Activated Sludge Process is a common (biological treatment) method that leverages microorganisms to degrade organic compounds in the wastewater. But the ability to break down the pollutant varies. Drugs like sulfamethoxazole (antibiotic), ibuprofen and acetylsalicylic acid (a breakdown product of Aspirin) degrade within 2-5 days up to 98%; antiepileptic like gabapentin at least partially degrade. Roxithromycin (antibiotic) on the other hand, needs 5-10 days to degrade, while drugs like Carbamazepine (anti antiepileptic drug) and Diazepam (psychoactive drug) have shown no significant degradation even after 20 days. Therefore, alternative methods are required to destroy trace amount of toxic drugs in the wastewater. 

Another viable solution for PWW treatment is an advanced membrane process to remove or concentrate the drugs from the wastewater. Two widely used membrane technology are Nano Filtration and Reverse Osmosis. Again, the effectiveness varies depending on the characteristics of the waste in question. With a pore size of 0.002 micrometers (2nm), a typical Nano Filtration filter is able to remove most organic substances, almost all viruses, other organic molecules and a range of salts but lacks when it comes to rejecting pollutants with a lower molecular weight. Those can be addressed by using the pressure-driven membrane filtration called Reverse Osmosis (typical filter pore size of 0.1nm). A membrane process has a lower footprint, is quick to build with standardized ready-to-use system available and therefore easier to accommodate in existing facilities. However, both the equipment and its energy-intensive operation are costly and this treatment is not a destruction process but merely separates and concentrates the pollutant. Some kind of destruction process (thermal/chemical/aerobic oxidation) is required to remove it afterwards and the concentrate needs to be hauled out or evaporated for a zero liquid discharge. 

An Advanced Oxidation Process (AOP) is a method that either destructs the pollutant or converts non-biodegradable into biodegradable. AOP is an answer to most refractory drugs that escape aerobic oxidation, chemical oxidation or membrane process. 

Based on the characteristics of the drug residue in the wastewater, multiple treatment options are available. But each of them brings its own advantages and disadvantages: They address only certain types of waste and might have to be combined to effectively prevent water contamination. Or they are expensive to implement and operate – even though parts of the investment might be recovered by recycling the water for non-critical processes. Especially when upgrading existing facilities, space constraints have to be taken into account as well. 

Exyte is able to provide the full scope of services required for such projects: analyzing the environmental situation and conducting a process study, developing a concept and later a detailed design, undertake the necessary constructions and installations and even commissioning and certifying the complete system. Leveraging its global network of engineers and technologists, located in all major regions (APAC, EMEA, AMER) and well-connected with equipment manufacturers and technology providers, Exyte can identify, test and finally implement an optimal solution for each project. 

Regulations often enough don’t leave much of a choice anyway, but the protection of the environment in which we live and work should be in our all best interest. Exyte is committed to this protection and feels well positioned to support our client’s efforts in this regard with a complete scope of services and global engineering expertise. 

 

About Maheswaran Nair  

Maheswaran Nair is a Chemical Engineer with over 30 years of experience in Water and Wastewater Treatment in Advanced Technology Facilities and Life Science industry segment. He has been a key member of technical team for several projects involving highly advanced High Purity Water and Wastewater sys-tems in Singapore, Malaysia, Unites States and China.