Wastewater Treatment Methods
This discussion of the treatment of wastewater is designed to inform and will hopefully serve as a useful guide when selecting from the variety of methods and sewage treatment systems currently on the market.
As you probably realize, the sewage treatment of wastewater can be a costly and difficult business. Once wastewaters are discharged from a property, sewage treatment becomes a must for many property owners, especially in rural areas where there may be a high water table or a water course nearby.
On- site or communal sewage treatment?
An on-site sewage treatment plant (also known as a waste water treatment plant) that serves your property only is always the best option since it becomes much easier and less expensive to repair and the knock-on effects of any breakdown are considerably reduced.
But it may be the case that an on-site sewage treatment system is not possible because of the ground conditions in your area, and if so you may need to look at having an off-site treatment plant.
Disposal of solids.
All domestic and commercial sewage treatment plants will need de-sludging or the solid waste removed every so often. This is something you will have to consider when positioning a waste water treatment plant, since it is vital that there is sufficient access for the tankers that emptying companies use and that their hoses can reach your plant – its best to phone around and find out how far they can reach and how much access is required.
Waste water treatment options
Interestingly very few sewage treatment plants actually work, but the good news is that there are some that do!
Here is a brief summary of the options available.
1. Activated sludge process
This is where oxygen is supplied mechanically in order to feed the bacteria which breaks down the organic materials.
This can be quite a sophisticated process, at times with lots of moving parts (such as the Klargester Biodisc system) but it can provide a high degree of treatment.
2. Aerated Lagoons
Very similar to the WSP method discussed (8) below but with forced aeration.
Not very often used in the UK and can be very costly to maintain.
3. Land Treatment (Soakaway)
Sewage flows in to the ground and is treated by the soil.
Soil treats sewage very well in domestic properties where there is a low concentration of chemicals.
4. Oxidation ditch
A large channel with aeration feed.
Requires a large amount of power but can work with less land than the WSP.
5. Reed Beds (constructed wet lands)
Sewage passes through the area of reeds and is treated.
Like a soakaway the wastewater is treated by the soil and the ground also does not require oxygenation.
6. Rotation biological contractor (Klargester Biodisc)
Uses a series of slim disks to supply surface area for the oxygen.
Treatment is a conventional aeration process but can be expensive to repair.
7. Percolation filters
Waste water passes down through a membrane or a rock filter and the bacteria on the surface treats the sewage.
No need for mechanical aeration but can have moving parts.
8. Waste Stabilisation Ponds (WSP)
Large surface area of ponds.
Treatment takes place by means of sunlight action, stimulating algal grottoes that provide oxygen to the water, no power needed - just a large area, but it can pong a bit!