Pharmaceuticals enhance our quality of life; consequently, their consumption is growing as a result of the need to treat ageing-related and chronic diseases and changes in the clinical practice. The market revenues also show an historic growth worldwide motivated by the increase on the drug demand. However, this positivism on the market is fogged because the discharge of pharmaceuticals and their metabolites into the environment, including water, also increases due to their inappropriate management, treatment and disposal; now, worldwide, this fact is recognized as an environmental concern and human health risk. Intriguingly, researchers have studied the most effective methods for pharmaceutical removal in wastewater; however, the types of pharmaceuticals investigated in most of these studies do not reflect the most produced and consumed pharmaceuticals on the market. Hence, an attempt was done to analyze the pharmaceutical market, drugs consumption trends and the pharmaceutical research interests worldwide. Notwithstanding, the intensive research work done in different pharmaceutical research fronts such as disposal and fate, environmental impacts and concerns, human health risks, removal, degradation and development of treatment technologies, found that such research is not totally aligned with the market trends and consumption patterns. There are other drivers and interests that promote the pharmaceutical research. Thus, this review is an important contribution to those that are interested not only on the pharmaceutical market and drugs consumption, but also on the links, the drivers and interests that motivate and determine the research work on certain groups of pharmaceuticals on water and wastewater.

Effect of hydrothermal treatment, acid washing and annealing temperature on the structure and morphology of TiO2 nanotubes during the formation process was assessed. X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy analysis were conducted to describe the formation and characterization of the structure and morphology of nanotubes. Hydrothermal treatment of TiO2 precursor nanoparticles and acid washing are fundamental to form and define the nanotubes structure. Hydrothermal treatment causes a change in the crystallinity of the precursor nanoparticles from anatase phase to a monoclinic phase, which characterizes the TiO2 nanosheets structure. The acid washing promotes the formation of high purity nanotubes due to Na+ is exchanged from the titanate structure to the hydrochloric acid (HCl) solution. The annealing temperature affects the dimensions, structure and the morphology of the nanotubes. Annealing temperatures in the range of 400 °C and 600 °C are optimum to maintain a highly stable tubular morphology of nanotubes. Additionally, nanotubes conserve the physicochemical properties of the precursor Degussa P25 nanoparticles. Temperatures greater than 600 °C alter the morphology of nanotubes from tubular to an irregular structure of nanoparticles, which are bigger than those of the precursor material, i.e., the crystallinity turn from anatase phase to rutile phase inducing the collapse of the nanotubes.

Microbial fuel cells (MFCs) are a technology that can be applied to both the wastewater treatment and bioenergy generation. This work discusses the contribution of improvements regarding the configurations, electrode materials, membrane materials, electron transfer mechanisms, and materials cost on the current and future development of MFCs. Analysis of the most recent scientific publications on the field denotes that dual-chamber MFCs configuration offers the greatest potential due to the excellent ability to be adapted to different operating environments. Carbon-based materials show the best performance, biocompatibility of carbon-brush anode favors the formation of the biofilm in a mixed consortium and in wastewater as a substrate resembles the conditions of real scenarios. Carbon-cloth cathode modified with nanotechnology favors the conductive properties of the electrode. Ceramic clay membranes emerge as an interesting low-cost membrane with a proton conductivity of 0.0817 S cm⁻¹, close to that obtained with the Nafion membrane. The use of nanotechnology in the electrodes also enhances electron transfer in MFCs. It increases the active sites at the anode and improves the interface with microorganisms. At the cathode, it favors its catalytic properties and the oxygen reduction reaction. These features together favor MFCs performance through energy production and substrate degradation with values above 2.0 W m⁻² and 90% respectively. All the recent advances in MFCs are gradually contributing to enable technological alternatives that, in addition to wastewater treatment, generate energy in a sustainable manner. It is important to continue the research efforts worldwide to make MFCs an available and affordable technology for industry and society.

Cyclic voltammetry (CV) was used in this work to describe the electrochemical behavior of a dual-chamber microbial fuel cell (MFC). The system performance was evaluated under vacuum and non-pressurized conditions, different reaction times, two sweep potentials, 25 and 50 mVs⁻¹ and under different analyte solutions, such as distilled water and domestic wastewater. CV experiments were conducted by using a potentiostat with three different configurations to collect the measurements. A dual-chamber MFC system was equipped with a DupontTM Nafion^® 117 proton exchange membrane (PEM), graphite electrodes (8.0 cm × 2.5 cm × 0.2 cm) and an external electric circuit with a 100-Ω resistor. An electrolyte (0.1 M HCl, pH ≈ 1.8) was used in the cathode chamber. It was found that the proton exchange membrane plays a major role on the electrochemical behavior of the MFC when CV measurements allow observing the conductivity performance in the MFC in the absence of a reference electrode; under this potentiostat setting, less current density values are obtained on the scanned window potentials. Therefore, potentiostat setting is essential to obtain information in complex electrochemical processes present in biological systems, such as it is the case in the MFCs. Results of the study showed that wastewater constituents and the biomass suspended or attached (biofilm) over the electrode limited the electron charge transfer through the interface electrode-biofilm-liquor. This limitation can be overcome by: (i) Enhancing the conductivity of the liquor, which is a reduction of the ohmic drop, (ii) reducing the activation losses by a better catalysis, and (iii) by limiting the diffusional gradients in the bulk liquor, for instance, by forced convection. The use of the electrolyte (0.1 M HCl, pH ≈ 1.8) and its diffusion from the cathode to the anode chamber reduces the resistance to the flow of ions through the PEM and the flow of electrons through the anodic and cathodic electrolytes. Also reduces the activation losses during the electron transfer from the substrate to the electrode surface due to the electrode catalysis improvement. On the other hand, vacuum also demonstrated that it enhances the electrochemical performance of the dual-chamber MFC due to the fact that higher current densities in the system are favored.

Paracetamol and its toxic transformation products have been found in surface water, wastewater, and drinking water. Effective methods to degrade these products must be found to reduce their detrimental effects on microorganisms in aquatic systems and minimize the concern on human health. Thus, this study looked into the electrochemical oxidation of paracetamol and its oxidation products on surface water, and results were compared with those of paracetamol synthetic solution oxidation. Degradation of paracetamol was conducted using a stainless steel electrode cell, a pH of 3, and direct current densities of 5.7 mA/cm ² (6 V) and 7.6 mA/cm ² (12 V). For both current densities applied, the pharmaceutical and its oxidation products observed by high-performance liquid chromatography with diode-array detection (HPLC-DAD) at 254 nm were totally degraded. Faster degradation of paracetamol was observed at a higher current density. Indeed, 95% of paracetamol was oxidized in only 15 min at the 7.6 mA/cm ² current density. In comparison to the paracetamol synthetic solution's oxidation, degradation of paracetamol was faster in the surface water than the synthetic solution, at 5.7 mA/cm ² . Nevertheless, at 7.6 mA/cm ² , total degradation of paracetamol in surface water was delayed up to 40 min, versus 7.5 min in the synthetic solution. Three oxidation products, observed by HPLC-DAD at 254 nm, were fully oxidized. In comparison with the paracetamol synthetic solution, degradation of the oxidation products in surface water was faster than in synthetic solutions for both current densities. Furthermore, the 7.6 mA/cm ² current density resulted in faster degradation of oxidation products. Results obtained from this work are promising for practical applications because short reaction times and low current densities are needed for degradation of paracetamol and its oxidation products. These densities can be potentially supplied by photovoltaic cells.

Northeastern Mexico is a semiarid region with water scarcity and a strong pressure on water sources caused by the rapid increase of population and industrialization. In this region, rainwater harvesting alone is not enough to meet water supply demands due to the irregular distribution of rainfall in time and space. Thus, in this study the reliability of integrating rainwater harvesting with greywater reuse to reduce water consumption and minimize wastewater generation in the Tecnológico de Monterrey, Monterrey Campus, was assessed. Potable water consumption and greywater generation in main facilities of the campus were determined. Rainwater that can be potentially harvested in roofs and parking areas of the campus was estimated based on a statistical analysis of the rainfall. Based on these data, potential water savings and wastewater minimization were determined. Characterization of rainwater and greywater was carried out to determine the treatment necessities for each water source. Additionally, the capacity of water storage tanks was estimated. For the selected treatment systems, an economic assessment was conducted to determine the viability of the alternatives proposed. Results showed that water consumption can be reduced by 48% and wastewater generation can be minimized by 59%. Implementation of rainwater harvesting and greywater reuse systems in the Monterrey Campus will generate important economic benefits to the institution. Amortization of the investments will be achieved in only six years, where the net present value (NPV) will be on the order of US $50,483.2, the internal rate of return (IRR) of 4.6% and the benefits–investment ratio (B/I) of 1.7. From the seventh year, the project will present an IRR greater than the minimum acceptable rate of return (MARR). In a decade, the IRR will be 14.4%, more than twice the MARR, the NPV of US $290,412.1 and the B/I of 3.1, denoting economic feasibility. Based on these results, it is clear that integrating rainwater harvesting with greywater reuse resulted in a more feasible and reliable strategy than those strategies based only on rainwater harvesting. Furthermore, the investments can be amortized in a shorter period of time.