Energy Efficient Wastewater Treatment is not only preferable but also
crucial considering the ever-increasing utility demands and costs. In addition,
treatment plants have to meet more and more stringent discharge limits to
protect the environment and public health. As a result, unit treatment
processes are becoming more complex and energy intensive. Previously energy
efficiency was not in the equation. But now with increasing population and
limited energy sources, there is no way to ignore it. Adapting energy efficient
technologies and energy efficiency best management practices is now becoming
essential and mandatory.
Improving energy efficiency in wastewater facilities, a range of environmental, economic, and other benefits can be achieved. They are as follows (source: us EPA):
Energy represents a substantial cost in wastewater treatment, as it is
required almost all stages in the treatment process. With pumps, motors, and
other equipment operating 24 hours a day, seven days a week, water and
wastewater facilities can be among the largest consumers of energy in a
community. Electricity use accounts for 25-40 percent of the operating budgets
for wastewater utilities (US EPA). The following diagram shows energy
requirements break down by an activated sludge wastewater treatment process:
Source: Water and Wastewater
Energy Best Practice Guidebook, Focus on Energy (2006)
To optimize energy savings at a wastewater treatment plant (WWTP), a comprehensive energy management program should be adopted, implemented and monitored.
The U.S. EPA (2013) recommended sevens steps for designing, implementing, and sustaining energy efficiency improvements in water and wastewater facilities. This is a Plan-Do-Check-Act management systems approach, which is a circular evolving process that focuses on continual improvement over time.
The highlights of them are as follows:
Step 1. Get Ready
Establish the facility’s energy policy and overall energy improvement goals, secure management and employee commitment.
Step 2. Assess Current Energy Baseline Status
Establish a baseline and benchmark facilities.
Perform an energy audit.
Identify activities and operations that consume the most energy or are inefficient .
Step 3. Establish an Energy Vision and Priorities for Improvement
Identify, evaluate, and prioritize potential energy improvement projects and activities.
Step 4. Identify Energy Objectives and Targets
Establish energy objectives and targets for priority improvement areas.
Define performance indicators.
Step 5. Implement Energy Improvement Programs and Build a Management System to Support Them.
Step 6. Monitor and Measure Results of the Energy Improvement Management Program.
Step 7. Maintain the Energy Improvement