We flush the toilet or pour something down the drain and it goes away and you think nothing more about it, right? Well, in essence, it only goes out of your sight. It does not just disappear; it goes into the sewage system and wastewater. It’s not only homes and offices we are talking about here, it is factories, and industries such as pharmaceutical, biomedical, chemical and textile that have to deal with wastewater. Therefore, wastewater is becoming very complex to deal with due to the wide variety of pollutants and this call for advancement in wastewater treatment.
What is advanced wastewater treatment?
In short, advanced wastewater treatment is a process taken as an intermediate step in the treatment of sewage. This step is in-between the primary and initial treatment stages, using more advanced technologies than used in standard wastewater treatment. The standard sequence of processes used in the treatment of wastewater is:
- Preliminary treatment;
- Primary treatment;
- Secondary treatment;
- Tertiary treatment.
Advanced wastewater treatment is a process used when the sewage that has been produced is unable to be treated efficiently in such as a septic tank, effluent tank or trash tank. The advanced treatment removes faecal coliform, nitrogen, solids, contaminants and nutrients effectively from the wastewater.
There are numerous types of advanced wastewater treatments used and these depend on the type of matter to be removed from the wastewater.
Suspended solid removal
To help in the removal of suspended solids advanced wastewater treatment includes:
- Chemical coagulation and clarification;
- Micro screening;
- Ultrafiltration.
Removal of phosphorus:
To help with the removal of phosphorous processes include:
- Chemical coagulation and clarification;
- Chemical precipitation and clarification.
Organic matter removal:
To help with organic matter removal:
- Adsorption using activated carbon;
- Biological oxidation.
The advanced oxidation process:
The advanced oxidation process is one such form of advanced treatment. Today there are stringent treatment standards, and the biological methods that were once applied, including evaporation and incineration are now falling short due to causing secondary pollution. Advanced oxidation plays a huge role in ensuring industries can meet treatment standards. Advanced oxidation can be used alone or through a biological process.
Advanced oxidation is said to be the key to future sustainable success within the chemical industry thanks to its having:
- A small footprint;
- High flexibility;
- Nonselective destruction of pollutants.
The difficulties advanced oxidation technologies pose:
One of the main difficulties using advanced oxidation technologies poses is the fact that it is extremely difficult to apply an advanced oxidation technology solution from industry to industry.
Even more complicated is the fact that there can also be difficulties when applying the same technology in different wastewaters within the same industry.
Essentially, a structured approach is needed to identify the correct oxidation treatment technology for every single industry.
One solution is design thinking:
One approach to this, and a solution, is design thinking. This is a complex thinking process made up of several stages:
- Define;
- Research;
- Ideate;
- Prototype;
- Choose;
- Implement;
- Learn.
From using the above approach problems can be uncovered, questions asked, ideas are created and finally the best solution is chosen.
The biggest issues related to wastewater:
Of course, it is also important to have a clear understanding of the nature of wastewater, along with the pollutants that reside in it.
The biggest issues with wastewater and wastewater treatment are:
- Heavy metals;
- Biorefractory compounds;
- pH;
- Phenols;
- Ineffective primary treatments;
- Solvents;
- A lack of space.
The biggest problem lies in clearly defining the nature of the problem; otherwise, the right advanced oxidation process can’t be selected.
Industries differ significantly, for instance, textile-processing industries are generally associated with high volume and low COD wastewater. The wastewater is easy to treat biologically; however, the issue lies with space.
Once the problem has been defined, the correct combination of treatment technologies can be used for wastewater treatment, based on the advanced oxidation processes.
The technology is extremely effective in regards to reacting with and destroying emerging contaminants. However, the downside is that it is an expensive alternative form of disinfection for treating drinking water.
Advancements in oxidation technology:
On the plus side new effective solutions are being developed that are also cost-efficient. A company in the USA developed advanced oxidation technology making use of a HiPOx process that is ozone-based, which degrades compounds including personal care by-products and pharmaceutical products.
The use of advanced oxidation based on ultrasound is gaining momentum due to the efficiency in the removal of contaminants. Ultrasound technology may either be used as a standalone process or when combined with further oxidising agents. The latter enhances the remediation process.
Photocatalysis and AOP are effective:
The combination of photocatalysis and AOP is continuing to stir up interest in wastewater treatment thanks to the high removal of degrading organic pollutants from the wastewater.
This process is friendly to the environment when compared to other treatment processes. Photocatalysis processes are regarded as having potential for use in wastewater that has come from the treatment of hazardous waste.
Of course, biological methods cannot be used on any pollutants refractory in nature. They have to be destroyed through the incineration process. The majority of wastewaters rely on a range of treatment technologies, from biological to incineration and often they need a combination of treatments.
As you can see, getting from wastewater to reusable water takes a great deal of thought.
Advanced oxidation processes are one of the most favourable options to ensure organic pollutants are effectively removed from wastewater. This is great news considering numerous harmful chemicals get released in effluent from industries. Without effective removal, the chemicals in wastewater are a human health risk and a risk to the environment.
In summary:
There have been numerous advancements in wastewater treatment technology and the more technology advances, the better plants are becoming at removing dangerous chemicals and substances from wastewater.
With an eye on the environment, more than ever effective wastewater treatment is of the utmost importance. Businesses, councils and municipalities want to recycle water, instead of continually drawing on clean water sources and thanks to continual advancements in processes and technology the future is looking brighter.