Industrial Chemistry > 6. The Solvay process has been in use since the 1860s > Environmental Issues Associated With The Solvay Process >
Discuss environmental issues associated with the Solvay process and explain how these issues are addressed
Solvay process has been used since the late 19th century when it began to replace the Leblanc process. However, this industrial process still results to some major environmental concerns such as:
- Disposal of calcium chloride
Calcium chloride is the main by- product of the Solvay process which is produced in vast amount. For some instances, this was sold to different industries where it can be used as a concrete additive, drying agent or to melt ice on the roads. However, a high supply of calcium chloride heavily outstrips the demand for it. As a result, this by-product is being disposed to nearby landfills or waterways. High level of dissolved salts in waterways results to significant impacts in the local ecosystems. It causes destruction of vegetation in the area due to high chloride ion concentration. To address these issues, some Solvay plants used a more expensive method such as evaporation to dryness of the waste and disposal in specially designed burial sites.
- Thermal pollution
Since the Solvay process is an exothermic reaction, excessive amount of heat is liberated and released into the atmosphere and waterways. This can cause thermal pollution where a significant rise in temperature of about 5-10ºC was observed. Extreme heat in waterways can cause destruction of fish eggs and even deaths of aquatic organisms such as frogs and crab. To reduce this problem, the Solvay plants add water from nearby lakes and rivers to cool the wastes. Expensive heat diffusers are also used.
Some of the raw materials for the Solvay process are calcium carbonate and purified brine. To obtain these materials, mining should be done. Mining could lead to pollution and destruction of natural habitats. To address this problem, alternative sources for these raw materials were explored (e.g. brine from the ocean).
- Ammonia loss
Ammonia can be reused and recycled in the Solvay process, however, there are still noticeable amount of ammonia released into the atmosphere. When inhaled, ammonia can cause respiratory problems such as asthma and bronchitis. To reduce this problem, good design and careful monitoring were implemented in a Solvay industry.
Production of dust is also a problem brought by the Solvay industry especially for the people near the Solvay plant. It can cause allergies and respiratory problems such as asthma and bronchitis. This is being addressed by improving truck loading facilities and upgrading dust suppression systems in the plant.