirrer for 20 mins and then it is allowed to stand without any disturbance for 2 hours.
Treatment with activated carbon
The output from the pre-treatment tank is sent to the final treatment tank where the water is treated with activated carbon. The activated carbon absorbs all the impurities in the water and leaves the water pollution-free.
Testing the recycled water
The recycled water is tested to ensure the parameters like Ph, COD, TDS are at the correct level. Once the testing is over the water is allowed to recharge the ground. These values are compared to water quality standards. If it is well coinciding with the standard values then the water is let into the ground otherwise it will be sent for retreatment.
Conclusion: The proposed solutions were based on the literature review. The results were under testing.
