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BLOG: Three Types of Decentralized Wastewater Treatment Systems

Posted on by Aaron Burke, P.E.

A decentralized wastewater treatment system is an effective and efficient solution for residential, commercial, or small municipal applications as an option to centralized sewers or where connection to a centralized sewer system is not available. The decentralized approach to wastewater treatment involves the use of a treatment system that is located at or near the site where wastewater is generated, such as a small community, subdivision, school, RV park/campground, fuel station, or industrial work site. There are a variety of proven options for wastewater treatment systems. The following is a listing of three wastewater treatment system solutions for decentralized wastewater treatment: 

Conventional Septic Systems:

Conventional septic systems can be upsized for use in larger flow wastewater treatment systems. This approach incorporates the elements found in conventional septic systems for single-family homes: a wastewater storage tank and drainfield. Tanks such as Infiltrator’s IM-Series septic tanks can even be installed in-series to increase holding capacity. Due to the limited treatment capability of septic tanks, the effluent must be discharged below the ground into a drainfield comprised of chambers, stone and pipe, EZflow, or a combined treatment and dispersal solution like Advanced Enviro-Septic. Conventional septic systems are a common approach to treat daily flows above 2,000 GPD, but are limited to the soil’s ability to percolate wastewater. This case study reviews a system where Advanced Enviro-Septic was installed as part of a wastewater treatment system for a FEMA Base Camp that generated a daily flow of 100,000 GPD.

Advanced Wastewater Treatment Package Units:

Advanced treatment systems provide a higher level of effluent water quality, and discharge from these systems can be below grade, similar to conventional septic, or above grade when permitted by the NPDES program. Package systems are usually manufactured in a facility and shipped to the site where they are quickly installed and commissioned. Package treatment plants are often custom-built to meet wastewater treatment system specifications.

Suspended Growth Treatment Plants:

Suspended growth systems accelerate wastewater treatment through an aeration and oxidation process that mixes and breaks down the wastewater by the consumption of organic compounds using naturally occurring bacteria that is “suspended” in the tank as floc. The floc then settles in a clarifier, producing a clear and odor-free effluent that can be discharged above grade or below grade. This activated sludge technology is well understood and efficient in terms of aeration energy required to drive the treatment process.

Attached Growth Treatment Units:

Attached growth systems are similar to suspended growth systems except that instead of floating in the tank, the biology grows on media that is submerged in the treatment reactor. For example, the ECOPOD series from Delta Treatment Systems uses a uniquely designed media configuration and aeration pattern to accelerate biological growth and enhance wastewater treatment in the system. The main advantage of these systems is the robust nature of attached growth biology, as they are well suited to surviving the dramatic swings in diurnal flows and loads commonly experienced in decentralized systems.

In addition to a library of case studies, Infiltrator has a team of experts available to help design your next wastewater treatment system.

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About the Author: 
Aaron Burke, P.E.
Wastewater Engineer

Aaron brings 17 years of experience to the Technical Services team at Infiltrator Water Technologies. He has worked in administrative project management, construction, engineering design, and has started two wholly owned companies. His expertise is in wastewater treatment process design and treatment plant operations. Aaron holds a Bachelor’s degree in Civil Engineering from Rose-Hulman Institute of Technology and a Master’s of Engineering in Civil Engineering from Norwich University, and is a licensed professional engineer, LEED accredited professional, and certified wastewater operator.