logo

Fertilisers and pollution

New pollution norms after three decades will push the sector towards a stringent pollution control regime, write Vinay Trivedi and Sugandha Arora Sardana.

Fertilisers and pollution
The Indian fertiliser industry is set to implement new pollution norms notified by the Union Ministry of Environment, Forest and Climate Change in December 2017. So far the industry had emission norms only for urea and phosphatic fertiliser plants but the notification has specified emission norms for ammonia, ammonium nitrate and calcium ammonium nitrate, complex fertilisers and nitric acid plants for the first time in 29 years.
The industry emits major air pollutants such as particulate matter, gaseous NH3, oxides of nitrogen, sulphur, and carbon dioxide. Prilling towers, which manufacture urea prills or pellets, are a major source of urea dust particulates. Even the wastewater generated possess pollutants such as ammoniacal nitrogen, phosphates, heavy metals, and fluorides in varied amounts, which can pose serious health hazards if not treated. In fact, many fertliser plants have been issued closure notices in the past owing to non-compliance of emission and effluents standards, suggest reports. The new norms are, thus, a welcome move for the sector, which got its first set of norms in January 1988, two years after the Environment Protection Act, 1986 was enacted. Until December 2017, no improvements or amendments were made in the norms. Thanks to technological upgradations in the past decade, it was felt that the sector was ready for new norms, say officials from the Central Pollution Control Board.
New norms are likely to bring improvements
There are three categories of fertilisers manufactured in India - nitrogenous, phosphatic, and complex fertilisers (which includes nitrogen, phosphorous, and potassium nutrients in different ratios). Depending on the type of fertiliser and the plant, the pollutants generated vary and thus, the need for different pollution norms.
The new set of emission norms include limits for nitrogen oxides in ammonia and nitric acid plants, which were missing earlier. Norms have also been introduced for particulate matter, gaseous ammonia and total fluoride for Ammonium Nitrate, Calcium Ammonium Nitrate (AN/CAN) and complex fertliser (NPK) plants. Even effluent norms have been improved in the notification. The effluent norms since 1988 had different limits for plants commissioned before and after 1982 due to differences in design. However, the new norms are uniform irrespective of its age. Secondly, permissible limits for key pollutants such as Total Kjeldahl Nitrogen and Free Ammonical Nitrogen have been made stringent in straight nitrogenous plants, comprising of Urea/CAN & AN.
Norms are still relaxed for old urea plants
Broadly speaking, there are two kinds of plants, those commissioned before 1982 and those commissioned after. The emission norms for particulate matter from urea prilling towers continues to be 150 mg/Nm3 for older plants commissioned before 1982. On the other hand, the norms are 50mg/Nm3 for plants commissioned after 1982. Since almost 50 per cent of the plants in India were set up before 1982, it means that most of the urea plants will continue to run with relaxed norms even in the coming years.
An expert from the fertiliser sector who spoke to Down To Earth anonymously reasoned that "The main reason for relaxed norms is that in older urea plants it is very difficult to install advanced pollution control mechanism. The prilling towers are old with conventional design and their structure and layout don't support modifications. In addition, space constraint reduces the possibility of putting up new technologies for pollution control."
Permissible limits for particulate matter emissions were stringent in the draft
Even though the emission norms have been notified for AN, CAN and NPK fertiliser plants for the first time in almost 3 decades, the new notification allows for relaxed permissible limits for particulate matter emissions compared to a July 2015 draft notification. The limit was relaxed from 50 mg/Nm3 for all plants in the draft to 150 mg/Nm3 for existing plants and 100 mg/Nm3 for new plants in the final notification.
When asked why the stated norms were not made uniform and stringent, a Central Pollution Control Board official, who spoke to DTE on the condition of anonymity said, "There is a huge variability in the processes and products manufactured in AN, CAN and NPK fertiliser plants. Since their emission potentials are different, it is not possible to meet uniform and stringent norms."
Also, the new set of norms has scrapped the limits for heavy metals (vanadium, arsenic and Chromium). Chromium-based chemicals that were used earlier as algaecide in cooling water system of urea plant are not in use anymore. The notification prohibits the use of chromium as it is highly hazardous. Similarly, vanadium and arsenic which were being used earlier in carbon dioxide removal process in ammonia plant have also been phased out.
While the new norms are a welcome move, merely having norms is not enough. The need of the hour is its effective implementation by the industry and ensuring a strong compliance check system by the pollution control boards.
(The views expressed are strictly personal)

Vinay Trivedi and Sugandha Arora Sardana

Vinay Trivedi and Sugandha Arora Sardana

Our Contributor help bring you the latest article around you


Exclusive

View All

Latest News

View All
Share it
Top