A detailed study by the CSIR-National Institute for Interdisciplinary Science and Technology (NIIST), Thiruvananthapuram, has found several deficiencies in the operation of biofilter units installed in nearly 20 bonemeal units, chicken waste rendering plants, and rubber processing units in the Edayar industrial area.
The study, which was commissioned by the Kerala State Pollution Control Board (PCB) in September 2022, revealed that odour and volatile organic compounds (VOCs) were getting released from the erring units during raw material processing and plant operation owing to the poor operational efficiency of the units. The team of scientists shortlisted 10 possible reasons for uncontrolled emission into the atmosphere.
They included inadequate storage facilities for raw materials, lack of proper ventilation and refrigeration system for raw material storage, inadequate closure of reactor vessels, use of crude odour emission control technology for process, improper design and specifications of odour emission control unit, improper operation and maintenance of existing biofilter units, improper ventilation ducting in processing area, and lack of awareness among company workers as well as industry owners on environmental and health impacts of odour and VOC emissions.
The study report that was submitted to the PCB in September 2023 said that foul odour might not cause direct damage to health. But toxic stimulants of odour may cause ill health or respiratory symptoms. Secondary effects, in some, may be nausea, insomnia, and discomfort. Very strong odour could result in nasal irritation and trigger symptoms in individuals with breathing problems or asthma, it said.
The study recommended that all vapour emitting sources need to be channelised through ducts to a common conduit, after advanced scrubbing with relevant or proper scrubbing unit or biofilter unit.
The report pointed out that environment regulatory agencies, including Central and State PCBs, had a great responsibility to ensure that people living close to the odour-causing units were not impacted adversely in view of the unchecked emissions. The scientists said there was a lack of legislative obligation and Indian standards on odour and VOC emission levels in ambient air. Hence, critical scientific review was required on the effectiveness of installed biofilters for odour removal from respective processing facilities, they added.
