Why the CETPs are ineffective
The infrastructure established in Gujarat for the treatment of industrial effluents and its effectiveness in treating pollution have been discussed in Chapters 8 and Chapter 10 based on empirical evidence. The common effluent treatment plants (CETPs), in spite of being operational for almost 20 years, have been found to be ineffective in treating the industrial effluents and have been unable to meet the prescribed standards. The values of treated effluents from the CETPs are much higher than the prescribed standards. The release of partially treated industrial effluents have completely degraded the quality of receiving water bodies. In India, the major composition of the industries, to the tune of 90 per cent, falls in the micro, small and medium enterprises (MSMEs) category and for these, there is no other option but to have common infrastructure to treat the water pollution generated from industrial processes. The same has been emphasised time and again by various policies and judicial orders. To have a deeper understanding of the factors which affect the effectiveness of CETPs and to qualitatively assess the reasons for the ineffectiveness of the CETPs, discussions were held with the representatives of the regulator, academicians, institutes, non-government organisations (NGOs) and the CETP operators. This is presented in the following paragraphs.
Different effluents, same treatment in the CETPs
The CETPs are different from each other in terms of capacity, composition of member units (homogenous or heterogeneous) and the concentration of inlet effluents. However, the treatment employed by all the CETPs is the same: a primary treatment followed by a secondary treatment based on biological processes, irrespective of the characteristics of the wastewater. The design of the CETPs has been adapted from the design of the sewage treatment plants (STPs) and it is incapable of treating a complex industrial mix1. The concentration of pollution in industrial effluents is much higher in Ahmedabad compared to that in Surat. In fact, in many cases, the inlet concentration of effluents in the CETPs in Surat is less than that of the treated effluents in Ahmedabad. Still, the treatment employed in the CETPs in Ahmedabad and Surat is the same. The consent orders issued to the CETPs under the Water Act do not specify the abatement technology to be used. The CETP operator is allowed to choose the abatement method for treating water pollution and meet the prescribed standards. This raises a big concern about the effectiveness of the treatment systems employed by the CETPs to reduce the pollution load and meet the prescribed standards.
Different inlet but same outlet norms for the CETPs
Inlet norms for all the CETPs are not prescribed and even the CETPs for which inlet norms have been prescribed vary from 300 mg/1 to 1500 mg/1 of the biochemical oxygen demand (BOD), but the outlet norm for all the CETPS is the same at 30 mg/1. The CETPs in Ahmedabad have made it compulsory for member units to do a pre-treatment of industrial effluents to meet the CETP inlet norms, whereas the CETPs in Surat have not made this mandatory for their member units2. This concept of different inlet norms, same treatment and same outlet norms is quite puzzling. When all the CETPs use the same kind of treatment, they would have similar pollution reduction efficiencies, and, technically speaking, the pollution levels in treated effluents would be directly linked to the pollution levels in the inlet effluents. Under such circumstances, how can the same discharge standards be prescribed, when the concentration of the inlet effluents is different? This leads us to believe that the standards are prescribed to the CETPs without considering the treatment efficiencies.
In practice, large variations have been observed in the inlet pollution load of the CETPs. For instance, in the case of CETP GVMM (Gujarat Vepari Maha Mandal) in Ahmedabad (Chapter 8), the values of the BOD in the inlet effluents varies from 70 mg/1 to 1650 mg/1. The bacteria are very sensitive to large fluctuations which can destabilise the treatment system and may even kill them. This type of large variation in pollution load will never allow the biological treatment systems to stabilise and perform at their optimum efficiency. This is quite evident from the average pollution reduction efficiency of this CETP which is mere 44 per cent as against an expected 85 per cent. The large fluctuations in the inlet load could be one of the reasons why none of the CETPs are able to meet the outlet norms.
