Generally in India and in other developed countries, the TDS aspect in the treated effluent is managed by mixing
the treated tannery effluent with domestic sewage, or, by discharging it into backwaters/Sea, wherever feasible.
The reduction in sludge volume and volatile solids concentration in the sludge as per the directions of
environmental regulations are managed by upgrading the CETP with total biological treatment with no or
minimum dosing of essential chemicals.
The universal options of two stage biological treatment with total detention times of 5-6 days, reduction in chemical usage by about 60 – 70% are being adopted in most of the CETPs in Europe including in the biggest CETP in Italy. This improves the DO level in the aeration system, better reduction in BOD, COD and reduces the sludge generation by more than 50% (i.e reduction from 7500kg to 3500kg). The volatile organic component in the dewatered sludge would be within the permissible limit in addition to the reduction in operation and maintenance cost towards the dewatering and disposal of sludge in the Secured Land Fill (SLF).
Mixing the treated tannery effluent with treated domestic sewage for TDS management, discharge the treated effluent to the backwaters / sea are some of the viable options and adopted in many leather sector CETPs in India and other countries including in Kolkata Leather Complex. Currently, the option of mixing the treated effluent with domestic sewage and disposal into Buckingham Canal leading to Sea has been approved by Pollution Control authorities for PTIETC CETP.
The implementation of the upgradation and TDS management project at a total project outlay of Rs.45.80 crores is being implemented by Pallavaram Tanners Industrial Effluent Treatment Co Ltd. (PTIETC) by forming a Special Purpose Vehicle (SPV). The direction and guidelines of DIPP sub-scheme of IFLADP, Tamilnadu Pollution Control Board (TNPCB) , Project monitoring Consultant CSIR-CLRI and other Agencies / local bodies are being followed by SPV.