Disposing of nitrate-containing effluents from seawater-fed intensive aquacultural applications is a major environmental problem. A possible solution is to mix nitrate-rich effluents from marine recirculating aquaculture systems (RASs) with citrate-rich liquid wastes (CLW), a common by-product of the food industry. Where possible, such strategy can alleviate two environmental problems simultaneously, in a cost-effective fashion. However, concerns are often raised regarding secondary pollution stemming from the use of CLW, particularly related to phosphorus and heavy metals. This work showed that both phosphorus and heavy metal were completely absorbed by the bacterial sludge generated in the process, indicating low environmental risk associated with the disposal of the treated effluent to the environment. Operation of continuous stirred-tank reactor (CSTR) single-sludge denitrification reactor with CLW as electron and carbon donor resulted in high nitrate removal efficiency (>95 %) and denitrification rate of up to 1.6 g NO₃-N L⁻¹reactor day⁻¹along with low bacterial biomass yield [0.23 g chemical oxygen demand (COD) new cells g⁻¹COD citrate]. Moreover, the use of CLW was found to be environmentally safe and equally efficient to the use of traditional, costly carbon sources such as methanol and acetic acid, rendering this alternative attractive for treatment of nitrate-rich saline effluents.

Removal of micropollutants from water with NF/RO membranes has received much attention in recent years. However, because of especially diffusion through the polyamide layer, NF/RO membranes never achieve complete removal, which may be a problem given the possibility of micropollutants causing adverse effects in even very low concentrations. In this paper, we have investigated a strategy of implementing adsorbents into the support layer of a NF membrane to increase the overall removal of three selected pesticides by combining membrane rejection and adsorption into one unit operation. The objective of the study was to act as proof of concept for the scheme, as well as to gain insights into how adsorbents may be inserted into the membrane support, and how they affect the membrane performance. The results showed that the addition of the adsorbents to the membrane increased the adsorption capacity of the membrane, and that the adsorbents could be embedded in the membrane without affecting the flux and rejection behaviour. This however depended very much on the specific manufacturing method. Furthermore, the adsorption capacity was found to vary significantly for the three pesticides, indicating a need for adsorbents designed to specifically target a given micropollutant. Overall, the concept of a complete removal membrane is realisable, but several challenges remain to be solved.

In this study, we developed a new method for the preconcentration and spectrophotometric determination of vanadium (V) using dispersive liquid-liquid microextraction (DLLME) and optical sensors using 4-(5-bromo-2-pyridylazo)-5-(diethylamino)-phenol (Br-PADAP) as a complexing reagent. The preconcentration is based on the extraction of vanadium ions (V) in trichloroethylene in the form of a complex with Br-PADAP, using ethanol as a dispersion solvent. After injecting the solvent into a solution containing vanadium, a homogeneous mixture is obtained. The mixture is centrifuged to deposit the desired phase onto a triacetylcellulose membrane. Then, the supernatant is discarded, and the membrane is exposed to the radiation beam of a spectrophotometer without the use of a microcuvette. Under optimal conditions, the detection limit was determined to be 0.57 μg L⁻¹, and the quantification limit was 1.91 μg L⁻¹. The accuracy of the method was verified by analyzing a certified reference material, BCR®414, plankton. The procedure was applied to the determination of vanadium levels in shellfish samples, specifically shrimp and oyster.

This study investigated and characterised organic matter present in sediment particles deposited in infiltration facilities using an excitation-emission matrix method combined with parallel factor analysis (EEM-PARAFAC). The organic fluorophore identified was correlated with sediment bound metals. The PARAFAC analysis identified three major components. The fluorophore in each of the three components appeared in different locations with different spectral shapes. The maximum fluorescence intensity (F ₘₐₓ) observed for each fluorescent component was correlated with seven heavy metals (Cr, Mn, Co, Ni, Cu, Zn and Pb). F ₘₐₓ of component 1 displayed a negative relationship with all the metals (correlation coefficient = −0.28 to −0.72), and F ₘₐₓ of component 3 showed a positive relationship (0.20 to 0.62), and among them, Cu, Ni and Zn had higher correlation. Our results demonstrate that a PARAFAC approach can help to further elucidate organic matter species, thereby allowing a better understanding of the mobility of elemental species in the deposited sediment.

Uranium soil depollution is of great concern as, like any other radionuclide, it may accumulate in time and generate a negative impact on human health. There are several decontamination technologies, among these the acid washing still in use for its simplicity and low cost. Though a classical method, it still can be improved by using the best operating conditions to increase the decontamination degree. The present study aims to propose an optimization approach based on experimental design. The investigation takes into account the main operating parameters (duration, temperature, and pH) and the soil characteristics (texture and organic matter content). This work presents an “ex situ” uranium-contaminated soil treatment using a 0.1 M H₂SO₄solution with pulp density of 0.5. The experiments followed a 2³factorial design for the evaluation of factors and interaction effects. The factors’ influence differed from one type of soil to another. The 2³experiment was augmented using a non-central composite design that allowed the formulation of a second degree model for the response surface. The best values for the operating parameters were identified using optimization procedures. Statistical modelling and optimization were performed in Matlab® v7.7. The results obtained proved that the soil type is very important for selecting better operating conditions. These improvements determined an increased decontamination degree of up to 10–13 % compared with standard operating conditions that were considered as central point in the experimental plan.

Aquatic plant biomass has been shown to have a great potential for biogas production. The use of ruminal fluid has been shown to improve the degradation of the lignocellulosic material with its conversion into volatile fatty acids (VFA) during a first phase of hydrolysis–acidogenesis. VFAs are important as the feedstock for methane and hydrogen production in a second phase process within a biorefinery. The objective of this work was to produce a high yield of VFA during a first phase of anaerobic hydrolysis–acidogenesis of Pistia stratiotes biomass assessing the effect of the use of rumen fluid as inoculum and of daily adjustment of pH in batch-operated reactors. One liter anaerobic reactors containing 15 gSV L⁻¹ of P. stratiotes biomass were incubated at 30 ± 2 °C and agitated once a day. The inoculum concentration had no significant effect on the increase in VFA concentration and 20 % (V/V) was used in all treatments. The final average VFA concentration and conversion coefficients from VS to VFA in the inoculated treatment with no pH adjustment (T1) and with pH adjustment (T2) (1817 mgCOD L⁻¹ and 0.1319 mgVFA mgVS⁻¹, respectively) were significantly higher than those found in the treatment with no inoculum (T0). There were no significant differences between T0 and T1 in the VS degradation rate. In contrast, the degradation rate in T2 was significantly higher. Thus, the addition of ruminal fluid promoted the production of VFA, and the pH adjustment had no significant effect on this parameter but did influence the biomass degradation.

The adsorbents (such as hydrous ferric oxides, HFO) generated in the electrocoagulation (EC) processing with iron electrodes are able to remove effectively inorganic arsenic (As) present in underground water. A characterization of the HFO phases produced during the arsenic removal by the EC process from low and high arsenic concentration, by using X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, energy dispersive X-ray spectroscopy (EDS) and scanning electron microscopy (SEM), is presented. The main HFO phase produced by this process is lepidocrocite (γ-FeOOH), and that the sorption of arsenic by this solid-state phase formed as part of the EC process was effective in removing arsenic from aqueous solution.

From a storm water management perspective, not all pavements are equivalent. Pavement type can impose a strong influence on pollutant wash-off dynamics. Pollutant loads from pavement wash-off are affected by the pavements’ physical and chemical composition. However, there is a dearth of information regarding how pavement type influences atmospherically deposited pollutant loads in storm water. Therefore, experimental impermeable and permeable asphalt and concrete boards were deployed in a residential area in Christchurch, New Zealand, to quantify the influence of pavement type on storm water pollutant dynamics. Each pavement type had four replicate systems elevated 500 mm from the ground at a 4° slope. Wash-off from the pavements was collected and analysed for total suspended solids and metals (Cu, Pb, and Zn) from June to August 2014. Results show that Cu and Zn loads were lower from the concrete pavements than the asphalt pavements because the carbonates and hydroxides within the concrete adsorbed Cu and Zn. Run-off from the impermeable asphalt had the highest loads of Zn, which was attributed to Zn leaching from the asphalt. Infiltrate from permeable asphalt provided little/no retention of Cu and Zn, due to the low pH of the infiltrate causing Cu and Zn to partition into the dissolved phase and leach through the pavement. Total suspended solid (TSS) and Pb loads were the highest in run-off from the impermeable concrete, which was attributed to the smooth surface enabling particulates to be easily mobilised. TSS and Pb loads were the lowest from the permeable pavement due to the permeable material filtering out particulates.

2,3-Dihydroxybenzaldehyde modified silica gel (SGDHB) was prepared and then used for the removal of boron. Adsorption of boron on the SGDHB was examined with respect to the equilibrium adsorption, kinetics and as a function of pH. Boron is strongly retained on the SGDHB between pH 7 and pH 9. The results indicated that the adsorption equilibrium was well described by the Langmuir equation. The SGDHB exhibited an excellent sorption capacity with 3.812 mmol B/g SGDHB under experimental conditions. The material shows reasonably rapid sorption ability, with boron in 25 mL of 0.01 M H₃BO₃ solution being removed almost completely within 30 min of contact time with 0.12 g of the modified silica gel. The SGDHB was demonstrated to be an efficient sorbent for the removal of boron.