CHAPTER 11 : Waterwaste Management

What is Wastewater ?

• Waste Water is any water that has been adversely affected in quality by anthropogenic influence.

• It comprises liquid waste discharged by domestic residences, commercial properties, industry, and/or agriculture and can encompass a wide range of potential contaminants and concentrations.

What is Sewage ?

• “sewage” means any liquid waste or wastewater discharge containing human, animal, domestic, or putrescible matter in suspension or solution, and includes liquids containing chemicals in solution either in the raw, treated or partially treated form.

Sewage Content.

• Organic matter
• Nutrients (Nitrogen, Phosphorus, Potassium)
• Inorganic matter (dissolved minerals)
• Toxic chemicals (heavy metal and pesticides)
• Pathogens

Individual Septic Tank

• Premises with a proper individual septic tank (Malaysian Standards - MS 1228 ) has 3 to 4 rectangular metal covers and is usually located outside the premises.
• It only provides partial sewage treatment that flows into it & needs to be desludged approximately once in two years.

(http://www.mitchellandmitchell.com/blog/septic_tanks_what_are_they_what_to_do_before_buying_a_home_with_one.aspx)

Why Treat Sewage ?

• Environmentally-safe fluid waste stream and a solid waste suitable for disposal or reuse (usually as farm fertilizer).
• Using advanced technology it is now possible to re-use sewage effluent for drinking water.

Sludge

• Residual, semi-solid material left from sewage treatment processes or settled suspension from conventional drinking water treatment.
• Untreated sludge is a significant environmental & public health hazard.
• However, treated stabilized sludge is inert, stable and safe to use.

(http://www.slideshare.net/shankarmujoo/sludge-drying-beds)

Effluent Discharge

• Must be accomplished without transmitting diseases, endangering aquatic organisms, impairing the soil, or causing unsightly or foul-smelling conditions.

• Effluent standards define what is allowed within the wastewaters discharged into the aquatic environment.

• 2 most important parameters are Biochemical Oxygen Demand (BOD) and Suspended Solids (SS).

• BOD - amount of oxygen that sewage consumes over a given time. High BOD means, sewage rapidly consume all the naturally-dissolved oxygen in streams, rivers and lakes, thus killing off all aquatic life.

• SS - undissolved material in sewage. High SS leads to sludge deposits in the waterways, thus causing significant environmental deterioration.

Health Effects

• Contaminate via inhalation, ingestion, or direct contact to human by chemical, microbiological and biological properties of the sewage or sludge.

• The Centers for Disease Control and Prevention (CDC) says sewage workers are not at more risk of Hepatitis A infection than other workers.

• Sewage contain bacteria, fungi, parasites, and viruses that can cause intestinal, lung, and other infections.

• Bacteria such E. coli, shigellosis, typhoid fever, salmonella, and cholera may cause diarrhoea, fever, cramps, and sometimes vomiting, headache, weakness, or loss of appetite.

Environmental Health

Nutrient enrichment: Sewage with high concentrations nutrients can be responsible for the formation of algal blooms which reduce light penetration through the water column, may produce toxins and can cause oxygen depletion when decomposition takes place.

Guideline and Legislation

• Environmental Quality (Sewage) Regulations 2009

• Environmental Quality (Industrial Effluent) Regulations 2009

REFERENCES

• http://www.mitchellandmitchell.com/blog/septic_tanks_what_are_they_what_to_do_before_buying_a_home_with_one.aspx

• http://www.slideshare.net/shankarmujoo/sludge-drying-beds

• Notes that had been given by our lecturer's Sir Mohd Jamalil Azam bin Mustafa