Diffuser (sewage)

An air diffuser or membrane diffuser is an aeration device typically in the shape of a disc, tube or plate, which is used to transfer air and with that oxygen into sewage or industrial wastewater. Oxygen is required by microorganisms/bacteria residents in the water to break down the pollutants. Diffusers use either rubber membranes or ceramic elements typically and produce either fine or coarse bubbles.

Contents

Types of Diffusers

Diffusers are generally referred to as either:

  1. Fine Bubble/Fine Pore
  2. Coarse Bubble

Other diffused aeration devices include: jet aerators, aspirators, and U tubes.[1]

Design Specifications

Typical efficiency of a full floor coverage diffused aeration system in clean water is 2%/ft submergence or 6.6%/m submergence. When converted to mass transfer into process or dirty water, it is typically closer to about half of those figures. Manufacturers of fine bubble systems have supported claims that the type, number and size of "pores" have a great effect on efficiency of a diffused aeration system.[2]

Types of diffused aeration systems

Diffusers are typically connected to a piping system which is supplied with pressurized air by a blower. This system is commonly referred to as a diffused aeration system or aeration grid

There are two main types of diffused aeration systems, retrievable and fixed grid, that are designed to serve different purposes. In the case of a plant with a single tank, a retrievable system is desirable, in order to avoid stopping operation of the plant when maintenance is required on the aeration system. Fixed systems, on the other hand, are typically less costly, and often more efficient because it is easier to make full use of the floor.

Automated software is available on the web to assist with drafting of aeration systems in CAD, as well as calculation software to help determine diffuser requirements for a given wastewater.

Developments in Membrane Coatings

A developments in recent years has been surface coatings of PTFE on EPDM membranes. This provides a buffer between the EPDM substrate and wastewater, hence reducing the likelihood of chemical attack and oxidation, and also providing better resistance to biological fouling and calcium scaling (manufacturers claim).[3]

References

  1. ^ http://www.epa.gov/owm/mtb/fine.pdf
  2. ^ http://www.wastewater.com/pdf/142.pdf
  3. ^ http://www.stamfordscientific.com/ptfemembranes.html

External links


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Diffuser — can refer to any device that diffuses in some manner such as: In aerodynamics Diffuser (automotive), a shaped section of a car s underbody which improves the car s aerodynamic properties divergent part of the flute[clarification needed] divergent …   Wikipedia

  • Sewage treatment — The objective of sewage treatment is to produce a disposable effluent without causing harm to the surrounding environment, and also prevent pollution.[1] Sewage treatment, or domestic wastewater treatment, is the process of removing contaminants… …   Wikipedia

  • diffuser — /di fyooh zeuhr/, n. 1. a person or thing that diffuses. 2. (in various machines or mechanical systems, as centrifugal pumps or compressors) a device for utilizing part of the kinetic energy of a fluid passing through a machine by gradually… …   Universalium

  • Activated sludge — is a process dealing with the treatment of sewage and industrial wastewaters.cite book | author=Beychok, Milton R. | title=Aqueous Wastes from Petroleum and Petrochemical Plants| edition=1st Edition | publisher=John Wiley Sons Ltd | year=1967 |… …   Wikipedia

  • Coarse bubble diffusers — PVC MaxAir coarse bubble diffuser in concrete basin. Courtesy of Environmental Dynamics Inc. Coarse bubble diffusers are a pollution control technology used to aerate and or mix wastewater for sewage treatment. They produce 1/4 to 1/2 inch… …   Wikipedia

  • Marine outfall — A marine outfall is a pipeline or tunnel that discharges municipal or industrial wastewater, stormwater, combined sewer overflows, cooling water, or brine effluents from water desalination plants to the sea. Usually they discharge under the sea s …   Wikipedia

  • Deer Island Waste Water Treatment Plant — Aerial view, Deer Island Wastewater Treatment Plant, 2010. Photo by Doc Searls …   Wikipedia

  • building construction — Techniques and industry involved in the assembly and erection of structures. Early humans built primarily for shelter, using simple methods. Building materials came from the land, and fabrication was dictated by the limits of the materials and… …   Universalium

  • Aeration — is the process by which air is circulated through, mixed with or dissolved in a liquid or substance.Methods of aeration of liquidsAeration of liquids (usually water) is achieved by: * passing the liquid through air by means of fountains, cascades …   Wikipedia

  • Desalination — This article is about removing salt from water. For soil desalination, see Soil salinity control. Water desalination Methods Distillation Multi stage flash distillation (MSF) Multiple effect distillation (MED|ME) Vapor compression (VC) Ion… …   Wikipedia


Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.