Preliminary And Primary Treatment Process In Wastewater

Steven FraserYanique Watson

Wastewater Treatment Processes

Approximately 93% of Jamaica’s municipal wastewater is handled by the NWC

Municipal Wastewater consists of: Black water

Grey water

Storm water

Infiltration

There are approximately 68 NWC Wastewater Treatment Plants with varying methods and equipment

Treated Effluent The discharge from Wastewater Treatment Plants must meet the

standards for treated effluent as set out by NEPA

Preliminary and Primary Treatment

Both have to do with the physical aspect of the treatment processPreliminary consists of removal of large particles

Primary removes the smaller particles by settling and skimming of the top of the wastewater

Preliminary Treatment

Screening

Bar Rack Bar Screen

Comminutor

Grit Chamber Comminutor

Flow Equalization

Is used for storage

To prevent short circuit

Control the waste water

Primary Treatment

Circular Clarifier

Rectangular Clarifier

Effective Primary Treatment

Primary Treatment removes:50-70% of suspended solids25-50% of organic content25-30% of BOD5

65% of oil and grease10% insoluble phosphorousSome organic nitrogen, phosphates, heavy

metals

Primary Effluent

Primary effluent still contains:Colloidal and dissolved solidsHigh levels of organic material NutrientsPathogens

Primary effluent is disinfected with chlorine to reduce pathogen load

References

Baker, S. (2015). Wastewater Management Systems. Lecture, University

of Technology, Jamaica

Ministry of Health - Environmental Health Unit. (2007). Minimum

requirements for wastewater treatment systems and excreta

management in Jamaica. Kingston: Ministry of Health.

Office of Utilities Regulation. (2011). water and sewerage sector report.

Kingston: Office of Utilities Regulation.

Wastewater treatment. (2015, August 18). Retrieved from National

Water Commission: http://www.nwcjamaica.com/WASTE_WATER.asp