The use of dynamic membranes as a low-cost alternative for conventional membrane for the treatment of landfill leachate (LFL) was investigated in this study. For this purpose a lab-scale, submerged pre-anoxic and post-aerobic bioreactor configuration was used with nylon mesh as dynamic membrane support. The study was conducted at ambient temperature and LFL was fed to the bioreactor in gradually increasing concentration mixed with tap water (from 20% to 100%). The results of this study demonstrated that lower mesh pore size of 52 μm achieved better results in terms of solid-liquid separation performance (turbidity <10 NTU) of the formed dynamic membrane layer as compared to 200 and 85 μm meshes while treating LFL. Consistently high NH₄⁺-N conversion efficiency of more than 98% was achieved under all nitrogen loading conditions, showing effectiveness of the formed dynamic membrane in retaining slow growing nitrifying species. Total nitrogen removal reached more than 90% however, the denitrification activity showed a fluctuating profile and found to be inhibited by elevated concentrations of free nitrous acid and NO₂⁻-N at low pH values inside the anoxic bioreactor. A detailed metagenomic analysis allowed a taxonomic investigation over time and revealed the potential biochemical pathways involved in NH₄⁺-N conversion. This study led to the identification of a dynamic system in which nitrite concentration is determined by the contribution of NH₄⁺ oxidizers (Nitrosomonas), and by a competition between nitrite oxidizers (Nitrospira and Nitrobacter) and reducers (Thauera).

An integrative passive sampler consisting of a C18 Empore® disk receiving phase saturated with n-octanol and fitted with low-density polyethylene diffusion membrane was calibrated for the measurement of time-weighted average concentrations of hydrophobic micropollutants, including polyaromatic hydrocarbons and organochlorine pesticides, in water. The effect of temperature and water turbulence on kinetic and thermodynamic parameters characterising the exchange of analytes between the sampler and water was studied in a flow-through system under controlled conditions. It was found that the absorption of test analytes from water to the sampler is related to their desorption to water. This allows for the in situ calibration of the uptake of pollutants using offload kinetics of performance reference compounds. The sampling kinetics are dependent on temperature, and for most of the tested analytes also on the flow velocity. Sampler–water partition coefficients did not significantly change with temperature.

In this experimental work, a comparative energy and exergy efficiency study of hemispherical solar still and a single-slope solar still has been carried out. The experiments were conducted in southeast Algeria on 25-5-2020 and 3-6-2020 in the natural climatic environment, and daily accumulation of distilled water produced for both distilleries was measured. The maximum obtained cumulative yield of distilled products is equal to 5.38 kg/m²/day for the hemispherical solar still, and 3.64 kg/m²/day for the single-slope solar still. The overall daily productivity was improved by 47.96% for the hemispherical solar still compared to the single-slope solar still. The maximum daily energy efficiency of the single-slope solar still is 25.81%, and hemispherical solar still is 38.61%. Similarly, the maximum daily exergy efficiency of single-slope solar still is 1.8%, and hemispherical solar still is 3.1%. The main conclusion from the study is the hemispherical distillery greatly enhances productivity as compared to the single-slope distillate and gives more efficiency. Thus, the hemispherical solar still is recommended to be used to provide safe drinking water from salty water.

The performance of spinning basket membrane (SBM) module was tested for the separation of polyvinyl alcohol (PVA) from wastewater. The SBM performance was examined using 50 kDa polyethersulfone ultrafiltration membrane under different parametric conditions. Also, the effects of rotational speed and transmembrane pressure on permeate flux and PVA rejection were investigated. The rotational speed played a significant role in decreasing membrane fouling by reducing the particle deposition on the membrane surface due to enhanced turbulence and shear force. Also, the in-built hydrodynamic cleaning facility of the SBM module allowed easy cleaning of the membrane. The steady-state value of percentage rejection of PVA was above 90% when the steady-state permeate flux value was above 54% of its initial value. The results suggested that spinning basket membrane module was efficient as well as economical for the separation of PVA from aqueous solution.

Elevated concentrations of trace metals in soil can increase the risk of pollution to ecosystems and human health. This cannot be predicted solely from the total and/or extracted concentration of metals from soil samples, as movement of trace elements to the groundwater is also a result of the flow solution through the vadose zone. The rate at which trace elements move are not usually directly measurable, and thus it must be estimated taking into account water transport through the soil. Therefore, a field portable drop-former rainfall simulator has been designed and used to study trace-element mobility in small field plots. The rainfall simulator permits a wide range of variation in rainfall intensities and provides a homogeneous distribution of the simulated rain in a 0.25 m² plot with low cost per data collected and short time. Performance of the rainfall simulator has been evaluated and a preliminary assessment of the amount of pollutants present in the soil (As, Cu and Zn) that can reach groundwater via soil drainage is made by combining rainfall-simulation experiments with infiltration estimates based on a stochastic model of the local climate. The study was conducted in soils affected by the Aznalcóllar toxic spill in the Guadiamar river basin (Spain). Infiltration experiments reveal that the trace elements could be classified according to their mobility as As < Cu < Zn. The presence of high gravel content below this depth increased the amount of drainage and therefore the risk of groundwater pollution, especially with Zn, which was found below 50 cm depth.

In principle, conventional lysimeters are suitable for the investigation of vertical water and solute fluxes. Lateral fluxes in water-saturated fen sites are characterized by heterogeneities and abnormities due to anisotropic layering. But due to lack of adequate monitoring techniques, these fluxes have been insufficiently analyzed. The newly developed large weighable fen lysimeter (LWFL) overcomes the limitations of conventional lysimetry and enables the measurement of vertical and horizontal transport processes in undisturbed large volume soil monoliths. The LWFL has a volume of 6 m³ (4 m length, 1 m width and 1.5 m depth) and was tested by filling the lysimeter with an undisturbed fen monolith. A special extraction procedure for the horizontal sliding of the lysimeter vessel through the natural fen was developed. In front of the vessel a converted cutting tool assisted in carving the soil monolith out of the peat, both vertically and horizontally. Inlet and outlet of the LWFL was constructed to allow the adjustment of a wide range of hydraulic gradients to depict natural occurring lateral transport processes. The LWFL including the measurement techniques was tested successfully for 3 years. On the basis of these tests, we conclude that complex physical and biogeochemical research problems involving lateral flows can be tackled now with multiphase observations and measurements at high spatial and temporal resolution, transdisciplinary data evaluation and numerical modelling approaches.

The present study aims to investigate the optimum condition of stationary diesel engine’s operating parameters to obtain better performance and emission level, where the diesel engine is fueled with different concentrations of soybean biodiesel (SB), water, and alumina (Al) nanoadditive. Taguchi method coupled with gray relational analysis has been implemented in this study to obtain the optimum concentration of SB, water, and Al nanoparticle, and statistical analysis of variance (ANOVA) is applied to obtain the individual response of operating parameters on overall engine performance and emission level. Various concentration of SB (10%, 20%, and 30%), water (10%, 20%, and 30%), and Al nanoparticle (50 ppm, 100 ppm, and 150 ppm) are mixed with base diesel (BD) by mechanical agitation and followed by an ultra-sonication process. The fuel properties are measured based on EN590 standards, and the experiments are conducted in a single-cylinder, four-stroke, natural aspirated stationary diesel engine based on an L₉ orthogonal array fuel combination. From the obtained gray relational co-efficient (GRC) and signal-to-noise (S/N) ratio, the optimum concentration of SB, water, and nanoadditive are identified as 20%, 10%, and 100 ppm, respectively, and a confirmation experiment has also been carried out to confirm the improvements at optimum condition. The ANOVA results imply that water concentration (WC) has the maximum influence on overall diesel engine’s performance and emission level followed by nanoparticle and SB concentrations. Overall, it can be concluded that the engine exhibits better performance and greener emissions at optimal condition.

The effect of aeration rate on nutrient removal from slaughterhouse wastewater was examined in two 10-L laboratory-scale sequencing batch reactors (SBRs--SBR1 and SBR2) operated at ambient temperature. The contaminants in the slaughterhouse wastewater had average concentrations of 4,000 mg chemical oxygen demand (COD) L⁻¹, 350 mg total nitrogen (TN) L⁻¹ and 26 mg total phosphorus (TP) L⁻¹. The duration of a complete SBR operation cycle was 8 h and comprised four operational phases: fill (7 min), react (393 min), settle (30 min) and draw/idle (50 min). During the react phase, the reactors were intermittently aerated four times at 50-min intervals, 50 min each time. DO, pH and oxidation-reduction potential (ORP) in the reactors were real-time monitored. Four aeration rates--0.2 L air min⁻¹ in SBR1 for 70 days, 0.4 L air min⁻¹ in SBR1 for 50 days, 0.8 L air min⁻¹ in SBR2 for 120 days and 1.2 L air min⁻¹ in SBR1 for 110 days--were tested. When the aeration rate was 0.2 L air min⁻¹, the SBR was continuously anaerobic. When the aeration rate was 0.4 L air min⁻¹, COD and TP removals were 90% but TN removal was only 34%. When the aeration rates were 0.8 and 1.2 L air min⁻¹, average effluent concentrations were 115 mg COD L⁻¹, 19 mg TN L⁻¹ and 0.7 mg TP L⁻¹, giving COD, TN and TP removals of 97%, 95% and 97%, respectively. It was found that partial nitrification followed by denitrification occurred in the intermittently aerated SBR systems.