Pollution Control Status of Secondary Lead Smelters

Many secondary lead smelting units are operating in the country to recover and re-use lead from waste scrap. However, the process of secondary lead smelting itself generates lead bearing solid waste from which further lead recovery is not economical. It also generates lead-bearing emissions. Kolkata is one of the oldest and major manufacturing centres of unorganised automobile battery. Lead from lead plates in battery manufacturing units was sourced mainly from secondary lead smelting units located in various clusters in and around Kolkata. The study was aimed to ascertain the present pollution potential of these units. The major findings of the study are:

Ø      All the units have installed adequate emission control facilities;

Ø      The pollution control equipments are also economical, as further recovery of lead is possible from the dust arrested in these equipments; and,

Ø      Most of the units are able to meet the standards as prescribed by the West Bengal Pollution Control Board.

Non-recyclable slag is the solid waste from secondary lead smelters. This waste is hazardous in nature and poses major problem due to non-availability of safe and notified hazardous waste disposal site. Presently, all the industries are collecting these wastes in a secure dump yard within their premises, from where the possibility of mishandling and disposing of solid waste to low lying area is very high.

Performance Study of Coke Oven By-product Plant

In an integrated steel industry, wastewater generated from Coke Oven By-product Plant (COBP) is a major polluting stream containing toxic chemicals like phenol, cyanide and ammonia. In recent times, COBP effluent is treated by biochemical oxidation of cyanide, ammonia and phenol at separate effluent treatment plants, commonly known as bio-chemical oxidation & dephenolisation plants (BOD plants). The treated effluent from BOD plant is recycled for use in quenching hot coke in coke-ovens. However, excess treated water has to be discharged into common outlet drain of steel plant. Almost all the integrated iron and steel units have installed BOD plants. Wastewater reduction in COBP involves reduction of pollution load in process wastewater and proper operation of BOD plant. Detailed study was conducted to evaluate the performance of BOD plants based on proper design, inlet concentration, type of treatment units, operation and maintenance and trained manpower.

Pollution control in Coal Based Thermal Power Plants

There are 81 coal based thermal power plants comprising total installed capacity of 60263.5 MW. Thermal Power plants are mainly responsible for air and water pollution besides problems related to solid waste (flyash) management. Out of 81 thermal power plants in the country, 42 plants comply with emission standards, 3 plants are closed and remaining 36 plants are in the process of installation/augmentation of pollution control systems. As regards water pollution prevention measures, 49 plants comply with ash pond effluent standards, 3 plants are closed and 36 plants are in the process of installation/augmentation of ash ponds. The main factors affecting the performance of Electrostatic Precipitators are:

·        Low design efficiency of pollution control equipments installed in various thermal power plants;

·        Inefficient operation;

·        High ash content in supplied coal; and,

·        High resistivity of fly ash

Constitution of National Task Force

A National Task Force has been constituted to assess the progress made in the implementation of the environmental standards and Rules, use of beneficiated coal and utilization of fly ash.

Use of Beneficiated Coal

Presently, beneficiated/blended coal is being supplied to Dadri (U.P.), and Badarpur (Delhi) Power Plants of National Thermal Power Corporation (NTPC), Dahanu (Maharashtra), of Bombay Suburban Electricity Supply ( BSES) and Rajghat & Indraprastha (Delhi ) Power Plants of Delhi Vidyut Board (DVB). However, other 26 plants have not yet indicated their plan for meeting the requirement of use of beneficiated coal. The implementation of provisions made under the above gazette notifications would be helpful in mitigating the problems of air pollution and management and handling of flyash disposal in environmentally acceptable manner in thermal power plants. 

Utilization of flyash

Sixteen percent of total flyash generation (80 million tonnes) in the country is utilised mainly for manufacturing cement, bricks and construction of roads and embankments. However, in advanced countries like Germany, China, USA, European Union and Japan, the extent of utilisation of flyash is 100%, 42%, 65%, 80% and 85 % respectively.

The State Pollution Control Boards were required to identify the brick kilns located within 50 km radius of power plants and modify the consent conditions as per the directives. Though, Orissa and Gujarat  Pollution Control Boards have identified the brick kilns but the status of flyash utilisation by these kilns is not yet available. Out of 81 thermal power plants, 46 power plants have submitted their action plan to achieve hundred percent flyash utilization within the stipulated time period.

Review of stack height regulations

A study on stack height regulation : "A state of art review through computer simulations and development of spacially meaningful regulations" was conducted by IIT Kanpur under a project sponsored by CPCB. The report includes basis for revision of stack height regulations, methodology for determination of minimum stack height and proposed stack height regulations for different zones of the country. The new stack height regulations will be finalized by a Working Group constituted by CPCB.

Assessment of requirement of Bag filter vis-a-vis ESP in Thermal Power Plants

A study has been undertaken with the following objectives:

·                    Evaluation of performance of ESPs in selected units of different capacities;

·                    Identification of reasons for poor performance of ESPs;

·                    Assessment of techno-economic feasiblity for installation of bag filter;

·                    Cost benefit analysis of ESPs vs. Bag filter in different unit sizes to comply with environmental standards for following scenarios;

·                    Retrofitting of Existing ESPs; 

·                    Bag filter as a replacement of existing ESPs; and,

·                    Techno-economic feasibility for the installation of bag filters in new thermal power plants.

Alternate flysah disposal technologies

Through IIT Delhi, a project has been taken up to study the following:

Ø      Evaluation of existing conventional practices of coal ash disposal based on dilute slurry disposal taking into consideration the water and energy requirements per tonne of flyash disposal. Since the distance of the ash pond from the plant would vary from one location to another, typical cases would in terms of conveying distance would be considered. This would also include the cost of the installation of the systems;

Ø      Evaluation of alternative ash disposal systems such as: disposal of ash in dry form as mound and disposal of ash into the ash pond in the form of high concentration slurry;

Ø      Comparison of dilute slurry system with alternate ash disposal system. This would include the cost factors relevant in each case and any other facts that need to be considered;

Ø      Cost related to operation, maintenance and environmental aspects of ash ponds/ash mounds for various disposal systems; and,

Ø      Combination of slurry disposal alternatives.

CETP for Sago Industries

Sago industries in Tamilnadu (around 1000 units) are based on tapioca roots and mostly under small scale industries (SSI) sector. The treatment plants set up by individual units are not being properly operated. It is therefore proposed to set up a CETP for the sago industries located along Thirumanimuttar river. The wastewater from sago industries located along Thirumanimuttar riverbanks will be collected and treated at the CETP. Tamil Nadu Pollution Control Board has been requested to carry out the inventory of starch and sago industries in Salem town.

Common Chrome Recovery Plant

In Jajmau area of Kanpur, more than 300 tanneries of varying capacity are in operation. Many of the large and medium tanneries have installed the chromium recovery plant at the individual level. For small tanneries, CPCB has taken up a project to recommend cost-effective possibilities for installation of common chrome recovery plant.

Inventory and Pollution Control Measures in Lime Kiln Units

In order to prepare an inventory of lime kiln units, all the SPCBs/Uts were requested to provide the updated list of lime kiln units operating in their States/UTs as well as the information regarding implementation of pollution control measures taken up by these units. The information is required to finalise inventory of lime kiln units being operated all over the country and to assess the magnitude of pollution load generated from these units.

Pollution Control In Small Scale Industries

The small scale industries (SSI) covering a wide spectrum of industries in small, tiny and cottage sector account for 40% of total industrial production in the country, 35% of total exports, manufactures more than 7,500 products and employ about 16.7 million person. However, unplanned, uncontrolled and haphazard growth of these industries have resulted in aggravating pollution problems. CPCB has undertaken an exercise to estimate the pollution load from industrial sources and to assess the status of pollution control in various sectors of small scale industries.

Human Risk Assessment in Asbestos Industries

Asbestos is a proven carcinogen and its exposure is associated with the development of lung cancer and mesothelioma. CPCB initiated human risk assessment studies in asbestos industries in collaboration with the Industrial Toxicology Research Centre, Lucknow. The study includes environmental monitoring of asbestos based industries, detailed medical examinations of industrial

workers, geno-toxicological evaluation of asbestos exposed population and recommendations for preventive measures in industrial units. The study at two asbestos plants has been completed.

Oil Drilling Units

Preliminary survey and inventorization of the oil-drilling units has been carried out in Upper Assam. The oilfields of Upper Assam, owned by Oil India Limited and Oil & Natural Gas Commission Limited, were visited to study the pollution aspects and also groundwater quality monitoring was conducted in the surroundings of injection wells.