Magnesium oxide and magnesium hydroxide can both be used in various ways for the treatment of wastewater:
- In order to repel the unpleasant odor from waste water its main sources H2S and ammonia must be eliminated. This can be achieved by the introduction of MgO in the system with a buffer solution of 9-9,5 pH prohibiting in this way the formation of H2S.
- Corrosion of the utilities networks or sewage tanks is also attributed to the formation of sulfuric acid (H2SO4 ) alkaline magnesium reagents can help in their protection either with continuous addition magnesium oxide/hydroxide in parts of the network for pH adjustment or through coating the free surface of the pipes with magnesium hydroxide slurry.
- The removal of phosphorus is of major interest lately since phosphates interfere with the phenomenon of eutrophism and lead to the death of aquatic life. Additionally, due to the decrease of natural phosphate deposits the recovery and recycling of phosphorous has become desirable.
The byproduct of the phosphorus removal is called struvite and could be used as a fertilizer (Mg, N, P source). Magnesium ions provoke the increase of the chlorophyll production since they occupy the central position in its molecule, while N and P are important nutrients for the plants. In that way the treatments byproduct can be sold as fertilizer making the whole treatment process even more profitable.
It should be noted that the use of MgO / Mg(OH)2 achieves the best possible recovery yield of the phosphates in comparison to Ca(OH)2/CaO due to more effective pH control.