Detection of Volatile Organic Compounds in Wastewater

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Virtually any chemical may be found in wastewater. Wastewater is any water that has been adversely affected in quality because of anthropogenic influence. Wastewater can originate from a combination of industrial, commercial, domestic or agricultural activities, stormwater or surface runoff, and from sewer inflow or infiltration.

Sewage is a type of wastewater that contains domestic wastewater and is thus contaminated with urine or feces from people's toilets, however the term sewage is also used to mean any type of wastewater.

Sewerage is the physical infrastructure, including pumps, pipes, channels, screens, etc. used to transport sewage from its origin to the point of final treatment or disposal.

Wastewater can come from a range of things such as human excreta (urine and feces), washing water (floors, cars, dishes, clothes, etc.), excess manufactured liquids from domestic sources (drinks, pesticides, cooking oil, paint, cleaning liquids, lubricating oil, etc.), urban rainfall runoff from highway drainage, roads, roofs, sidewalks/pavements, carparks, storm drains (may include trash), industrial waste, manmade liquids (illegal disposal of used oils, pesticides, etc.), industrial site drainage and many others.

The Problem

Wastewater constitutes of pathogens such as viruses, bacteria, prions and parasitic worms, organic particles such as paper fibers, hairs, food, feces, vomit, plant material, pharmaceuticals, gases such as carbon dioxide, methane, hydrogen sulfide and other hazardous substances which act as Volatile Organic Compounds (VOCs) present in wastewater.

The discharge of wastes from wastewater treatment plants (WWTPs) has highly harmful effects on the health of aquatic ecosystems.

The Solution

There are several processes that can be used to clean up wastewaters based on the type and extent of contamination. Wastewater treatment plants can be used to treat wastewater. Sewage treatment plants are in use to treat municipal wastewater. Agricultural wastewater may be treated in agricultural wastewater treatment processes, while industrial wastewater is treated in industrial wastewater treatment practices.

For municipal wastewater, the use of septic tanks and other On-Site Sewage Facilities (OSSF) is extensive in certain rural areas, for example serving up to 20% of the homes in the U.S.

One type of aerobic treatment system is the activated sludge process, based on the maintenance and recirculation of a multifaceted biomass made up of micro-organisms capable of absorbing the organic matter carried in wastewater. Anaerobic wastewater treatment processes (UASB, EGSB) are also extensively applied in the treatment of biological sludge and industrial wastewaters. Some wastewater may be highly treated and reused as reclaimed water. Constructed wetlands have also been used for this purpose.

An electronic nose for on-site measurement of VOCs in water called zNose^® has been explained. Built upon ultra-fast gas chromatography, measurements of volatile organic vapors and their water concentrations in the low part-per-billion range can be realized on-site. Separation and quantification of the separate chemicals are carried out in seconds.

Conclusion

Using a solid-state mass sensitive detector, universal non-polar selectivity, picogram sensitivity and electronically variable sensitivity has been accomplished. An integrated vapor concentrator coupled with the electronically variable detector, allow the instrument to measure VOC concentrations spanning 6+ orders of magnitude.

This information has been sourced, reviewed and adapted from materials provided by Electronic Sensor Technology.

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