Wastewater treatment is the process of taking wastewater and making it suitable for discharge back into the environment. Wastewater can be formed by a variety of activities, including washing, bathing, and using the toilet. Rainwater runoff is also considered wastewater. No matter where it comes from, this water is full of bacteria, chemicals, and other contaminants. Wastewater treatment reduces the contaminants to acceptable levels so as to be safe for discharge into the environment.
It often refers to three levels of wastewater treatment:
- Primary (mechanical) treatment is designed to remove gross, suspended and floating solids from raw sewage. It includes screening to trap solid objects and sedimentation by gravity to remove suspended solids.
- Secondary (biological) treatment removes the dissolved organic matter that escapes primary treatment. This is achieved by microbes consuming the organic matter as food, and converting it to carbon dioxide, water, and energy for their own growth and reproduction.
- Tertiary treatment is simply additional treatment beyond secondary. Tertiary treatment can remove more than 99% of all the impurities from sewage, producing an effluent of almost drinking-water quality.
This is a fast growing market with a compound annual growth rate (CAGR) around 10.5%. Main wastewater treatment technologies include:
- Physical/chemical treatment
- Biological treatment
- Mechanical equipment
- Membrane filtration including reverse osmosis
- Natural treatment systems, including wetlands
- Solids/residuals management
- Thermal systems and energy conservation
- Effluent recycling and integrated water cycle management
- Membrane Bioreactor (MBR)
MBR has the fastest growth at a CAGR around 20%, due to its smaller footprint, great modular expansion capability, reduced sludge yield, and higher quality effluent.
Nonwovens used in in wastewater treatment mainly include microfiltration, pre-membrane filtration, membrane substrates, membrane support, spacing materials, electroadsorptive nonwovens, activated carbon composites.