Nitrogen is a main contaminant of wastewater worldwide. Novel processes for nitrogen removal have been developed over the last several decades. One of these is the partial nitritation process. This process includes the oxidation of ammonium to nitrite without the generation of nitrate. The partial nitritation process has several advantages over traditional nitrification-denitrification processes for nitrogen removal from wastewaters. In addition, partial nitritation is required for anammox elimination of nitrogen from wastewater. Partial nitritation is affected by operational conditions and substances present in the influent, such as quinolone antibiotics. In this review, the impact that several operational conditions, such as temperature, pH, dissolved oxygen concentration, hydraulic retention time and solids retention time, have over the partial nitritation process is covered. The effect of quinolone antibiotics and other emerging contaminants are discussed. Finally, future perspectives for the partial nitritation process are commented upon.

This study reports the adsorption capacity of lead Pb²⁺ and cadmium Cd²⁺ of biochar obtained from: peanut shell (BCM), “chonta” pulp (BCH) and corn cob (BZM) calcined at 500, 600 and 700 °C, respectively. The optimal adsorbent dose, pH, maximum adsorption capacity and adsorption kinetics were evaluated. The biochar with the highest Pb²⁺ and Cd²⁺ removal capacity is obtained from the peanut shell (BCM) calcined at 565 °C in 45 min. The optimal experimental conditions were: 14 g L⁻¹ (dose of sorbent) and pH between 5 and 7. The sorption experimental data were best fitted to the Freundlich isotherm model. High removal rates were obtained: 95.96% for Pb²⁺ and 99.05. for Cd²⁺. The BCH and BZM revealed lower efficiency of Pb²⁺ and Cd²⁺ removal than BCM biochar. The results suggest that biochar may be useful for the removal of heavy metals (Pb²⁺ and Cd²⁺) from drinking water.

Biological wastewater treatment (WWT) frequently relies on biofilms for the removal of anthropogenic contaminants. The use of inert carrier materials to support biofilm development is often required, although under certain operating conditions microorganisms yield structures called granules, dense aggregates of self-immobilized cells with the characteristics of biofilms maintained in suspension. Molecular techniques have been successfully applied in recent years to identify the prokaryotic communities inhabiting biofilms in WWT plants. Although methanogenic Archaea are widely acknowledged as key players for the degradation of organic matter in anaerobic bioreactors, other biotechnological functions fulfilled by Archaea are less explored, and research on their significance and potential for WWT is largely needed. In addition, the occurrence of biofilms in WWT plants can sometimes be a source of operational problems. This is the case for membrane bioreactors (MBR), an advanced technology that combines conventional biological treatment with membrane filtration, which is strongly limited by biofouling, defined as the undesirable accumulation of microbial biofilms and other materials on membrane surfaces. The prevalence and spatial distribution of archaeal communities in biofilm-based WWT as well as their role in biofouling are reviewed here, in order to illustrate the significance of this prokaryotic cellular lineage in engineered environments devoted to WWT.

Reverse osmosis is currently the most important and commonly used desalination technique. The objective of this paper is to review the history of reverse osmosis membranes, to outline the current state of the art and insight into the tendencies being. The current market of RO membranes is focused on thin-film composite polyamide membranes, which are made of three layers and with an average molecular weight cut-off of 100–150 Da in order to obtain a high salt rejection. Until reaching current RO membranes, there have been numerous developments, highlighting the development of NS-100 membranes by Cadotte in 1977 and subsequent optimization of the manufacturing conditions. Other improvements were surface modification and membrane post-treatment actions. The most common configuration used in desalination plants are polyamide spiral wound membranes (SWM), which involves several flat sheet membranes that are glued together pairwise on three sides with the fourth side left open. The membrane elements are connected in series using interconnectors and installed into a pressure vessel. Current research regarding SWM is focused on providing greater surface area within the same volume. Another point of interest is to achieve a high retention of boron to comply with current legislation.

Drinking water requires excellent physico-chemical quality. It must therefore not contain any substance which is harmful, or which may harm the health of the consumer. The drinking water supply of Bangeli canton (Togo) is provided by ground water and surface water which have been polluted by several industrial discharges as a result of Togo’s intensive industrialization in the last few decades. In order to contribute to the control of drinking water in this locality, our study focused on the state of metal pollution in the waters of this canton. To assess the spatiotemporal evolution of the metallic contamination in Bangeli waters, surface and groundwater samples were taken during dry and rainy seasons in the last three years. This comparative study will allow for a more in-depth assessment of the study area. These samples were analysed by ICP-MS for heavy metals such as Fe, Pb, Cr, Zn, Cu, Co, As, Mn, Sb, Ni, and Cd. The mean values obtained for these metals from groundwater are, respectively, 1144.87; 2.53; 3.42; 3.63; 6.49; 0.69; 143.76; 160.03; 5.67; and 0.036 µg/L. Except for Fe, Sb, and Mn, all the other metals have values below WHO guidelines. The heavy metal pollution index (HPI) applied to these waters gave values between 31.49 and 307.51, with 88.66% of samples below the limit value (100). Health risk assessment factors, including average daily doses, hazard quotient, carcinogenic risks, and hazard index indices, were computed for children and adults. Finally, the HPI index of Fe and Sb in both child and adult cases showed a value greater than the safe limits, which causes harmful health hazards and potential non-carcinogenic health risks to humans. However, carcinogenic risk for Cr, Cd, Pb, and As is less than the limit value (10⁻⁴), indicating that there is no risk of cancer. The interpretation of PCA results made it possible to understand that mining has contributed to the pollution of some water resources in Bangeli, and cluster analysis (CA) applied to the data showed that the sampling points can be grouped into four groups, which were primarily formed by extravagant concentrations of Fe, Mn, Cu, and Sr.