Water reuse – a viable alternative for industries

Water reuse is the use of wastewater for a beneficial purpose, such as agricultural irrigation or industrial cooling, and is practiced in many parts of the world; and a leader in this area is Singapore.

The Beetham Wastewater Treatment Plant discharges 20 mgd (million gallons per day) of highly treated effluent that meets and surpasses the EMA’s Water Pollution Rules 2001 for effluent quality. In fact, during the harsh dry season of 2010, Petrotrin was supplied with 1mgd of treated effluent to supplement its raw water supply. This became necessary after Petrotrin’s reserves at its impounding reservoir, at the Pointe a Pierre Refinery, had run low. The treated effluent was used for cooling purposes at the refinery.

Global water issues and needs will make water reuse one of the crucial components in water supply strategies and the New Frontier of water resources management. It is believed that it is essential for wastewater and water professionals to evaluate water reuse to a strategic level in their planning process so that this limited resource can be efficiently managed and properly preserved.

Reclaimed water, sometimes called recycled water, is (former) wastewater which has been treated to remove solids and certain impurities, and then used for servicing water demands in various areas. Water reuse and reclamation is a new paradigm in water resources management that incorporates the principles of sustainable development, environmental ethics and public participation in project development. Although the immediate drivers behind water reuse may differ in each case, the overall goal is to close the hydrological cycle on a much smaller, local scale. In this way, the used water after proper treatment becomes a valuable resource.

Rationale and benefits of water reclamation

and reuse include the following considerations:

* Water is a limited resource, increasingly there is no longer the luxury of using water only once

* The acknowledgement that water recycling is already happening and the continued need is apparent

* The quality of reclaimed water is appropriate for many non potable applications thus providing a supplemental water source which allows for more effective and efficient use of water

* Allows for more efficient use of energy and resources by tailoring treatment requirements to serve end users of the water

* Augment water sources to meet present and future demands

* Protection of aquatic ecosystems through reduction of contaminants entering waterways

* Reduction of the need for impounding reservoirs

* Assist with meeting environmental regulations by better managing wastewater discharges and water consumption.

In 2011, WASA and the Public Utilities Board of Singapore (PUB) signed a Memorandum of Understanding to which the parties agreed that a Singapore team would assess the state of WASA’s water and wastewater systems. The main objective was to identify priority areas and develop technical proposals for potential consultancies.

A PUB-CPG Consultant team now provides technical support and services and for the Beetham Wastewater Treatment Plant Reuse Project.

There was agreement on the following key

design considerations for the construction

of the Water Reuse Facility:

* Plant location

* Capacity of Water Reuse Plant and Pipeline

* Reuse water quality standard

*Treatment process/technology

The PUB-CPG team submitted a Draft Technical Report - Technical Study and Concept Design. The report highlighted:

* Beetham Wastewater Treatment Plant

* Wastewater influent Flow

* Effluent Characteristics

* Key considerations of Concept Design

* Conceptual Design of Treatment Process

* Site Layout

* Transmission and Storage

* Cost and Implementation

* Recommendations to Enhance Water Security

A WASA Technical Team conducted a review of the draft and the final report is now under consideration.

As a further initiative, WASA is currently finalising a Memorandum of Understanding with the National Gas Company of Trinidad and Tobago to collaborate in the implementation of its water reuse strategy.

(Courtesy the Water And Sewerage Authority)