Nowadays, more wastewater is germinated by our industrial, residential, commercial activities. It contains a variety of substances such as organic matter, toxic materials, pathogenic microorganisms and nutrients. If wastewater is discharged without treatment, it may cause serious water pollution. Therefore, the sewage treatment plant helps to remove the toxins or industry effluent from the wastewater to protect the environment. Sewage treatment plants have two primary functions. They treat wastewater to a level that allows its re-introduction to surface or ground waters; and they treat the solids produced in this process to either be recycled or disposed properly.
How it works?
What is biosolid?
The sewage is separated into liquids and solids during the treatment. Biosolids are a product of those solids that has undergone a further treatment to reduce the harmful chemical matters or organic matter significantly.
In some parts of the world, Biosolids are used to improve and maintain productive soil and stimulate plant growth (just as agricultural fertilizer), what are the pros and cons?
Pros:
-disposal of the biosolids is very expensive; using the biosolids as fertilizers can reduce the costs
-biosolids are rich in phosphorus, nitrogen, organic matter which are essential plant nutrients
-using biosolids as fertilizer germinate less liquid waste
-create jobs
Cons:
-trace of chemical matter or toxic materials may linger in the biosolids
-using biosolids as fertilizers may be harmful to the environment and to people's health because we are bringing back those chemical matters to our environment
-biosolid may contain chemical substances which can affect the plant growth
Potential stakeholders in this issue could be farmers because biosolid is cheaper than agricultural fertilizers; government because they do not have to pay a lot of money to disposal the biosolids; and it can create more job opportunities for us. I think using biosolids as fertilizer still needs further studies, so that we can ensure biosolids don’t contain any substances that would be harmful to our environment and our health.
Refernce:
http://saferenvironment.wordpress.com/2008/11/07/sewage-treatment-%E2%80%93-for-recycling-of-waste-water-use-of-biosolids-and-to-generate-renewable-energy-for-cleaner-safer-and-greener-environment/
http://www.environmentalhealthnews.org/ehs/newscience/soy-plants-accumulate-drugs-antibacterials-from-biosolids
http://lancaster.unl.edu/enviro/biosolids/fertil.shtml
