The American Academy of Environmental Engineers and Scientists (AAEES) recently selected American Engineering Consultants, Inc. (AEC), a Cayce, South Carolina firm, as the recipient of the 2014 Grand Prize for its Excellence in Environmental Engineering & Science™ (E3) competition for Small Firms. AEC‘s entry, titled “Membrane Thickening – A Sustainable Solution”, showcased their innovative wastewater treatment design for the City of Cayce’s new 25.0 Million Gallon per Day (MGD) Regional Wastewater Treatment Facility. Recipients are chosen by a panel of distinguished experts and signify today’s best firms in environmental engineering and science. The award was presented to William H Bingham, Jr., PE, President of AEC, on April 24th at the Academy’s Annual Awards Luncheon and Conference held at the National Press Club in Washington, DC. Mr. Bingham stated, “This award is a validation of the hard work and devotion that our team has given to this project and represents the pinnacle of success for our firm. We are profoundly honored to be recognized by our national peers as one of the best environmental engineering firms in the country and deeply grateful to the City of Cayce for placing their trust in us.”
American Engineering Consultants provided complete engineering design and construction administration for the new $56 Million dollar wastewater treatment facility constructed along the Congaree River and serves municipalities and industries throughout Lexington County in SC.
The effluent from the plant is regulated to strict standards by state and federal regulators to protect the river. To comply with those regulations, the facility utilizes multi-staged biological reactors to remove pollutants, including the nutrients, nitrogen and phosphorus, from the wastewater before its discharge into the river. Biological nutrient removal (BNR) is a process whereby a variety of living microscopic organisms are grown in large tanks or reactors in a very watery mixture known as “activated sludge” that treats the wastewater. Within the activated sludge there are some bacteria that breakdown ammonia and other nitrogen compounds into inert nitrogen gas, which is vented harmlessly into the atmosphere. The activated sludge also contains other organisms that consume the phosphorus and feed on other pollutants in wastewater. With wastewater being continuously fed into the reactors, the organisms are constantly working, eating, and reproducing. As a result of their reproduction, some of the activated sludge must be removed from the reactor (wasted) to prevent an accumulation of excess activated sludge. The excess activated sludge (biosolids) must be treated and dewatered before disposal via landfilling or land application. If the wasted biosolids are not kept under aerobic conditions (supplied with air/oxygen) continuously, the biosolids will release the phosphorus that they consumed in the biological reactor back into the liquid wastewater stream nullifying the benefits of biologically removing the phosphorus.
American Engineering’s design features a unique and sustainable biosolids handling process that overcomes the problem of phosphorus release during the thickening and digestion operation. The largest installation of its type in the world, this process utilizes flat plate membrane technology to achieve liquid-solids separation while simultaneously thickening and digesting the biosolids. The watery biosolids mixture is passed over the surface of the membrane units where a portion of the liquid is continuously being filtered through the membrane material, leaving behind concentrated biosolids the consistency of a thin pudding, without the use of costly chemicals. The liquid filtered out from the membrane process is clean water of reuse quality and can be used directly as a source of non-potable water for use in irrigation and other process applications within the plant. Requiring only minimal operator attention, this fully automated process maintains aerobic conditions in the biosolids while continuously thickening and digesting, thereby preventing the release of the biologically removed phosphorus. Once dewatered using a centrifuge, the biosolids have the consistency of crumbled up moist cake or brownies and contain all the phosphorus and other pollutants removed from the wastewater. The dewatered biosolids are considered Class B and can be disposed of in a landfill or land applied as a soil conditioner and fertilizer.
As an AAEES Grand Prize winner, this project automatically qualifies for the upcoming 2014 International Water Association (IWA) Project Innovation Awards (PIA) Global Competition. The winners of this esteemed international competition will be announced during the IWA World Water Congress and Exhibition in Lisbon, Portugal from September 21-26, 2014.