C+S April 2021 Vol. 7 Issue 4 (web)

The settled sludge returns from the clarifier floor sludge well to the aeration chamber by the positive sludge return system. Immediately following the clarifier is a plug flow chlorine contact chamber. The influent characteristics were typical domestic waste loadings, with ef- fluent requirements of less than 20 mg/L BOD/TSS. Delta was faced with the challenge of manufacturing a treatment system that would maintain the footprint boundaries of the existing system, while providing treatment with more stringent effluent qual- ity requirements. Additionally, given the location and importance of esthetics in this highly traveled vacation area, the owners wanted the system tucked away and virtually unnoticeable by the residents of the resort, so a building was constructed around the unit. Conclusion Asking the right questions and drawing from available research and data can make or break the wastewater treatment system design pro- cess and ensure long-term performance. Most industry professionals are willing to discuss projects and provide support. Additionally, manufacturers or advanced wastewater treatment technology have dedicated technical support teams that are readily available to provide background and suggest the best solution for your large-scale waste- water system challenge.

as an engineered chamber system, can extend the life and community investment in the WWTF and have the added benefit of reducing phos- phorus and eliminating outfall discharges to bodies of water. And, most centrally managed decentralized wastewater treatment sys- tems, such as publicly- and privately-owned community systems, are being staffed with trained and educated personnel in the same manner as centralized systems. Natural processes and functions provide holistic benefits When reintroduced into the design of semi-urbanized environments, green infrastructure that uses vegetation and soil to reduce rainwa- ter runoff volume may also reduce air pollution and air temperature through evapotranspiration. This can help to minimize the urban heat island effect, while at the same time providing ground cover that serves a habitat function. Designing with nature can also be seen in a larger sense, as land development that is more sustainable – economically, environmentally, and socially. Technology in Action Lauloa Maalaea Resort Utilizes Extended Aeration System to Up- date Wastewater Treatment To meet more stringent effluent regulations for a permit update and handle the design flow of 21,000 gallons per day, the Lauloa Maalaea Resort in Hawaii was required to update their wastewater treatment system. The Resort selected a new Delta Extended Aeration Treatment Unit which had to be installed in the same location of the existing be- low grade system. The extended aeration process selected for this system utilizes aeration followed by clarification and disinfection. The flow equalization cham- ber receives the incoming wastewater then duplex pumps discharge the wastewater into the aeration chamber. Duplex positive displacement blowers and an air distribution manifold system supply all the air needs to the system including air diffusers, airlift pumps, and a scum skim- mer. The hopper-style clarifier chamber has baffling to prevent short circuiting and to provide the maximum uniform solids settling area.

DENNIS F. HALLAHAN, PE has more than 30 years of experience with onsite waste- water treatment systems’ design and construction. Currently Technical Director at Infiltrator Water Technologies, he is responsible for technology transfer between Infiltrator and the regulatory and design communities and consults on product research and testing for universities and private consultants. Hallahan received his MS in civil engineering from the University of Connecticut and his BS in civil engineering from the University of Vermont. He is a registered professional engineer in Connecticut and holds several patents for on-site wastewater products. He can be reached at dhallahan@infiltratorwater.com.



April 2021

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