Secondary waste water treatment is majorly aimed at removing dissolved but biodegradable organic matter from water after physically suspended materials are removed by the primary process(Bengtson, 2010, p. 2).
Majorly, these types of treatment use biological treatment processes to treat water but final consumption is done after tertiary treatment has been done.
Tertiary treatment is sometimes referred to as the advanced treatment because it treats what the primary and secondary methods have been unable to treat. Many of these types of treatment (tertiary) utilize chemical compounds to treat water (Bengtson, 2010, p. 1).
Both the secondary and tertiary treatment methods utilize a number of processes to make each step a success but tertiary treatment is never usually a necessity because it depends on the toxicity of the source of water.
Some of the most significant differences in these treatment methods are that the secondary treatment methods majorly utilize physical processes but tertiary treatment methods utilize chemical methods of treatment. Also, the tertiary treatment method is majorly undertaken with the aim of removing nitrate and phosphorous compounds from the water but the secondary treatment method is aimed at removing organic waste materials.
Lastly, the tertiary treatment method is not a mandatory procedure and varies from place to place but the secondary treatment method is mandatory and involves a couple of common processes such as the trickling filter, stabilization pond treatment systems and activated sludge (Bengtson, 2010, p. 4).
Appropriate Uses of Reclaimed Water
Reclaimed water can be obtained from many sources but it bears the qualities of being odorless, clear and high quality water, which enables it to be used for a number of purposes.
However, the most appropriate source for reclaimed water is irrigation but it is quite unfortunate that up to 50% of high quality water, which could be used for drinking, is used for irrigation (National Academy of Sciences, 2010, p. 3).
Reclaimed water can therefore act as a good substitute. However, reclaimed water can be used in a number of industrial irrigation processes and in supplementing natural system needs.
In this context, reclaimed water can be appropriately used in street cleaning operations; power generation plants; decorating fountains, quelling fires, dust control, aquifer discharge; cooling in industrial processes; and restoring depleted, natural systems (National Academy of Sciences, 2010, p. 3).
However, some people have got the whole concept of using reclaimed water for body contact wrong because it is inappropriate to use reclaimed water for recreational purposes (like swimming pool); cooking or drinking; or irrigating vegetable and other foods such as herb gardens – because they can directly absorb the contaminated chemicals from the reclaimed water and store them in their tissues.
Recommendation
Tertiary treatment methods are not good for ground water recharge and instead secondary treatment is recommended for this purpose. This is true because the operational plant facilities are likely to be affected by tertiary treatment methods because they eliminate nitrates and phosphates which are essential for ground water recharge, especially when the recharge is expected to support portable use, including metallic toxicants, or when the recharge process is expected to use nitrogen compounds and pathogens.
However, tertiary treatment methods are useful for treating drinking water because many drinking water purification plants use the process to clean raw water. Moreover, the process can be used to remove impurities which the primary and secondary processes are unable to.
References
Bengtson, H. (2010). An Introduction to Primary, Secondary, and Advanced Wastewater Treatment Methods. Retrieved from https://www.brighthub.com/environment/science-environmental/articles/68537.aspx
National Academy of Sciences. (2010). Source Waters and Their Treatment. Retrieved from https://www.nap.edu/read/4780/chapter/4