Except for the specific surface area and pore size, the hydroxyl groups on the surface of the ferric oxides were determined as the key factor in arsenic adsorption in this study. Two synthetic mesoporous ferric oxides, amorphous ferric oxyhydroxide (AFO) and goethite, were used to adsorb As(III) and As(V) in aqueous solution. The experimental results showed that the AFO had a higher hydroxyl group density, resulting in a higher arsenic adsorption capacity than that on the goethite for both As(III) and As(V). Also, it was found that the adsorption of As(III) on both the goethite and AFO was faster than that of As(V), and the adsorption rate fitted the pseudo-second-order kinetics. The findings indicated a promising modification of adsorbents for arsenic remediation.

The adsorption of copper (Cu(II)) from aqueous solutions by activated Luffa cylindrica biochar fibres has been investigated by means of batch equilibrium experiments and FTIR spectroscopy. The effect of various physicochemical parameters, such as pH, initial metal concentration, ionic strength, mass of the adsorbent, contact time and temperature, has been evaluated by means of batch type adsorption experiments. FTIR spectroscopy, as well as acid-base titrations, was used for the characterization of the material and the surface species formed. According to the experimental results even at pH 3, the relative sorption is above 85% and the adsorption capacity of the activated biochar fibres for Cu(II) is q ₘₐₓ = 248 g kg⁻¹. Moreover, the interaction between the surface carboxylic moieties and Cu(II) results in the formation of very stable inner-sphere complexes (∆G ᵒ = −11.2 kJ mol⁻¹ at pH 3 and −22.4 kJ mol⁻¹ at pH 5.5).

Antibiotics are often misused or overused, resulting in large residue inputs in the environment. Electricity and antibiotics were regarded as potentially important factors, which impact on the microbial community during treatment of antibiotics in three-dimensional biofilm-electrode reactors (3D-BERs). Unfortunately, only a few studies have been reported yet. Four 3D-BERs and one 3D-BR (reactor with biological sludge and no voltage) were designed to assess the effect of low current, sulfamethoxazole (SMX), and tetracycline (TC) on microbial populations. The 3D-BERs achieved excellent removal efficiencies of 72.20–93.52 and 82.61–95.80% for SMX and TC, respectively. Microorganisms were classified into 58 phyla, 125 classes, 166 orders, 187 families, and 220 genera. Proteobacteria held the overwhelming predominance, followed by Bacteroidetes, Chloroflexi, Actinobacteria, Verrucomicrobia, Firmicutes, and Acidobacteria. The 3D-BERs achieved higher richness of microbial composition compared with the 3D-BR. Microbial communities and relative abundance at the phyla level were affected by low current. The microbial communities in the 3D-BERs were similar at the genus level, even with different antibiotic concentrations. However, the relative abundances and compositions of the microbial communities decreased during the treatment of antibiotics. To increase the performance of 3D-BERs, the function of microorganisms should be investigated in future studies.

Aeration of the biological reactor in wastewater treatment plants (WWTPs) represents one of the major cost items, which may account for more than 50% of the total energy consumption. Therefore, airflow rate must be supplied based on the real needs of the biological reactions and the goals to be achieved in terms of removal efficiency and effluent quality. Among the different strategies available to optimize energy consumption of air supply, the Oxy Fuzzy logic and oxidation reduction potential (ORP)-based control systems have proven to be efficient and reliable. The present study compares the effects of these two control systems in terms of energy consumption and efficiency of COD and ammonia oxidation in the activated sludge reactors of two WWTPs for domestic sewage. Both systems allowed to largely comply with the limits set on the effluent for COD and ammonia in spite of the dynamic pattern of the influent load. The Oxy Fuzzy system led to reducing energy consumption by 13% while the ORP control system only by 2%, as average per year. The Oxy Fuzzy system showed higher flexibility, being more capable of adapting the set-points in relation to the influent load. The ORP system seemed to be more suitable for plants where the influent load does not change significantly: the set-points are fixed and the input load can be properly managed only for limited variations.

In this study, activated red mud was used to develop an effective adsorbent in order to remove a toxic azo dye (tartrazine E102) from aqueous solutions. To increase the adsorption capacity, the red mud was activated by acid-heat treatment using 20 wt.% HCl (RM-HCl). To establish the optimum operating parameters, the influence of pH, adsorbent dose, contact time, initial dye concentration, and stirring rate was investigated. The adsorption equilibrium was studied using Langmuir, Freundlich, Dubinin-Radushkevich, Temkin isotherm models, and the characteristic parameters for each adsorption isotherm were determined. The kinetics of the adsorption process was analyzed by means of pseudo-first-order and pseudo-second-order models. The maximum removal efficiency obtained under optimum conditions was 84.72%. These results were in accordance with the isotherm and kinetic data. The results suggested that tartrazine adsorption process follows the pseudo-second-order kinetic model and also that fits Langmuir isotherm model. The maximum monolayer adsorption capacity was 136.98 mg/g.

This paper explores the proposition that we are living in an era marked by unprecedented quantities and exotic types of human waste and environmental contamination by examining the impact of anthropogenic activity on the Earth’s epiderm. Specifically, the paper introduces anthrosols and technosols as critical markers of unfettered human activity as recorded in the terrestrial stratigraphic signature of soils and sediments adversely impacted by municipal, agricultural, industrial and maritime activities. The paper presents examples of the sources and fates of some of the most worrisome contaminants, many of them persistent organic pollutants, including common heavy metals-metalloids and hydrocarbons but also instances of more unfamiliar drug residues and antibiotic resistant genes, at Australia’s 160,000 contaminated sites.Consideration is given to how anthropogenic elements and compounds in soil may bioaccumulate and bioconcentrate in animals, and how they can subsequently be consumed to the detriment of human health. Among the 75,000 identified contaminants in Australian soils are tributyltin, which has a half-life of at least 10 years and is one of the most toxic chemicals introduced into the environment by man, and uranium-contaminated mine tailings, which require constant and careful management for up to 75,000 years if their polluting effects are to be minimized. The author concludes that anthrosols and technosols provide evidence of the Anthropocene in Australia.

Hexavalent chromium (Cr(VI)) in wastewater is a great risk to the quality of water sources and to human health. Meanwhile, Chinese herb-extraction residues (CHER) are the by-products from the extraction process of Chinese medicine. This study investigated the use of CHER to adsorb Cr(VI) from aqueous solution. Results indicated that adsorption was maximum at solution pH of 2.0 while the Cr(VI) removal efficiencies for chuanxiong rhizome residue (CRR) and Chinese wolfberry residue (CWR) were 86.56 and 99.93%, respectively. Isotherm data were modeled by using Freundlich, Langmuir, and Temkin isotherms. The maximum monolayer adsorption capacities for CWR and CRR were 79.60 and 36.21 mg g⁻¹, while their corresponding adsorption capacities obtained from experimental data were 37.30 and 32.42 mg g⁻¹, respectively. However, Freundlich isotherm fitted the data well. Both adsorption and reduction of Cr(VI) to Cr (III) forms followed by complexation onto the adsorbent surfaces favored removing Cr(VI). The results also suggested that the abundant and cheaply available CRR and CWR can be used as efficient adsorbent materials for Cr(VI) removal from wastewater.

According to our previous results on the magnesium-based exhaust gas cleaning system (Mg-EGCS), certain parameters of the desulphurization wastewater (such as chemical oxygen demand (COD), suspended solids (SS), total oil content and turbidity) were above the washwater discharge criteria set by the International Maritime Organization (IMO). In this work, a novel combined process of aeration-centrifugation and filter pressing was proposed, and a pilot-scale experiment was carried out to treat the desulphurization wastewater. The results demonstrated that the quality of wastewater treated by the combined process could meet the IMO’s washwater discharge standard, with COD of 115 mg/L, SS of <5 mg/L, polycyclic aromatic hydrocarbons (PAHs) of <1 μg/L, and total oil content of 5.1 mg/L, when the washwater flow rate was 0.45 m³/h.

Mercury (Hg) speciation and bioavailability were studied in surface water, surface sediment and freshwater fish samples collected upstream and downstream of the Medupi (currently under construction) and Matimba power stations in the Waterberg area, Limpopo Province. The initial survey was conducted in May 2010 and continued periodically/seasonally until October 2014. This study was designed to provide an overall description of the levels of Hg in areas potentially impacted by emissions from the coal-fired power station and provide the necessary information to enhance the understanding of the factors regulating the fate and transport of Hg in the environment. Percent loss on ignition (LOI) and ancillary water quality measurements were also carried out. In this study, the total mercury (TotHg) concentrations ranged between 0.92 and 29.13 ng/L, and 0.13 and 8.00 ng/L for methylmercury (MeHg) in water. Total Hg concentrations ranged between 0.50 and 28.60 ng/g, while the MeHg concentration ranged between 0.08 and 2.22 ng/g in sediments. Mercury concentrations in fish ranged between 40 and 1200 ng/g for TotHg, and 13.42 and 600 ng/g for MeHg. Methylmercury concentrations in freshwater fish sampled exceeded the United States Environmental Protection Agency criteria (300 ng/g) in 10% of the total fish sampled and 5% exceeded the WHO guideline (500 ng/g).

Although there is a growing interest in emerging organic contaminants (EOCs), most research is focused on wastewater treatment, the occurrence of EOCs, and their fate in the aquatic environment. There is limited information about their behavior in agricultural soils, where they can be introduced via irrigation with treated wastewater (TWW). In this study, the degradation in an agricultural soil of eight EOCs (bisphenol A, carbamazepine, diethyl phthalate, ethyl paraben, 5-methyl-1H-benzotriazole, primidone, Surfynol 104, and tris(2-chloroethyl) phosphate) with a broad range of physical-chemical properties was monitored for 40 days. Two types of soil treatments were performed: non-sterilization and sterilization. In the non-sterilized soil, by the end of the incubation period, degradation was greater than 70% for all the target compounds except carbamazepine, Surfynol 104, and primidone (<50%). In contrast, in the sterilized soil, the degradation of most of the compounds was less than 50%, except ethyl paraben, 5-methyl-1H-benzotriazole, and diethyl phthalate (>70%). These findings indicate that soil sterilization reduces overall degradation rates, which suggests that microbial activity plays an important role in the degradation of most of the EOCs studied in soil.