Water Environment & Technology (WE&T) is the premier magazine for the water quality field. WE&T provides information on what professionals demand: cutting-edge technologies, innovative solutions, operations and maintenance, regulatory and legislative impacts, and professional development.
Four MBRs are better than one
Eight years ago, Paulding County, Ga., home to 145,000 people and covering approximately 830 km2 (319 mi2), consistently ranked between the 12th and 15th fastest-growing counties in the United States. The county’s Pumpkinvine Creek Wastewater Treatment Plant, which had been using a sequencing batch reactor (SBR) and sand filter system, was operating close to design capacity. With tighter effluent limits on the way, a halt on surface water discharge permits, and an increase in required capacity, the county had to look at alternative uses for its treated wastewater. Reuse became the only viable option.
Maximize filtration effectiveness
Tertiary filters are a critical wastewater treatment process; they help capture solids escaping secondary clarifiers and maintain a great final effluent quality. Although many filter technologies can be used, slow sand filtration is still widely applied because of its reliable performance and low maintenance costs.
Researchers recently conducted a series of full-scale stress tests on a group of sand filters to determine which factors most affected filter capacity. They found that solids loading is more important than hydraulic loading. Read more
Going off the grid
A growing number of water and wastewater treatment plants (WWTPs) have incorporated more environmentally sustainable practices into their operations by buying electricity from utilities that use wind power, recovering biogas from anaerobic digesters to heat their facilities, or conducting energy audits. But few have been able to install renewable energy sources that enable them to go “off the grid” for hours or have made it possible to generate so much energy they can power their entire facility and send the remainder back to the grid. Two WWTPs — the 75th Street Wastewater Treatment Facility in Boulder, Colo., and the Lometa (Texas) WWTP — were able to do just that by installing solar arrays onsite.
Coming in the next issue:
Managing the cost of electricity is an ongoing, but doable, task. It requires a comprehensive energy management strategy to help navigate times of rising energy costs and shrinking budgets.
Managers who understand how electricity is priced and purchased can take advantage of opportunities to reduce energy costs. Many utility managers have found ways to cut their electricity costs with little or no capital investment.
When capital investments are on the horizon, past energy inflation rates can be a guide to making the smart choice. Depending on local inflation rates, a higher-priced but more energy-efficient equipment option today could easily pay for itself tomorrow as energy costs continue to rise.
The July issue highlights two types of sewer rehabilitation in King County, Wash.: emergency response and ongoing maintenance.
One sewer district in the county successfully completed an emergency sewer line repair within an environmentally sensitive, but hard-to-access, stream. The stream flow had unearthed the sewer, which was in danger of completely separating from the trunk line. The fix required immediate action, special equipment, airlifted materials, and coordination of several state and local agencies.
Another district fought back infiltration and inflow (I/I) by replacing private laterals with public money. After a pilot program of this approach led to a 74% reduction, the district leapt both legal and logistic hurdles to tighten up its collection system.
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