The purpose of this article is to review the current physical, chemical and hybrid technologies practices employed in the removal of pharmaceuticals from liquid effluents originating from various resources including municipal waste, hospitals discharge with a focus on pharmaceutical manufacturing industry. Pharmaceutical pollutants are mostly persistent organic compounds that are not easily removed by conventional wastewater treatment processes. The literature reviewed shows that advanced oxidation processes are able to degrade these persistent pharmaceuticals. However, the oxidation may also introduce toxic oxidation intermediates/byproducts if these processes are not properly monitored and operated. Physical treatments, like carbon adsorption and membrane filtration, can provide a barrier that prevents both parent compounds and toxic intermediates passing into treated wastewater. However, these processes are phase changing technologies in which contaminants are transferred from one phase to another hence, the retentate water and absorbent require further treatment, and properly managed disposal. The combination of different processes can be an ideal treatment scheme, for the retention and degradation of both parent and transformation compounds. Through hybrid technologies, the advantages of the methods are combined, leading to a maximization of contaminants removal. The review highlights the importance of installing combined wastewater treatment processes to reduce the amounts of pharmaceutical residues before the wastewater enters the environment. The use of advanced oxidation process, either as a pre-treatment or as a post-treatment combined with biological, adsorption, or filtration process is recommended as a promising option. Nevertheless, the optimum treatment methods for the pharmaceuticals-containing wastewater depends on the quality and quantity of wastewater, as well as on the pharmaceutical compounds residues and their hazardous effects.

This paper investigates the adsorption of organic compounds in aqueous solution to biochar adsorbent, using methylene blue as an indicator for adsorption. Biochar was produced by the pyrolysis of mixed municipal discarded material in an innovative heat pipe reactor, the pyrolysis temperature was held at 300°C for 12 h. Biochar produced under these conditions was found to have oxygen containing functional groups that are beneficial to the adsorption of methylene blue as well as graphitic structures suggesting potential sites for π-π interactions with methylene blue. Methylene Blue followed the pseudo second order kinetic model with higher R2 values than both the pseudo first order kinetic and intraparticle diffusion models. The adsorption also closely fit the Langmuir isotherm rather than the Freundlich model, suggesting monolayer adsorption rather than multilayer adsorption. Maximum adsorption capacity was observed at 7.2 mg/g for initial concentration of 100 mg/l Methylene blue in aqueous solution. The amount of Methylene blue adsorbed increased with increasing initial concentration as expected. The adsorption mechanisms are likely π-π interactions between methylene blue and the graphitic structures in the biochar which are shown to be present in Raman spectroscopy, as well as electrostatic attraction and ionic bonding between negatively charged surface sites on the char and the positive charge on the dissolved methylene blue molecules. The results show that biochar obtained from mixed waste could be employed as a low-cost and effective tool in water treatment for the removal of basic dyes and potentially other organic impurities.

An issue of significant importance worldwide is the contamination of water with antibiotics giving rise to antibiotic resistance in the environment. Antibiotics such as tetracycline are widely used in agriculture, as such they can pollute water courses, providing a means by which environmental bacteria can evolve antibiotic resistance genes. Biochar can form part of a solution as it is a well-known adsorbent. This material can be efficient in the adsorption of a wide range of pollutants and is inexpensive. An innovative heat pipe reactor was used to produce biochar from excess food and garden materials. This biochar was characterised using scanning electron microscopy with energy dispersive X-ray analyser (SEM-EDAX), Fourier transform infrared (FTIR) spectroscopy and Raman spectroscopy. The biochar produced had an adsorption capacity between 2.98 mg/g and 8.23 mg/g for initial tetracycline concentrations of 20 mg/l and 100 mg/l, respectively. The Freundlich isotherm provided the best fit to the experimental data. Kinetics examination revealed a rapid adsorption of tetracycline during the initial stages. The Elovich equation fitted the experimental data well. This adsorbent could therefore be produced at the site of an agricultural enterprise through the pyrolysis of agriculture waste and then used to reduce the infiltration of antibiotics into the environment.

Sustainable methods to produce filter materials are needed to remove a variety of pollutants found in water including organic compounds, heavy metals, and other harmful inorganic and biological contaminants. This study focuses on the removal of Cu(II) from copper aqueous solutions using non-activated char derived fromthe pyrolysis of mixed municipal discarded materials (MMDM) using a new heat pipe-based pyrolysis reactor. Adsorption experiments were conducted by adding the char to copper solutions of varying concentration (50-250 mg/L) at a constant temperature of 30 degrees C. The effect of pH on copper adsorption onto the char was also investigated in the range of pH 3 to 6. Copper removal using the char was found to be heavily dependent on pH, adsorption was observed to decrease below a pH of 4.5. However, the initial copper concentration had a little effect on the sorption of copper at high concentration solutions (above 100 mg/L). Overall, the biochar showed an effective copper adsorption capacity (4-5 mg/g) when using copper solutions with a concentration below100 mg/L and pH >4.5. Copper removal using the char tended to follow the pseudo second order kinetic model. Langmuir isothermal model was shown to be the closest fitting isothermusing the linearized Langmuir equation. However, the variety of feedstock used to produce the char led to a variation in results compared to other studies of more specific feedstocks. (c) 2019 The Author(s). Published by Elsevier B.V.

Significant growth of the human population is expected in the future. Hence, the pressure on the already scarce natural water resources is continuously increasing. This work is an overview of membrane and filtration methods for the removal of pollutants such as bacteria, viruses and heavy metals from surface water. Microfiltration/Ultrafiltration (MF/UF) can be highly effective in eliminating bacteria and/or act as pre-treatment before Nanofiltration/Reverse Osmosis (NF/RO) to reduce the possibility of fouling. However, MF/UF membranes are produced through relatively intensive procedures. Moreover, they can be modified with chemical additives to improve their performance. Therefore, MF/UF applicability in less developed countries can be limited. NF shows high removal capability of certain contaminants (e.g. pharmaceutically active compounds and ionic compounds). RO is necessary for desalination purposes in areas where sea water is used for drinking/sanitation. Nevertheless, NF/RO systems require pre-treatment of the influent, increased electrical supply and high level of technical expertise. Thus, they are often a highly costly addition for countries under development. Slow Sand Filtration (SSF) is a simple and easy-to-operate process for the retention of solids, microorganisms and heavy metals; land use is a limiting factor, though. Rapid Sand Filtration (RSF) is an alternative responding to the need for optimized land use. However, it requires prior and post treatment stages to prevent fouling. Especially after coating with metal-based additives, sand filtration can constitute an efficient and sustainable treatment option for developing countries. Granular activated carbon (GAC) adsorbs organic compounds that were not filtered in previous treatment stages. It can be used in conjunction with other methods (e.g. MF and SSF) to face pollution that results from potentially outdated water network (especially in less developed areas) and, hence, produce water of acceptable drinking quality. Future research can focus on the potential of GAC production from alternative sources (e.g. municipal waste). Given the high production/operation/maintenance cost of the NF/RO systems, more cost-effective but equally effective alternatives can be implemented: e.g. (electro)coagulation/flocculation followed by MF/UF, SSF before/after MF/UF, MF/UF before GAC.