The effluent received from the member tanneries is subject to manual and mechanical rack screen and collected in a collection well. From the collection well the effluent is pumped to the rotary screen to remove the residual fine leather trimmings, shavings, colloidal and floating matter. From the rotary screen the effluent will be discharged into the upgraded Equalization-cum-Homogenization system. The homogenization with aeration is schedule through Jet Aspirators. The homogenized effluent is pumped for further treatment with minimum chemical usage. The primary clarification is carried out using two sets of clarifiers. The settled sludge from clarifiers is collected and further dewatered using mechanical chamber filter press.
The clarified effluent is discharged into aeration tanks with upgraded aeration system using Jet aspirators from diffused aeration for better oxygen transfer, improved DO level and overall performance. From the improved aeration system, the effluent is collected in two sets of secondary clarifiers. The bio-sludge from the secondary clarifier is re-circulated to the entry point of aeration system.
The treated effluent from the secondary clarifier is further taken for tertiary treatment units such as Reactive Clarifier, Dual Media Filters (DMF), Micro Filters & Ultra-Filtration (UF). After Ultra-filtration the treated water is taken for water recovery by adopting two stage Reverse Osmosis (RO) system. The Multiple Effect Evaporator (MEE) installed in PTIETC CETP is found not suitable for the effluent received from the member tanneries probably due to the discontinuation of raw to semi-finishing operations to reduce the overall pollutional load to the CETP. As a sustainable alternative option for TDS management it is scheduled to pump the treated effluent after advance oxidation treatment to Perungudi STP for dilution / mixing with treated domestic sewage and disposal by meeting all the discharge parameters.
The dilution/mixing proposal for sustainable TDS management has been approved by TNPCB and implemented by CMWSSB as a deposit work. The project is expected to be completed by the middle of 2022.