Solvay France has utilised a pH solution from Mettler Toledo for effective effluent treatment at its Tavaux facility.
For a number of years Solvay Fluor - the strategic business unit for the group - has been developing products that are compatible with environmental concerns.
One of these products is Solkane 365mfc, produced at the Tavaux facility.
This is a fluorinated solution used in manufacturing thermal insulation foams or as a high-performance solvent (for optics, high-performance degreasing, high-precision cleaning and so on).
It is replacing harmful HCFC (hydrochlorofluorocarbons) in the manufacturing of thermal insulation foams, as Solkane 365mfc has no impact on the ozone layer.
Solkane 365mfc manufacturing wastes are treated and regulated by prefectural decree.
In order to comply with the standards applicable to industrial wastes, Solvay Fluor has implemented effective aqueous effluent treatment facilities.
The waste is routed to a treatment plant where volatile organic compounds are removed by steam stripping and precipitation of metallic salts, before the fluid is discharged.
Due to the effluent being strongly basic and hot (65C) and containing fouling organic compounds, the difficult part in the treatment process is pH regulation.
In order to allow effective elimination of the organic components and precipitation of salts, the pH must be adjusted to between 12.5 and 12.7.
The fluid first has to be brought to the correct pH before it enters the stripping column.
As the steam process alters pH, the value must again be adjusted to the correct value to enable precipitation of the metallic salts on the filters that follow.
The pH solution offered by Mettler Toledo included a combination of its products: Intrac777 retractable housing, Inpro4800 pH electrode, 2220X pH transmitter, and an Easyclean automatic cleaning system.
The Mettler Toledo pH/temperature electrode is designed for rugged and demanding applications in the chemical industry.
The electrode enables reliable measurements in oxidising environments, solvents, strong acids or bases, and resists high pressures and temperatures.
Additionally, the Easyclean automatic cleaning system is designed for easy integration in explosion-risk areas (Atex II 2G).
In this process pH is an essential parameter and measurement is critical before discharge of the effluent or there is the risk of violating the standards.
Despite the presence of metallic salts and 10 per cent nitric acid cleaning every 60 minutes, the Inpro4800 electrodes provide a service life of around four to six months.
