Common Effluent Treatment Plants Overview

Study Notes

CETPs are a solution for collecting, treating, and disposing of industrial and domestic wastewater from industrial estates
CETPs are designed for small-scale and medium-scale industries, which often have small volumes of wastewater but high pollution potential
These industries typically cannot afford individual wastewater treatment due to space and financial limitations
CETPs are designed based on wastewater quality, flow rate, treated effluent standards, land availability, labor, power, and willingness of industries to contribute to capital and operating expenses
CETPs can be modified into combined effluent treatment plants, collecting domestic sewage from surrounding areas and treating it with industrial wastewater
Benefits include dilution of toxic constituents and inorganic dissolved solids in the industrial wastewater
CETPs can help control pollution
CETPs allow industries to focus on reducing pollution at source, and lowering water/energy consumption

Ownership can be: a private sector (individual industries forming a cooperative company), public sector (State Industrial Development Corporations (SIDCs) providing infrastructure) or a joint public-private sector (SIDC and Industry Association forming a company)
Private sector ownership's advantages include industry commitment to pollution control and addressing short-term manpower and equipment issues, although conflicts may arise regarding wastewater quality and quantity
Public-sector ownership may face conflicts between compliance and enforcement
Joint ownership improves funding availability but can lead to delays in assigning responsibilities

Basic information: raw materials, products, treatment, wastewater quality, and quantity, waste minimization and reduced consumption are considered.
Collection and Conveyance: Underground drainage systems or tankers for transporting waste water
Pretreatment necessary, before conveyance to a CETP
Master plan and phase-wise improvement is necessary if there's uncertainty about quantity, quality and treated wastewater
Sludge disposal planning and management is done

Unit cost of treatment increases if wastewater flow is low.
Heterogeneous industries wastewater treatment is more expensive than homogeneous ones'
Topography plays an important role in wastewater cost
Detailed techno-economic study is crucial for conveyance costs
Recommendations from a study of 40 CETPs suggest a detailed techno-economic assessment for conveyance costs, as conveyance costs can account for a large part of capital costs

Pretreatment measures by individual industries should be optimized
Phase-wise development of CETPs should be considered, prioritizing meeting required standards
Upgrading capacity of CETPs should be planned to accommodate potential increase in flows, stricter treatment requirements and waste quality
In-plant pollution control efforts should be encouraged

Modular approach, adapting to changes in wastewater volume as the estate develops
Upgradability approach, accommodating increased flows, tighter standards and recovery of valuable materials.
Service center approach, providing facilities (workstation, library, equipment and conference halls) to participating industries

CETP at Sarigam, Gujarat
- Four zones are served
- Total daily flow of 14,200 m³/day
- Treated wastewater was planned for reuse or farmland irrigation.
Heterogeneous industry complex CETP
- Problems include wide variations in wastewater characteristics and necessary pretreatment solutions (acidic pH, high TDS) and segregation of high TDS effluents for effective biological treatment.
- Potential for domestic sewage dilution/inclusion.