By: Dr L M K Tillekeratne
Former Director, Rubber Research Institute
This was one of the hottest topics discussed everywhere in Sri Lanka recently after the unfortunate incident that occurred there a couple of weeks ago. I have gone through most of the letters and articles which appeared in the media in this regard, and some of them have been written by people not fully aware of the production process of latex-based gloves for domestic and industrial use.
It is totally wrong to believe that acids are used throughout the process of glove manufacturing like in the case of sheet rubber (RSS) and Crepe rubber manufacture.
Latex-based gloves manufactured by Dipped Products Factory at Weliweriya, uses neutral calcium nitrate as the coagulant and not formic acid. Hence there is no acid going down the drain during manufacture of gloves. The only liquid effluent discharged by the factory during the process is effluent resulting from washing, leaching and from the chlorination operation done to minimize tackiness, and leached protein levels of gloves.
As the entire manufacturing operation is done in the basic media at pH around 8, there is no chance of any acidity adding into the soil from these liquid effluents, even if they are sent down drains untreated. As an additional precaution waste water is treated in an effluent treatment plant prior to discharging into the environment.
Occasionally, contaminated ceramic formers are washed with acids to remove sticky materials and stains. These acid washings are neutralized and made slightly basic at a pH level around 8, before sending into the oxidation treatment ditch, along with other washings. Most of the public may not be aware that the pH of the treatment ditch should remain close to neutral point (at pH 7); because in the acid media below pH 7, the bacteria converting effluents die making the system ineffective. After this initial treatment, the waste water is sand filtered before releasing to the environment.
However, if chromic acid is used for former washing strict instructions are issued by the RRI to treat chromium contaminated effluent in a different and more effective manner. However, I have come to know that the Dipped Products factory does not use chromic acid and instead uses other acids for this purpose.
When this factory was set up, the Rubber Research Institute was very happy as it was going to convert small holders’ latex, which was otherwise being used for low grades of RSS. It enabled more foreign exchange earnings for the country while making it possible for small holders to earn a fair farm gate price.
It must also be mentioned here that even among all rubber products produced in the country, value addition is highest in the case of gloves industry, where sometimes nearly 90% of the material in the end is pure natural rubber and less than 10% of imported chemicals are used.
But in the moulded hard rubber products industry including solid tyres, only less than 50% is rubber and the balance composed of imported chemicals. Hence, the value addition is far below that of gloves.
"It is my view that the factory at Weliweriya is not responsible for the ground water acidity. Authorities must take a decision with regard to this matter after carefully considering the views of reputed scientists, and should not be misled by miscellaneous testing centres with little or no understanding of factory operations"
Further, I am well aware that they set up the factory under the guidance of the RRI, taking adequate precautions to nullify ill effects to the environment from the whole process, in addition to the environmental licence obtained from the CEA.
As far as I know, this company has not diversified their end products or deviated from the production process, which I knew well during my service period till 2007. If so, how can they be blamed for polluting the ground water in the whole area with acid? Is there any scientific basis to these wild allegations? Like in most parts of the wet zone in the country, the soil in this district is acidic and the pH is around 5.5 and that is why the area is best for planting pineapple from the time of Portuguese rulers.
It should be also noted that the company in question has been a success story and has been able to earn over Rs. 9 billion during the period 2011 - 2013, while catering to nearly 4,000 small holders of the area and providing employment to hundreds of Sri Lankans.
Hence, authorities must take a careful decision with regard to this matter after carefully considering the views of reputed scientists of the country who are fully conversant with the industrial chemistry of gloves production and not be misled by miscellaneous testing centres with little or no understanding of factory operations. It is my view that the factory at Weliweriya is not responsible for the ground water acidity as the water discharged from the factory is not acidic but alkaline.