Technology

Water purification and Wastewater treatment techniques have developed throughout the years to become part of our daily life ...

Technology advancements range from conventional treatment such as clarification and filtration processes to highly developed treatment such as membrane separation techniques.

Types of treatment, techniques, and process principles to be utilized, are dependant on the following factors:

	Water or wastewater source
	Influent quality or its level of contamination
	Effluent quality objective, and
	Intended usage of treated effluent

In order to purify water or treat wastewater, it is generally necessary to combine a number of basic processes, which may be physical, chemical or biological in nature. There are two main categories under which the treatment processes are classified, Physico-chemical and Biological.

Typically, any water purification or wastewater treatment techniques consist of the Main Treatment process, preceded by a Pre-Treatment scheme and followed by a Post Treatment process. Water or wastewater effluents can be further treated in downstream Polishing Loops. Treatment schemes are largely dependant on the Applications encountered in different Industries. For example, for seawater conversion to produce potable water, first suspended solids and colloids have to be removed (pretreatment), followed by a purification step to remove dissolved inorganic or organic pollutants (main treatment), and finally, some characteristics of product water need to be adjusted (post treatment).

Technology Classification and major unit processes involved in water purification and wastewater treatment are summarized in table 1

Table 1
Technology Classification

	Water Purification		Wastewater Treatment
	Technology	Typical Unit Processes	Technology	Typical Unit Processes
Pre- Treatment	Suspended Solids Removal	Clarification	Suspended Solids Removal	Clarification
		Filtration		Filtration
	Liquid-Liquid Separation (Oil Removal)	Flotation	Liquid-Liquid Separation (Oil Removal)	Flotation
		Adsorption		Adsorption
	Chemical Treatment	Coagulation/Flocculation	Chemical Treatment	Coagulation/Flocculation
		Precipitation		Oxidation
		Neutralization	Organic Pollutants Removal (Fermentation)	Aerobic Treatment
		Oxidation & Reduction		Anaerobic Treatment
	Disinfection	Oxidation		Bacterial Oxidation-Reduction
Main Treatment	Dissolved Solids Removal (Desalination)	Membrane Separation	Color Removal	Adsorption
				Membrane Separation
Post- Treatment	Gas Removal	Degasification	Chemical Treatment	pH Adjustment
	Chemical Treatment	pH Adjustment	Disinfection	Oxidation
	Sterilization	Oxidation	Polishing (Recycling)	Membrane Separation
	Polishing (Ultrapure)	Demineralization

Physico-chemical Processes

Required for treatment of effluents that contain Non-Biodegradable pollutants. Such processes include Suspended Solids Removal, Oil-Water Separation, Chemical Treatment, Dissolved Solids Removal, Gas Removal, Disinfection and Sterilization.

Biological Processes

Required for treatment of effluents that contain Biodegradable pollutants. Such processes mainly cover removal of Organic Pollutants.

Pretreatment

This is the process of conditioning water or wastewater stream for a downstream Purification or Treatment process (Main Treatment). Pretreatment equipment include conventional treatment schemes such as Clarifiers, Softeners, Filters, Chemical Feed Systems and Disinfection Equipment.

Main Treatment

This is the main process for Water Purification or Wastewater Treatment. It Includes all equipment employing Membrane Separation Process for treatment of the preconditioned feed water influent. Main Treatment also includes equipment utilizing Biological Treatment for processing pretreated wastewater stream.

Post Treatment

This is the process of conditioning water or wastewater effluent from the Main Treatment process to obtain the final product water, ready for use; or produce post-treated Wastewater effluent ready for disposal or reuse. Post-treatment equipment for conditioning of product water include Decarbonators (Degasifiers), Chemical Feed Systems and Sterilization Equipment. Post Treatment equipment for conditioning of treated wastewater effluent include Micron Filters, Carbon Filters, and Disinfection Equipment.

Polishing

This is an extra treatment step of the post treated Water or Wastewater Stream, to obtain Polished High Purity water, or Wastewater effluent, ready for Reuse or Recycle. Polishing Loops for Water and Wastewater effluents include downstream Membrane Separation Systems, Deionizers and UV Sterilizers.