Pharmaceuticals removal from hospital wastewater by fluidized aerobic bioreactor in combination with tubesettler

Introduction

Pharmaceuticals are ubiquitous in our daily lives, but their presence in wastewater poses a significant threat to environmental health. The contamination of water bodies by micropollutants, particularly pharmaceutical compounds, has become a pressing concern. These compounds are present in wastewater at concentrations as low as nanograms per liter (ng/L) to micrograms per liter (µgL− 1), making their removal a challenging task for conventional treatment plants. Recent studies have highlighted the effectiveness of fluidized aerobic bioreactors combined with tube settlers in removing these micropollutants from hospital wastewater, offering a promising solution to this environmental issue.

The Problem: Micropollutants in Wastewater

Micropollutants, especially pharmaceutical compounds, are of significant concern owing to their ngL− 1 to µgL− 1 concentration, making them difficult for conventional treatment plants to remove from wastewater. These compounds include a variety of pharmaceuticals such as fluvastatin, ketoprofen, paracetamol, ciprofloxacin, carbamazepine, sulfamethoxazole, and lorazepam, which are commonly used in hospitals and other healthcare settings. The continuous occurrence and persistence of these micropollutants in water/wastewater systems pose a substantial risk to aquatic life and human health.

Conventional Treatment Methods: Limitations

Conventional wastewater treatment plants primarily use activated sludge processes, which are effective for removing organic matter and nutrients but often fail to completely eliminate micropollutants. Advanced oxidation processes (AOPs) and adsorption methods have also been employed, but they come with their own set of drawbacks, including high costs, energy consumption, and the creation of additional harmful by-products. The inadequacy of these methods in removing micropollutants underscores the need for more advanced treatment technologies.

Fluidized Aerobic Bioreactors: A Novel Approach

Fluidized aerobic bioreactors (FABs) have emerged as a novel approach for treating hospital wastewater. These reactors use a fluidized bed to enhance the interaction between microorganisms and the wastewater, thereby increasing the efficiency of pollutant removal. The addition of a tube settler to the FAB system allows for more effective separation of solids from the effluent, making it suitable as a polishing unit rather than a secondary clarifier.

Advantages of Fluidized Aerobic Bioreactors

1. Efficient Pollutant Removal: FABs are particularly effective in removing a wide range of micropollutants, including pharmaceutical compounds. The fluidized bed ensures that microorganisms are constantly exposed to the pollutants, enhancing their biodegradation.

2. Low Energy Input: FABs operate with relatively low energy input, which makes them more cost-effective compared to other advanced treatment methods. This is crucial for hospitals and healthcare facilities that need to manage wastewater efficiently without incurring high operational costs.

3. No Clogging Issues: Unlike traditional bioreactors, FABs are not susceptible to clogging during operation. This makes them more reliable and easier to maintain, reducing downtime and ensuring continuous treatment.

4. Recovery of Metals: The fluidized bed process allows for the recovery of metals from the wastewater, which can be reused or disposed of properly. This aspect contributes to the overall sustainability of the treatment process.

The Role of Tube Settlers

Tube settlers are an integral part of the FAB system, enhancing the separation of solids from the effluent. This step is crucial for producing a clear and pollutant-free effluent. The settlers work by allowing the fluidized particles to settle under gravity, reducing the need for secondary clarifiers and improving the overall efficiency of the system.

Case Studies and Findings

Several studies have been conducted to evaluate the performance of fluidized aerobic bioreactors in removing micropollutants from hospital wastewater. One such study focused on treating wastewater containing fluvastatin, ketoprofen, paracetamol, ciprofloxacin, carbamazepine, sulfamethoxazole, and lorazepam. The results showed that the FAB system was able to effectively remove these pharmaceutical compounds, reducing their concentration in the effluent to acceptable levels.

Another study compared the efficiency of aerated and non-aerated constructed wetlands in removing micropollutants. The findings suggested that fluidized aerobic bed bioreactors had a significant advantage over constructed wetlands due to their ability to handle high organic loads and recover metals.

Challenges and Future Directions

While fluidized aerobic bioreactors combined with tube settlers show great promise in removing micropollutants from hospital wastewater, there are several challenges that need to be addressed.

1. Scalability: The current design of FABs may not be suitable for larger-scale applications, particularly in developing economies where space is limited. Further research is needed to develop scalable versions of these bioreactors.

2. Toxicity Reduction: Additional studies are required to analyze degradation pathways and products generated from pharmaceutical compounds after treatment. This will help determine whether the treated wastewater has decreased in its toxicity or not.

3. Integration with Other Technologies: Combining FABs with other treatment technologies such as adsorption and oxidation processes might be desirable to achieve more efficient removal of micropollutants.

Conclusion

The removal of micropollutants, especially pharmaceutical compounds, from hospital wastewater is a critical issue that requires innovative solutions. Fluidized aerobic bioreactors combined with tube settlers offer a promising approach by enhancing the efficiency of pollutant removal, reducing energy input, and minimizing clogging issues. While there are challenges related to scalability and toxicity reduction, ongoing research is addressing these limitations. As we move forward, integrating these bioreactors with other treatment technologies will be essential for achieving sustainable and effective wastewater treatment solutions.

References https://link.springer.com/article/10.1007/s13762-023-04867-z https://www.sciencedirect.com/science/article/abs/pii/S2213343721008733 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9359512/ https://www.nature.com/articles/s41598-024-73494-6

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This article highlights the importance of addressing the issue of micropollutants in wastewater through innovative treatment technologies like fluidized aerobic bioreactors combined with tube settlers. By understanding the advantages and challenges of these systems, we can move closer to ensuring the sustainability of our water environment.