How Wastewater Gets Recycled
Water is the most precious liquid known to man. It covers the majority of our planet, makes up the majority of our bodies and the bodies of all living creatures, and is involved in practically all processes, natural or man-made. No other fluid can truly replace water.
But clean, potable water is becoming a rarity. Most of it is literally being flushed down toilets. The need to recycle and reuse water has become apparent, which is why these days water treatment facilities are so significant.
The primary goal of water treatment facilities is to separate and treat waste from wastewater to not only produce good, clean and reusable water but useful sludge as well- sludge being the combined solid waste collected from wastewater. So how is this done?
Water Treatment Process
The first step in wastewater treatment is collection. Wastewater is collected from different sources: from toilets, sinks, showers, washing machines and even rainfall. Once collected, this water passes through screens that remove large debris such as papers, boxes, sticks and the like.
After the removal of large debris, the water is then allowed to sit in large tanks known as grit tanks. It is here that smaller particles or grit is allowed to settle to the bottom while lighter particles, oil and grease float to the top. The settled grit or sludge and the oil and other floating matter are removed and disposed of in landfills, or treated separately for other purposes.
Once all the large particles have been removed, the second and slightly more sophisticated part of water treatment begins.
Micro-organisms which occur naturally in the water break down and consume organic matter in the water, but in order to do this there must be a sufficient amount of oxygen dissolved in the water. To aid this process, the water may be passed through beds of stones where biological films formed by the micro-organisms on the surface of the stones remove small organic matter.
Large water treatment infrastructure suppliers like Tenix provide another method for this, and that is with the use of aeration tanks. The water is placed in large aeration tanks and oxygen is distributed in the water through mechanical pumps or bubble diffusers located at the bottom of the tank. With the abundant supply of oxygen the removal of organic matter speeds up, and the water can then move to the next step of the treatment process.
To separate the micro-organisms and other remaining matter from the treated water, the water is allowed to settle once more in a settlement tank, where the sludge that settles at the bottom of the tank is removed. In other treatment facilities like those found in Singapore and in the U.S., the water goes through a microfiltration process, where a fine membrane separates these micro-organisms and other remaining particles.
In the last stages of treatment, the water is disinfected with chlorine, undergoes reverse-osmosis or is exposed to ultra-violet light in order to remove any traces of organic matter. From there it is then sent to water distribution systems or back into the environment.
What about the Sludge?
Clean water is not the only valuable resource that is produced from the treatment process. A considerable amount of sludge is produced as well, and though most may view it as nothing more than garbage, it is actually a very nutrient rich mixture that may be used in a number of applications after treatment:
- In agriculture, biosolids (the solid, final form of sludge after treatment) are used as potent fertilisers and soil conditioners.
- Biosolids are a very vital factor in land reclamation. They are used to make once neglected and unproductive lands useful and productive.
- The decomposition of sludge can produce biogas which can be used as fuel. Dried and burnt, sludge may also be used as a replacement for fossil fuel, in both cases supplying useful energy and heat.
Water treatment processes may be the world’s best solution to steadily depleting natural potable water sources and water pollution. It not only gives us clean water, it also replenishes the earth and helps restore balance in nature.
Debra Wright blogs about a plethora of topics including wastewater treatment and its benefits to businesses. Wright considers Tenix as one of the leading providers of wastewater infrastructure solutions.
Image courtesy of Flickr.