When discharged into wastewater, pharmaceuticals and personal care products (PPCPs) become microorganic contaminants and are among the largest groups of emerging pollutants. Human, animal, and aquatic organisms’ exposures to PPCPs have linked them to an array of carcinogenic, mutagenic, and reproductive toxicity risks. For this reason, various methods are being implemented to remove them from water bodies. This report critically reviews these methods and suggests improvements to removal strategies. Biological, physical, and chemical methods such as biological degradation, adsorption, membrane filtration, and advanced electrical and chemical oxidation are the common methods used. However, these processes were not integrated into most studies to take advantage of the different mechanisms specific to each process and are synergistic in the removal of the PPCPs that differ in their physical and chemical characteristics (charge, molecular weight, hydrophobicity, hydrogen bonding, structure). In the review articles published to date, very little information is available on the use of such integrated methods for removing PPCPs. This report attempts to fill this gap with our knowledge.

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Clean water shortage is a major global problem due to escalating demand resulting from increasing human population growth and industrial activities, decreasing freshwater resources and persistent droughts. Recycling and reuse of wastewater by adopting efficient reclamation techniques can help solve this problem. However, wastewater contains a wide range of pollutants, which require removal before it may be reused. Adsorption and membrane processes are two successful treatments used to remove most of these pollutants. Their efficiency increases when these processes are integrated as observed, for example in a submerged membrane adsorption hybrid system (SMAHS). It uses coarse air bubbling/sparging to produce local shear which minimises reversible membrane fouling, improves performance and extends the life of the membrane. Additionally, the adsorbent acts as a buoyant media that produces an extra shearing effect on the membrane surface, reduces membrane resistance and increases flux. In addition, it adsorbs the organics that would otherwise deposit on and cause fouling of the membrane. The use of activated carbon (AC) adsorbent in SMAHS is very effective in removing most pollutants including natural organic matter (NOM) and organic micropollutants (OMPs) from wastewaters and membrane concentrate wastes, the latter being a serious problem in practical applications of the reverse osmosis process. However, certain NOM fractions and OMPs (i.e. hydrophilic and negatively charged ones) are not efficiently removed by AC. Other adsorbents need to be explored for their effective removal. Graphical abstract

Reverse osmosis concentrate (ROC) produced as the by-product of the reverse osmosis process consists of a high load of organics (macro and micro) that potentially cause eco-toxicological effects in the environment. Previous studies focused on the removal of such compounds using oxidation, adsorption, and membrane-based treatments. However, these methods were not always efficient and formed toxic by-products. The impact of ion-exchange resin (IEX) (Purolite®A502PS) was studied in a micro-filtration–IEX hybrid system to remove organics from ROC for varying doses of Purolite® A502PS (5–20 g/L) at a flux of 36 L/m2h. The purolite particles in the membrane reactor reduced membrane fouling, evidenced by the reduction of transmembrane pressure (TMP), by pre-adsorbing the organics, and by mechanically scouring the membrane. The dissolved organic carbon was reduced by 45–60%, out of which 48–81% of the hydrophilics were removed followed by the hydrophobics and low molecular weight compounds (LMWs). This was based on fluorescence excitation-emission matrix and liquid chromatography-organic carbon detection. Negatively charged and hydrophobic organic compounds were preferentially removed by resin. Long-term experiments with different daily replacements of resin are suggested to minimize the resin requirements and energy consumption.

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