Mohamed Adnan Sami
Tamil Nadu National Law University
Effluent Treatment Plants (ETPs) and Common Effluent Treatment Plants (CETPs) are commonly used in the leather tanning industry to treat wastewater before it is discharged into the environment. ETPs and CETPs are effective in removing pollutants such as organic matter, suspended solids, and heavy metals from the wastewater. The effectiveness of ETPs and CETPs in treating the effluents in leather tanning industries depends on various factors such as the type of tanning process, the quality of the raw materials used, and the efficiency of the treatment process.
Analysis of the process involved in Effluent treatment plant
Firstly, in the pre-treatment stage of effluents, the chrome which is segregated is removed in the sludge settled in the tanks of pre-treatment units established within the tanneries. Following this, Segregation of soak & pickle liquor and evaporation using a solar light pan is carried out. Combined effluent other than some chromotised liquor is treated in a treatment unit which is followed by removal and disposal of grits at the end. Following this, the effluent which is treated is disposed of properly and effectively so that the effluents which are treated don’t affect the public at large.
Drawbacks of Effluent Treatment Plant- CLRI and NEERI
Even when it is being mandated to be implemented in the leather industries, there are various drawbacks which the effluent treatment plant has attached to it. In the Practical sense, the Effluent Treatment Plant or Common Effluent Treatment Plant is costlier and it has resulted in the closure of many such Leather Tanning Industries in and around Tamil Nadu, where the total number of leather tanning industries has drastically reduced. Apart from the practical difficulty, technically there are various difficulties which are specified in the below-mentioned list,
“Absence of mechanisms to protect the dilution system which filtrates the effluents. Improper pumping system for raw effluent from the receiving sump and improper screening of the effluent which prevent huge solid-like particles from approaching the treatment system. Insufficient combination and aeration levels in the tanks, in order to ensure sufficient mixing and oxidation of sulphides. Absence of appropriate chemical dosing and an inefficient filtration system. Inadequate aeration in the oxidation pits which creates a need for an additional secondary clarifier with appropriate provision for re-circulation of activated sludge in the pre-aeration/oxidation ditches.”
Even when some of these defects existing in the Effluent Treatment Plant system have been rectified, the entire drawbacks of the ETP system are not rectified properly, which makes this system slightly ineffective.
Apart from this, AISHTMA has engaged CLRI and NEERI to study the effectiveness of the Common Effluent Treatment Plant or Effluent Treatment Plant which put forward various drawbacks which could be listed as follows, “Chrome-bearing wastewater was not properly segregated in tanneries. A self-actuating system is not present for the sump pump which is present in the ETP, which leads to huge Electrical expenses. Absence of flow measuring device at the inlet of the Common Effluent Treatment Plant. Installation of additional aerator in equalisation tank. Disintegration of baffle wall in equalisation tank. Common Effluent Treatment Plant is not operating for 24 hours a day, which reduces the efficiency of the ETP or CETP.”
Thus, it could be concluded that Effluent Treatment Plants or Common Effluent Treatment Plants which are mandated for the Leather Tanning Industries are not completely effective as it has various drawbacks as pointed out by Scientific experts and NEERI. Apart from this, the financial and electrical supply difficulties for installation of Effluent Treatment Plants or Common Effluent Treatment Plants are the major practical difficulties attached to Effluent Treatment Plant installation.
Analysis of an alternative to Effluent Treatment Plant
Apart from the Common Effluent Treatment Plants and Effluent Treatment Plants, still, other cost-effective water treatment plants such as the borehole latrine, dug well latrine, aqua privy and ventilated improved pit latrine (VIP), are also available which are not mandated for the Leather Tanning Industries. This Chapter will analyse two cost-effective alternatives to the Effluent Treatment Plants such as the Sulabh Effluent Treatment System and other such alternatives.
Firstly, analysing the Sulabh Effluent Treatment Plants which were developed by a Non-Governmental Organisation called Sulabh in order to overcome the practical difficulties involved in the Effluent Treatment Plants which have various mechanisms to treat the effluents released by the Leather Tanning Industries which are effective.
Mechanisms involved in the cost-effective alternative to the Effluent Treatment Plants:
Firstly, filtration of effluents with the help of activated charcoal is done which is followed by ultraviolet (UV) rays treatment to the filtered effluents. The filtration unit makes it colourless, odourless and free from organic particles and UV eliminates bacteria from the effluents, which would eventually reduce the COD and BOD of the effluents through the treatment process.
The practical difficulties and drawbacks associated with the Effluent Treatment process have been rectified by this technique to an extent by covering the following aspects:
Costs on collection of effluent and operation and maintenance of the system is completely low
No manual handling of effluent is required under this technique.”
This method would be effectively applicable to the small-scale leather tanning industries, which is even mandated by the environmental standards to set up the effluent treatment plants or the common effluent treatment plants.
The importance of having a cost-effective alternative to the currently existing Effluent Treatment Plants or the Common Effluent treatment plants could be understood by the closure of various Leather Tanning Industries in and around Sembattu, Trichy which was a leather tanning hub until the 1990s.
Thus it could be derived that the Pollution Control Boards along with the Legislations have not considered the applicability of different treatment systems to different scale tanning plants and have mandated ETPs or CETPs as a whole which affects the highly influential leather tanning sector.
It is further found that the small-scale tanning units are just using animal extracts for the tanning process which doesn’t require the amount of treatment ETPs or CETPs mandate to protect the Environment by treating effluents. Thus it could be derived that the Pollution Control Boards along with the Legislations have not considered the applicability of different treatment systems to different scale tanning plants and have mandated ETPs or CETPs as a whole which affects the highly influential leather tanning sector.
Suggestion to the PCB
Now based on these findings, it could be suggested that the Legislation along with the Pollution Control Board should propose or design an Effluent Treatment Plant or Common Effluent Treatment Plant to ensure the cost-effectiveness of the plant in order to balance the environmental and economic aspects just like the SETP which is analysed by this research paper. Apart from the designing of a new proposal, fixation or regulation of different treatment facilities with different technologies (cost-effective) would balance the environmental and economic aspects in an effective manner as the current mandate is not effective.
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