Occurrence and Removal of Macrolides in Municipal Wastewater Treatment Plants: A Review

Introduction: Macrolides are a group of antibacterial agents. Given their clinical importance, and the consistent rise in resistance among pathogenic bacteria, macrolides have been the targets of extensive research. Materials and Methods: This review considered the number of macrolides in different wastewater and the removal of these drugs. The antibiotics were frequently detected in influents and effluents, ranged from ng/L up to lower μg/L. In influent, the highest concentrations of clarithromycin (6080 ng/L), roxithromycin (>103 ng/L), erythromycin (3900 ng/L), and azithromycin (1949 ng/L) were detected in Croatia, Chinese, USA, and Singapore municipal wastewater treatment plants, respectively. Results: The removal efficiency of macrolides during wastewater treatment processes varies and is essentially dependent on a combination of macrolides physicochemical properties, location of municipal wastewater, and the operating conditions of the treatment systems. The application of alternative techniques, including membrane separation, activated carbon adsorption, advanced oxidation processes, biodegradation, and disinfection were the dominant removal routes for macrolides in different wastewater treatment processes. A combination of these techniques can also be used, leading to higher removals, which may be necessary before the final disposal of the effluents or their reuse for irrigation or groundwater recharge. Conclusion: Many antibiotics cannot be removed completely in wastewater treatment processes and would enter into the environment via effluent and sludge. The molecular structure of macrolides and their load-bearing capacity has led to the advantage of biological treatment over other treatments. However, the main part of the treatment has been done using biological treatment.

Type, Sources, Methods and Treatment of Organic Pollutants in Wastewater

Persistent organic pollutants (POPs), which are synthetic organic chemical compounds, either intentionally or unintentionally produced, have widely aroused public concern in recent years. These chemicals are toxic and major environmental concern due to their persistence, long range transportability, bioaccumulation and potentially adverse effects on living organisms. Uncontrolled inputs combined with poor environmental management often result in elevated levels of persistent organic pollutants in affected estuaries. Since the Stockholm Convention on POPs was adopted, different techniques have been extensively developed. A major focus revealed the need for low cost methods that can be implemented easily in developing countries such as electrochemical techniques. Persistent organic pollutants are known to be resistant to conventional treatment methods such as flocculation, coagulation, filtration and oxidant chemical treatment. However, various advanced wastewater treatment technologies such as, activated carbon adsorption, biodegradation using membrane bioreactor and advanced oxidation processes (AOPs) have been applied in the treatment of POPs.

A Short Communication on Wastewater Treatment Techniques Used in Pharmaceutical Plant

Toxic and difficult to biodegrade pharmaceutical wastewater is complex in composition with high concentrations of organic debris and microorganisms. There may still exit quantities of suspended particles and dissolved organic materials even after further treatment. Advanced treatment is required to improve the quality of pharmaceutical wastewater discharge. In this study, the pharmaceutical technology categorization has been established, and the features of pharmaceutical wastewater effluent quality have been summarized. On the other hand, The methods of advanced treatment of pharmaceutical wastewater have been incorporate, including coagulation and sedimentation, flotation, activated carbon adsorption, membrane separation, advanced oxidation processes, membrane separation, and biological treatment. In the meanwhile, each process's features were specified.

Removal of metronidazole antibiotic from aqueous solution by ammonia-modified activated carbon: adsorption isotherm and kinetic study

This article was aimed at investigating the removal of metronidazole (MNZ) from aquatic solutions by modified activated carbon (MAC) with amine groups. The effect of various parameters on the adsorption rate such as the initial pH, adsorbent dose and initial concentration of MNZ and contact time were scrutinized. MAC was characterized by Fourier transform infrared spectroscopy and Brunauer–Emmett–Teller techniques. The obtained results illustrated that under the optimum conditions (pH = 3, contact time = 50 min, initial MNZ concentration = 5 mg/L and MAC dose = 0.5 g/L), the maximum adsorption efficiency was 95%. Furthermore, the kinetic studies indicated the applicability of the pseudo-second-order kinetic model, whereas the adsorption isotherm fitted well with the Freundlich model (0.996), and the maximum adsorption capacity was 66.22 mg/g. The SBET and the total pure volume of MAC were 706.92 m2/g and 0.532 cm3/g, respectively. Also, the regeneration tests demonstrated that MAC had good stability after five cycles (73%). It can be concluded that MAC, as an effective adsorbent, has a high ability to remove MNZ from aqueous solutions.

Nitrate Adsorption by Activated Carbon

Activated carbon is a type of carbon that is a known catalyst for a variety of chemical reactions. Uses of activated carbon include purifying liquids and gases, food and beverage processing, odor removal, industrial pollution control, and numerous other applications. There are a variety of different activated carbons, with most being derived from coal, peat, and wood. Activated carbon is a catalyst because the small pores of the carbon increase the surface area available for adsorption or chemical reactions. One primary use of activated carbon is how it adsorbs nitrates onto its surface. This paper delves into different adsorption rates of an activated carbon (Filtrasorb 600) that is treated with different chemicals and then subjected to a chemical activation at a constant pressure under different gaseous conditions. Data collected during experiments indicate there are significant interactions between surface functional groups and nitrate. Keywords: activated carbon, adsorption, nitrates

Comparison and predesign cost assessment of ozonation, membrane filtration and activated carbon for the treatment of recalcitrant organics, a conceptual study

The presence of micropollutants in the environment is today of major concern. These pollutants could have long-term impacts on the environment and on population health. Biological treatment of wastewater is generally insufficient to allow their complete elimination. The establishment of efficient treatments is then needed to degrade the refractory organic matter. Activated carbon adsorption, membrane filtration and oxidation processes are common suitable solutions. All of them have advantages and are effective to treat wastewaters but drawbacks are well known such as waste production, energy consumption or by-products formation. This study aims at defining a strategy to choose the best option according to the nature of the wastewater and the treatment objectives. A methodology was designed for the rating of theses processes to choose the best strategy regarding environmental, technical and economic criteria. A simulation of three wastewater treatment scenarios was carried out to compare the costs of ozonation, adsorption and reverse osmosis. According to the result obtained, a decision tree is proposed to define the best option for a tertiary treatment to reach reuse or discharge objectives.

Separation and characterization of lignin and sugars in the hydrolysate of hot water extraction of poplar wood by membrane filtration and activated carbon adsorption

Hot water extraction of poplar wood was conducted at temperatures from 190 to 200 °C for 5 to 8 min. A hemicellulose yield of 81% and a lignin yield of 38% were obtained at 200 °C for 8 min. A combined process of microfiltration, ultrafiltration, and activated carbon adsorption was developed to separate lignin and sugars in the hydrolysate of hot water extraction. Lignin recovery efficiencies of 56.7%, 26.0%, and 13.2% were attained for microfiltration, ultrafiltration, and activated carbon adsorption, respectively. The characterization of lignin revealed diversity in molecular weight and functional groups, which is beneficial for high-value valorization. The obtained hemicellulose sugars from the combined process showed a good recovery rate of 43.8% and remarkable purity of 97.5%. The purified sugars were a mixture of monomers and oligomers that consisted of arabinose, galactose, xylose, glucose, and mannose. Sugar oligomers with degrees of polymerization from 2 to 6 accounted for 21.6% of all sugars.