Investigation of mechanisms of an upflow-downflow siliceous sand filtration system for surfactants bathroom grey water treatment.

Sustainable decentralized wastewater treatment systems (DEWATS) at the local level are considered as a smart alternative for small communities particularly in arid areas. The present study examines the mechanisms of an upflow-downflow Siliceous Sand (SS) filtration system involved in surfactants bathroom grey water treatment. In order to get a better understanding of the mechanisms involved in surfactants removal, particle size distribution and Fourier transform infrared (FTIR) spectroscopy of the SS particles were performed. Optimization of the upflow-downflow SS filtration system, operated following operational conditions of hydraulic load rate (HLR) and SS amounts, results indicates an average removal efficiency (ARE) of 93.7% reached with respect to surfactants removal. Results showed also that the resulting silicate materials react with surfactants in a cooperative assembly process involving the interaction of SS particles with surfactants aggregates. Brunauer, Emmett and Teller (BET) surface area, pore volume (Vp), and pore size were found to be significantly reduced post-filtration with respectively 3.39%, 24.31%, and 21.86% reduction. From FTIR spectroscopy analysis of the Sulfonates, Silanol and Silane functional groups appear to be involved in mesoporous constructed micelle organization for surfactants removal. Such geo-materials could be green and sustainable for various applications in water and environmental engineering.

Assessment of the application of cladode cactus mucilage flocculants for hot chemical degreasing electroplating wastewater treatment and reuse: process efficiency and storage stability.

Pressures related to urban growth and industrial activities exacerbated by climate change had an impact on water resources in Tunisia. The present study examines the application of cladode cactus mucilage (CCM) flocculants for hot alkaline chemical degreasing Zn-electroplating wastewater treatment and reuse (WWTR). The CCM flocculation process was selected through their environmental benefits, economic facilities, sustainable use of the natural biopolymer product, input biopolymers substitution, and on-site treated wastewater (TWW) reuse and recovery. The alum coagulation and CCM flocculation were performed by the jar test series. The suitability of treated wastewater quality (TWWQ) with alum/CCM was also assessed for reuse purpose in terms of corrosion-scaling indices (RSI, LSI, PSI, AI), oxidation-reduction potential (ORP), and microbiological community growth (Bacillus, Pseudomonas, Mesophilic bacteria and yeasts) for 28 days storage at 25 °C. The total alkalinity removal efficiency reached 95.8% with an optimum dosage of alum + CCM for hot alkaline chemical degreasing wastewater bath rinsing. The results showed that the stability of TWWQ has significantly deteriorated during storage leading to aggressive wastewater, pathogen growth, and biological malodor production which make them unsuitable for reuse. Therefore, there is a need for CCM processing alternatives that preserve the physico-chemical and microbial of TWW properties during storage.

Removal of pentachlorophenol from contaminated wastewater using phytoremediation and bioaugmentation processes.

The phytoremediation procedure was conducted by Lemna gibba (L) and Typha angustifolia (T) and the bioaugmentation procedure used P. putida HM627618. The ability of the selected P. putida HM627618 to tolerate and remove PCP (200 mg L-1) was measured by high performance liquid chromatography analysis and optical density at 600 nm. Five different experiments were conducted in secondary treated wastewater for PCP testing removal (100 mg L-1) including two phytoremediation assays (T + PCP; L + PCP), three bioaugmentation-phytoremediation assays (T + B + PCP; L + B + PCP; L + T + B + PCP) and a negative control assay with PCP. Various analytical parameters were determined in this study such as bacterial count, chlorophylls a and b, COD, pH and PCP content. The main results showed that the average PCP removal by P. putida HM627618 was around 87.5% after 7 days of incubation, and 88% of PCP removal was achieved by treatment (T + B) after 9 days. During these experiments, pH, COD and chloride content showed a net increase in all treatments. The chlorophylls a and b in case of (T) and (L) Chlorophylls a and b for T and L phytoremediation showed a decrease with a value less than 10 µg/mg of fresh material after 20 days of cultivation.

Suitability assessment of grey water quality treated with an upflow-downflow siliceous sand/marble waste filtration system for agricultural and industrial purposes.

The present study examines the suitability assessment of an upflow-downflow siliceous sand/marble waste filtration system for treatment and reuse of grey water collected from bathrooms of the student residential complex at the Higher Institute of Engineering Medjez El Bab (Tunisia). Once the optimization of grey water pre-treatment system has been determined, the filtration system was operated at different hydraulic loading rate and media filter proportions in order to assess the suitability of treated grey water for irrigational purpose according to salinity hazard, sodium hazard, magnesium hazard, permeability index, water infiltration rate, and widely used graphical methods. Suitability of the treated grey water for industrial purpose was evaluated in terms of foaming, corrosion, and scaling. Under optimal operational conditions, results reveals that treated grey water samples with an upflow-downflow siliceous sand/marble waste filtration system may be considered as a good and an excellent water quality suitable for irrigation purpose. However, treated grey water was found not appropriate for industrial purpose due to high concentrations of calcium and sodium that can generate foaming and scaling harm to boilers. These results suggest that treated grey water with an upflow-downflow siliceous sand/marble waste filtration system would support production when used as irrigation water.

Phosphate mine wastes reuse for phosphorus removal from aqueous solutions under dynamic conditions.

Phosphate mine slimes (PMS), an abundant waste generated from phosphate mines, was used in this study as a cost-effective adsorbent to investigate the phosphate anions removal from synthetic and urban secondary treated wastewater solutions. Dynamic experiments using laboratory reactors were carried out to study the effect of phosphate influent concentration, PMS dosage and feed flow rate on phosphate removal and a kinetic model was used to determine the phosphate mass transfer coefficients. The results show that the phosphate removal increases with influent phosphate concentration and PMS dosage. The feed flow rate has no significant effect. On the other hand, the phosphate removal from wastewater is less efficient than the synthetic solution due to anions competition process. The evaluation of phosphates mass transfer coefficients confirms the presence of anion competition phenomena and the necessity of increasing PMS dosage to provide more adsorption sites. The cost-effective and high adsorptive capability of PMS make them attractive materials for phosphate anions removal and recovery from secondary treated wastewaters with the possibility of agronomic reuse as fertilizer.

Biosorption characteristics of phosphates from aqueous solution onto Phoenix dactylifera L. date palm fibers.

Phosphates are very important basic materials in agricultural and other industrial applications. The removal of phosphates from surface waters is generally necessary to avoid problems, such as eutrophication, particularly near urban areas. This paper is focused on the sorption of PO4(3-) ions from aqueous solution onto date palm fibers as a raw, natural and abundantly materials. A series of batch tests were conducted and the influence of contact time, initial phosphate concentration, pH of the solution and adsorbent dosage on PO4(3-) specie removal was investigated. FT-IR spectroscopy, scanning electron microscopy (SEM)/energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM) analysis of the date palm fibers before and after phosphates biosorption and desorption studies were investigated to confirm the mechanism of the retention of phosphates. Results indicate that PO4(3-) uptake increased with increased initial phosphate concentration and decreased with increased pH values. The results showed that the highest phosphates adsorption capacity (4.35 mg/g) was found at pH 6.8, for an adsorbent dosage of 6g/L, initial phosphate concentration of 50mg/L, under a constant temperature of 18 degrees C+/-02, and the equilibrium state was reached within 120 min of exposure time. The relatively low cost and high capabilities of date palm fibers make them potentially attractive adsorbents for the removal of phosphate from aqueous solution.

Date-palm fibers media filters as a potential technology for tertiary domestic wastewater treatment.

A number of municipal wastewater treatment systems were developed to improve effluent water quality, however economic aspects should be considered. This study was thus carried out to investigate the application of date-palm fibers filtration as an efficient method to economically remove turbidity, phosphorus, organics in term of COD and helminth eggs of secondary domestic wastewater from an activated sludge treatment process. Column experiments were investigated to study the efficiency of date-palm fibers filters media used in this work for the removal of targeted matter under operational conditions (flow rate, filter depth, and diameter of the fibers). The results indicate that diameter of the fibers had the most significant factor affecting the removal of targeted matter. Pilot test results indicated that date-palm fibers filtration removed up to 54.9% of turbidity, 80.6% of COD, 57.7% of phosphorus and 98% of helminth eggs. Definitely, it could be concluded that the date-palm fibers could offer an appreciable economic and environmental potential, which should be in a position to effectively contribute to the valorisation of such as date-palm by-products for domestic or industrial wastewater treatment in southern of Tunisia.