Soil fertility and agro-physiological responses of maize (Zea mays) irrigated by treated domestic wastewater by hybrid multi-soil-layering technology.

The depletion of water resources has gained global attention, particularly in arid climates, where there is growing interest in reusing treated wastewater for irrigation. This study focuses on the impact of irrigating treated wastewater using a hybrid multi-soil-layering (MSL) technology on soil physicochemical properties and the agro-physiological characteristics of maize (Zea mays) cultivated in Morocco, a region characterized by arid conditions. To achieve this research goals, three plots were cultivated with Zea mays and subjected to irrigation with water of varying qualities: raw wastewater (RWW), treated wastewater (TWW), and well water (WW). This experiment ran for five months, covering one crop season. The physicochemical and microbiological parameters in the soil and water were investigated, and the agro-physiological characteristics of the maize crops were assessed. The findings revealed significant differences in physicochemical and microbial parameters within both water and soil, as well as in the physiological responses of the maize crop, among the three water treatments. TWW's quality met the permissible limits for direct wastewater discharge, as prescribed by Moroccan norms, making it suitable for potential irrigation reuse. Moreover, the higher content of key elements (Na, K, Ca, and Mg) in WW indicated that TWW was more suitable for irrigation. Zea mays irrigated with RWW and TWW exhibited a higher accumulation of protein and sugar content compared to WW irrigation. Furthermore, the biomass parameters, including root, aerial, and grain dry weight, showed a positive effect on Zea mays irrigated with RWW and TWW compared to WW. Total chlorophyll content, on the other hand, was highest in plants irrigated with WW, followed by TWW. Plants irrigated with RWW produced the highest amounts of nitrogen, phosphorus, and potassium. Conversely, plants irrigated with WW had a higher content of Ca, Na, and Mg. TWW yielded medium concentrations of N, P, K, Ca, Mg, and Na compared to RWW and WW, attributed to the nutrients provided by irrigation with TWW using the hybrid MSL technology. In conclusion, aside from their use as irrigation water, treated wastewater emerges as a valuable source of plant nutrients and soil fertilizers. They offer significant nutritive value, enhancing plant growth, reducing the need for additional fertilizer application, lowering mineral fertilization costs, and increasing the productivity of infertile soils. This highlights the potential of treated wastewater to improve agricultural sustainability in arid regions like Morocco.

Enhancing pollutant removal efficiency in urban domestic wastewater treatment through the hybrid multi-soil-layering (MSL) system: A case study in Morocco.

This paper evaluates the performance and potential of a full-scale hybrid multi-soil-layering (MSL) system for the treatment of domestic wastewater for landscape irrigation reuse. The system integrates a solar septic tank and sequential vertical flow MSL and horizontal flow MSL components with alternating layers of gravel and soil-based material. It operates at a hydraulic loading rate of 250 L/m2/day. Results show significant removal of pollutants and pathogens, including total suspended solids (TSS) (97%), chemical oxygen demand (COD) (88.57%), total phosphorus (TP) (79.93%), and total nitrogen (TN) (88.49%), along with significant reductions in fecal bacteria indicators (4.21 log for fecal coliforms and 3.90 log for fecal streptococci) and the pathogen Staphylococcus sp. (2.43 log). The principal component analysis confirms the effectiveness of the system in reducing the concentrations of NH4, COD, TP, PO4, fecal coliforms, fecal streptococci, and fecal staphylococci, thus supporting the reliability of the study. This work highlights the promising potential of the hybrid MSL technology for the treatment of domestic wastewater, especially in arid regions such as North Africa and the Middle East, to support efforts to protect the environment and facilitate the reuse of wastewater for landscape irrigation and agriculture.

Typology and classification of water quality in an intermittent river in a semi-arid Mediterranean climate.

The typology and classification of rivers are highly relevant concepts in the field of limnology and freshwater ecology. Water body typology systematically categorizes water bodies based on their natural attributes, while water body classification groups them based on specific criteria or purposes for management, regulatory, or administrative reasons. Both concepts play important roles in understanding and managing water resources effectively. This scientific article focuses on the ZAT River in Morocco as a model for studying low-flow and intermittent rivers. The objective is to develop an accurate model for the typology and classification of small, low-flow rivers into homogeneous classes based on natural and anthropogenic factors. The study also investigates the impact of human activities on altering the uniformity and reference nature of the water body. The typology of water bodies is carried out according to the European methodology specified in The European Commission's Water Framework Directive (WFD) in 2000. The classification of water bodies is conducted by assessing their chemical and biological quality using the weighted index (WI), the Iberian Biological Monitoring Working Group (IBMWP) index, and multivariate statistical methods such as principal component analysis (PCA) for confirming water quality assessment. The results indicate the possibility of dividing the basin into four water bodies. Water bodies show homogeneity in terms of chemical quality when human influence is minimal or during periods of high river flow. However, increased human influence and decreased river flows lead to heterogeneity in chemical quality, indicating an unstable state. This study is the first of its kind in arid and semi-arid intermittent rivers, where such an approach could be suggested to determine their typology and classification.

Investigation of the agroecological applications of olive mill wastewater fractions from the ultrafiltration-nanofiltration process.

Agricultural applications of olive mill wastewater (OMW) represent a critical challenge, consistent with waste recycling and the trend towards a more sustainable pattern of agriculture. In this context, an integrated study on the agroecological applications of OMW from the ultrafiltration (UF) - nanofiltration (NF) process was carried out. This process generated three fractions: UF retentate and NF permeate, depleted in salts and phenolic compounds, were studied for their fertilization and irrigation potential, while NF retentate, enriched in these elements, was studied for its potential as a bioherbicide. The phytotoxicity of the NF retentate fraction on two crops (maize and flax) was evaluated on seedlings growth and chloroplast pigments content. In addition, the induced defense responses in maize and flax seedlings were investigated by measuring two parameters: the activity of the detoxification enzyme glutathione-S-transferase (GST) and the concentration of polyphenols, as a component of the antioxidant defense strategy in plants. Biomass, height, and chloroplast pigments content decreased progressively with increasing NF retentate concentration. Conversely, an increase in GST activity and polyphenol concentration was observed. These results highlighted the ability of OMW to induce an oxidative stress on maize and flax seedlings, triggering a defense response through GST and phenolic compounds. On the other hand, in vitro tests on the phytotoxicity of the NF retentate fraction on the common weed Sinapis arvensis were carried out. No germination was observed even with the lowest dilution applied, thus establishing the first data about the selectivity of potential OMW-derived bioherbicides. On the other hand, UF retentate and NF permeate treatments led to a significant increase in maize growth: these fractions could then be considered as a promising organic fertilizer for degraded agricultural soils, as well as an alternative water source for crops irrigation.

A critical review on the electrosorption of organic compounds in aqueous effluent - Influencing factors and engineering considerations.

Despite being an old process from the end of the 19th century, electrosorption has attracted renewed attention in recent years because of its unique properties and advantages compared to other separation technologies and due to the concomitant development of new porous electrode materials. Electrosorption offer the advantage to separate the pollutants from wastewater with the possibility of selectively adsorbing and desorbing the targeted compounds. A comprehensive review of electrosorption is provided with particular attention given to the electrosorption of organic compounds, unlike existing capacitive deionization review papers that only focus on inorganic salts. The background and principle of electrosorption are first presented, while the influence of the main parameters (e.g., electrode materials, electrode potential, physico-chemistry of the electrolyte solutions, type of compounds, co-sorption effect, reactor design, etc.) is then detailed and the modeling and engineering aspects are discussed. Finally, the main output and future prospects about recovery studies and combination between electro-sorption/desorption and degradation processes are given. This review particularly highlights that carbon-based materials have been mostly employed (85% of studies) as porous electrode in organics electrosorption, while existing studies lack of electrode stability and durability tests in real conditions. These electrodes have been implemented in a fixed-bed reactor design most of the time (43% of studies) due to enhanced mass transport. Moreover, the electrode potential is a major criterion: it should be applied in the non-faradaic domain otherwise unwanted reactions can easily occur, especially the corrosion of carbon from 0.21 V/standard hydrogen electrode or the water oxidation/reduction. Furthermore, there is lack of studies performed with actual effluents and without addition of supporting electrolyte, which is crucial for testing the real efficiency of the process. The associated predictive model will be required by considering the matrix effect along with transport phenomena and physico-chemical characteristics of targeted organic compounds.

Productivity and nutritional and nutraceutical value of strawberry fruits (Fragaria x ananassa Duch.) cultivated under irrigation with treated wastewaters.

BACKGROUND: Agriculture represents a productive sector typically characterized by a high water demand, whereas freshwater (FW) availability is a problem of increasing concern in the world and FW resources are becoming insufficient for sustaining agricultural irrigation. The reuse of treated wastewaters (TWWs) for crop irrigation could be an efficient tool for reducing water shortage. Hence, the present study evaluated the food quality of Fragaria x ananassa (cultivar Camarosa) fruits irrigated with four types of treated wastewaters (TWWs). Strawberries were analysed for yield, sucrose, fructose, glucose, total soluble polyphenols (TSP), total monomeric anthocyanins (TMA), and antiradical and antioxidant capacity. In addition, a targeted quantification of the most representative phenolic compounds of strawberry was performed. RESULTS: TWWs complied the Italian ministerial decree 185/2003 for wastewater reuse, with very few exceptions, mainly represented by chloride concentrations (258-643 mg L-1 versus a legal threshold of 250 mg L-1 ). The reuse of TWWs reduced fruit yield (10-26%) compared to irrigation with tap water as a control. Irrigation with TWWs gave also rise to the decrease of total sugars (14-26%), TSP (2-10%) and TMA (29-49%). Individual phenolic acids, flavonols and flavanols were quite stable in response to the irrigation with TWWs, whereas anthocyanidins decreased significantly. CONCLUSION: Although TWWs negatively affected fruit quality, the nutritional and nutraceutical parameters determined in the present study were in line with data previously reported for strawberries purchased in the market or cultivated in research orchards, thus suggesting that the use of TWWs does not prevent the fruit marketability. © 2020 Society of Chemical Industry.

Predicting the concentration of total coliforms in treated rural domestic wastewater by multi-soil-layering (MSL) technology using artificial neural networks.

Many indicators are involved in monitoring water quality. For instance, the fecal indicator bacteria are extremely important to detect the water quality. For this purpose, to better predict the total coliforms at the outlet of a Multi-Soil-Layering (MSL) system designed to treat domestic wastewater in rural areas, a neural network model has been developed and compared with linear regression model. The data was collected from the raw and treated wastewater of a three MSL systems during a one-year period in rural village, in Al-Haouz Province, Morocco. Fifteen physicochemical and bacteriological variables have undergone feature selection to select the best ones for predicting the total coliforms concentration in the effluent of MSL system. Furthermore, 80% of the available dataset were used to train and optimize the neural model using repeated cross validation technique. The remaining part (20%) was used to test the developed model. The neural network indicated excellent results compared to the linear regression. The optimal model was a neural network with one hidden layer and 11 neurons, where the R2 was about 97%. The importance analysis of each predictor was established, and it was found that pH and total suspended solids had the greatest influence on the total coliforms removal.

Accumulation of heavy metals in metallophytes from three mining sites (Southern Centre Morocco) and evaluation of their phytoremediation potential.

The current study aims to perform a field survey of three abandoned mining sites in the southern centre of Morocco to assess the recent metal pollution in soils and accumulation potential of plant species. Native plants and soils were sampled at several sites in the studied mines and analysed for Cu, Zn, Pb and Cd concentrations. Soils in the investigated sites proved to be deficient in major macronutrients and to contain toxic levels of Cu, Zn, Pb and Cd. Botanical survey of the prospected sites showed the abundance of diverse plant communities (46 species and 19 families), with no obvious toxicity symptoms. Results showed that the concentrations of heavy metals were different in the same plant species and from plant species to another. Eight plants of 46 species namely Hirschfeldia incana (L.) Lagr.-Foss, Citrullus vulgaris (L.) Schradi, Portulaca oleracea L., Stipa capensis Thunb., Lactuca viminea (L.) J.Presl & C.Presl, Forsskaolea tenacissima L., Lycium intricatum Boiss. and Hammada scoparia (Pomel) Iljin were considered as the best-performing specimens due to their high ability to accumulate multiple metals in their shoots and roots without being affected by excessive metal contents. This was confirmed by the transfer factors generally higher than 1. Consequently, these tolerant and native plant species could be used as tools for an effective phytorestoration of metal-contaminated sites.

Characterization by fluorescence of dissolved organic matter in rural drinking water storage tanks in Morocco.

Water storage tanks, fed directly from the river through opened channels, are particular systems used for water supply in rural areas in Morocco. The stored water is used as drinking water by the surrounding population without any treatment. UV-visible spectroscopy and fluorescence spectroscopy (excitation-emission matrices and synchronous fluorescence) have been tested as rapid methods to assess the quality of the water stored in the reservoirs as well as along the river feeding them. Synchronous fluorescence spectra (SFS50), collected with a difference of 50 nm between excitation and emission wavelengths, revealed a high tryptophan-like fluorescence, indicative of a pollution induced by untreated domestic and/or farm wastewater. The best correlations were obtained between the total SFS50 fluorescence and dissolved organic carbon (DOC) and biological oxygen demand, showing that the contribution of humic-like fluorescent substances cannot be neglected to rapidly assess reservoir water quality in terms of DOC by fluorescence spectroscopy.

Phytoremediation of domestic wastewater using a hybrid constructed wetland in mountainous rural area.

The purpose of this study is to evaluate the efficiency of hybrid constructed wetlands (HCWs) in a rural mountainous area. The experiment was set up in small rural community named Tidili within the region of Marrakech, Morocco. The wastewater treatment plant was composed of three vertical flow constructed wetlands (VFCWs) working in parallel, followed by two parallel horizontal-subsurface flow constructed wetlands (HFCWs), with hydraulic loading rates of 0.5 and 0.75 m3/m2.d, respectively. The two units were planted with Phragmites australis at a density of 4 plants/m2. Wastewater samples were collected at the inlet of the storage tank and at the outlet of the whole system (VFCWs, HFCWs) stages. The main removal percentages of total suspended solids (TSS), biochemical oxygen demand measured in a 5-day test (BOD5), chemical oxygen demand (COD), total nitrogen, and total phosphorus were respectively 95%, 93%, 91%, 67%, and 62%. The system showed a very high capacity to remove total coliforms, fecal coliforms, and fecal streptococci (4.46, 4.31, and 4.10 Log units, respectively). Artificial neural networks (ANNs) were used to model the quality parameters (TSS, BOD5, COD) and total coliforms and fecal streptococci. Based on the obtained results, the ANN model could be considered as an efficient tool to predict the studied phytoremediation performances using HCWs.

Phytostabilization of polymetallic contaminated soil using Medicago sativa L. in combination with powdered marble: Sustainable rehabilitation.

This study uses an ecotoxicology approach to evaluate the effectiveness of combining powdered marble as an amendment, with phytostabilization by Medicago sativa L. on the neutralization of acidic mine tailings, and the stabilization of heavy metals. The mine tailings were collected from an abandoned polymetallic mine in Southern Morocco, and mixed with powdered marble as the following proportions, 25%, 50%, and 75%. Laboratory immobilization/stabilization tests showed that the application of powdered marble in the treatments led to a significant increase in pH, and significant reductions of Cu, Zn (99%), Pb (98%), and Fe (45%). Greenhouse experiments showed that plant growth in all treatments was significantly (p ≤ 0.05) less than growth in agricultural soil. Plant growth significantly (p ≤ 0.05) decreased as the proportion of powdered marble increased. The concentration of metals in plant roots were significantly (p ≤ 0.05) higher than those of shoots. Combining immobilization by powdered marble with phytostabilization by M. sativa L. could represent a viable method of rehabilitating acidic polymetallic mine tailings.

Assessment of heavy metals accumulation by spontaneous vegetation: Screening for new accumulator plant species grown in Kettara mine-Marrakech, Southern Morocco.

The present paper aims to perform a screening of native plants growing in Kettara mine-Marrakech (Southern Morocco) for its phytoremediation. Plants and soil samples were collected and analyzed for Pb, Zn, Cu and Cd concentrations at several sites in the mine. The results showed that the soil in the vicinity of Kettara mine is deficient in major elements and contain toxic levels of metals. Spontaneously growing native plants were botanically identified and then classified into 21 species and 14 families. Significant difference was observed among the average concentrations of four heavy metals (Pb, Zn, Cu and Cd) in plants (p ≤ 0.05). Six plants of 21 species namely Hammada scoparia (Pomel) Iljin, Hirschfeldia incana (L.) Lagreze-Fossat, Lamarckia aurea (L.) Moench, Calendula algeriensis Boiss. & Reuter, Aizoon hispanicum L. and Melilotus sulcata Desf. were considered as the best-performing specimens due to their high ability to accumulate multiple metals in their shoots and roots without sustaining toxicity. This was confirmed by the transfer factors generally higher than 1. Using the most common criteria to classify the hyperaccumulator plants, these species can be classified as new accumulator plants of many heavy metals and be potentially used as remediation tools of metal-contaminated sites.

Removal of Cr(III) from chrome tanning wastewater by adsorption using two natural carbonaceous materials: Eggshell and powdered marble.

In the present paper, eggshell and powdered marble, two carbonaceous materials, were used to remove Cr(III) ions from a real chrome tanning wastewater. The effects of initial effluent pH, adsorbent dose, contact time and temperature were studied. The maximum uptake of chromium ions was obtained at pH 5.0 with the dose 20 g L(-1) and 12 g L(-1) for eggshell and powdered marble respectively. Adsorption equilibrium was reached after 14 h contact time for eggshell and only after 30 min for powdered marble. Under these conditions, almost 99% Cr(III) was removed from chrome tanning wastewater having an initial concentration of chromium of 3.21 g L(-1). Kinetic data were satisfactorily described by a pseudo-second order chemical sorption model. The equilibrium rate constant was notably greater for powdered marble than for eggshell with 1.142·10(-3) (g mg(-1) min(-1)) and 0.041·10(-3) (g mg(-1) min(-1)) respectively. The adsorption isotherm were well described by a Langmuir model and showed that the interaction of chromium with the two adsorbents surface is a localized monolayer adsorption with a smaller energy constant for the powdered marble than for eggshell (0.020 (L mg(-1)) and 0.083 (L mg(-1)) respectively). The powdered marble was able to adsorb faster a large amount of Cr (III) in comparison to eggshell. The use of a standardized lettuce seed bioassay allowed evaluating a better effectiveness of the Cr adsorption on the powdered marble, removing up to 40% of the treated effluent toxicity than by eggshell 25%. The powdered marble could be considered as an effective, low cost carbonaceous material to be used for chromium removal from tanning wastewater.

Eco-friendly management of harmful cyanobacterial blooms in eutrophic lakes through vertical flow multi-soil-layering technology.

Eutrophication has led to the widespread occurrence of cyanobacterial blooms. Toxic cyanobacterial blooms with high concentrations of microcystins (MCs) have been identified in the Lalla Takerkoust reservoir in Morocco. The objective of this study was to evaluate the efficiency of the Multi-Soil-Layering (MSL) ecotechnology in removing natural cyanobacterial blooms from the lake. Two MSL pilots were used in rectangular glass tanks (60 × 10 × 70 cm). They consisted of permeable layers (PLs) made of pozzolan and a soil mixture layer (SML) containing local soil, ferrous metal, charcoal and sawdust. The main difference between the two systems was the type of local soil used: sandy soil for MSL1 and clayey soil for MSL2. Both MSL pilots effectively reduced cyanobacterial cell concentrations in the treated water to very low levels (0.09 and 0.001 cells/mL). MSL1 showed a gradual improvement in MC removal from 52 % to 99 %, while MSL2 started higher at 90 % but dropped to 54% before reaching 86%. Both MSL systems significantly reduced organic matter levels (97.2 % for MSL1 and 95.8 % for MSL2). Both MSLs were shown to be effective in removing cyanobacteria, MCs, and organic matter with comparable performance.

Unlocking the potential of bacterioplankton-mediated microcystin degradation and removal: A bibliometric analysis of sustainable water treatment strategies.

Microcystins (MCs) constitute a significant threat to human and environmental health, urging the development of effective removal methods for these toxins. In this review, we explore the potential of MC-degrading bacteria as a solution for the removal of MCs from water. The review insights into the mechanisms of action employed by these bacteria, elucidating their ability to degrade and thus remove MCs. After, the review points out the influence of the structural conformation of MCs on their removal, particularly their stability at different water depths within different water bodies. Then, we review the crucial role played by the production of MCs in ensuring the survival and safeguarding of the enzymatic activities of Microcystis cells. This justifies the need for developing effective and sustainable methods for removing MCs from aquatic ecosystems, given their critical ecological function and potential toxicity to humans and animals. Thereafter, challenges and limitations associated with using MC-degrading bacteria in water treatment are discussed, emphasizing the need for further research to optimize the selection of bacterial strains used for MCs biodegradation. The interaction of MCs-degrading bacteria with sediment particles is also crucial for their toxin removal potential and its efficiency. By presenting critical information, this review is a valuable resource for researchers, policymakers, and stakeholders involved in developing sustainable and practical approaches to remove MCs. Our review highlights the potential of various applications of MC-degrading bacteria, including multi-soil-layering (MSL) technologies. It emphasizes the need for ongoing research to optimize the utilization of MC-degrading bacteria in water treatment, ultimately ensuring the safety and quality of water sources. Moreover, this review highlights the value of bibliometric analyses in revealing research gaps and trends, providing detailed insights for further investigations. Specifically, we discuss the importance of employing advanced genomics, especially combining various OMICS approaches to identify and optimize the potential of MCs-degrading bacteria.

Monitoring of toxic cyanobacterial blooms in Lalla Takerkoust reservoir by satellite imagery and microcystin transfer to surrounding farms.

Cyanobacterial harmful algal blooms (CyanoHABs) threaten public health and freshwater ecosystems worldwide. In this study, our main goal was to explore the dynamics of cyanobacterial blooms and how microcystins (MCs) move from the Lalla Takerkoust reservoir to the nearby farms. We used Landsat imagery, molecular analysis, collecting and analyzing physicochemical data, and assessing toxins using HPLC. Our investigation identified two cyanobacterial species responsible for the blooms: Microcystis sp. and Synechococcus sp. Our Microcystis strain produced three MC variants (MC-RR, MC-YR, and MC-LR), with MC-RR exhibiting the highest concentrations in dissolved and intracellular toxins. In contrast, our Synechococcus strain did not produce any detectable toxins. To validate our Normalized Difference Vegetation Index (NDVI) results, we utilized limnological data, including algal cell counts, and quantified MCs in freeze-dried Microcystis bloom samples collected from the reservoir. Our study revealed patterns and trends in cyanobacterial proliferation in the reservoir over 30 years and presented a historical map of the area of cyanobacterial infestation using the NDVI method. The study found that MC-LR accumulates near the water surface due to the buoyancy of Microcystis. The maximum concentration of MC-LR in the reservoir water was 160 µg L-1. In contrast, 4 km downstream of the reservoir, the concentration decreased by a factor of 5.39 to 29.63 µgL-1, indicating a decrease in MC-LR concentration with increasing distance from the bloom source. Similarly, the MC-YR concentration decreased by a factor of 2.98 for the same distance. Interestingly, the MC distribution varied with depth, with MC-LR dominating at the water surface and MC-YR at the reservoir outlet at a water depth of 10 m. Our findings highlight the impact of nutrient concentrations, environmental factors, and transfer processes on bloom dynamics and MC distribution. We emphasize the need for effective management strategies to minimize toxin transfer and ensure public health and safety.

Quality and disinfection trials of consumption water in storage reservoirs for rural area in the Marrakech region (Assif El Mal).

Traditional reservoirs for water storage are important systems of water supply in rural areas of Morocco. These reservoirs are fed by rainwater and/or directly from rivers through open channels; the stored water is used without any treatment as drinking water by the surrounding population. The present study aimed to assess the physicochemical and bacteriological quality of stored water and the corresponding sediment in six traditional reservoirs (R1 to R6) located in the rural municipality of Assif El Mal. We tested two inexpensive methods of disinfecting the stored water: chlorination and solar disinfection in bottles. The results show a rise of organic and mineral concentrations. Regarding bacteriological quality, a critical contamination level was detected (8 × 10(5) CFU/100 ml in water and 9 × 10(7) CFU/g in sediment) according to the 2002 Moroccan Standards for drinking water (0 CFU/100 ml). In the disinfection tests, chlorine disinfection removed all studied germs after just 1 hour, and the solar exposure process removed the majority of bacteria (after 3 hours) except those with a resistant form (Clostridia).

A Comprehensive Review of Polysaccharide-Based Hydrogels as Promising Biomaterials.

Polysaccharides have emerged as a promising material for hydrogel preparation due to their biocompatibility, biodegradability, and low cost. This review focuses on polysaccharide-based hydrogels' synthesis, characterization, and applications. The various synthetic methods used to prepare polysaccharide-based hydrogels are discussed. The characterization techniques are also highlighted to evaluate the physical and chemical properties of polysaccharide-based hydrogels. Finally, the applications of SAPs in various fields are discussed, along with their potential benefits and limitations. Due to environmental concerns, this review shows a growing interest in developing bio-sourced hydrogels made from natural materials such as polysaccharides. SAPs have many beneficial properties, including good mechanical and morphological properties, thermal stability, biocompatibility, biodegradability, non-toxicity, abundance, economic viability, and good swelling ability. However, some challenges remain to be overcome, such as limiting the formulation complexity of some SAPs and establishing a general protocol for calculating their water absorption and retention capacity. Furthermore, the development of SAPs requires a multidisciplinary approach and research should focus on improving their synthesis, modification, and characterization as well as exploring their potential applications. Biocompatibility, biodegradation, and the regulatory approval pathway of SAPs should be carefully evaluated to ensure their safety and efficacy.

Phenolic compounds removal in table olive processing wastewater by column adsorption: conditions' optimization.

The annual production of wastewater from the olive table industry poses a serious problem owing to its high organic matter load, which is highly concentrated in phenolic compounds (PCs) and inorganic materials. This research used adsorption to recover PCs from table olive wastewater (TOWW). Activated carbon was employed as a novel adsorbent. The activated carbon was obtained from olive pomace (OP) and activated using a chemical agent (ZnCl2). Fourier transform infrared spectroscopy analysis (FTIR), Brunauer-Emmett-Teller analysis (BET), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) were applied to characterize the activated carbon sample. To optimize the biosorption conditions of PCs (adsorbent dose (A), temperature (B), and time (C)), a central composite design (CCD) model was used. An adsorption capacity was 1952.34 mg g-1 for optimal conditions with an activated carbon dose of 0.569 g L-1, a temperature of 39 °C, and a contact time of 239 min. The pseudo-second-order and Langmuir models as kinetic and isothermal mathematical models were proved to be more appropriate for the interpretation of the adsorption phenomenon of PCs. PC recovery was performed in fixed-bed reactors. The results of the adsorption of PCs from TOWW by activated carbon could be an effective process at a low cost.

Assessing the performance of a waste management system towards a circular economy in the Global South: The case of Marrakech (Morocco).

Waste management is essential for the safety and wellbeing of any society; it also helps to tackle global problems, such as climate change and resource scarcity. To support the evolution of waste management systems (WMSs) towards a circular economy (CE), assessment methods are applied. This paper shows, using the case of Marrakech (Morocco), how a novel holistic approach called WMS development stage concept (WMS-DSC) is applied to assess WMSs and determine measures promoting a CE. The approach enables a simplified derivation of measures that are useful to municipal decision makers and consists of five stages; stage 1 is equal to a WMS lacking essential WM elements and stage 5 describes a functioning CE. The approach was specifically designed to be transferable to other Global South cities through the categorization into these universal stages. The results from the WMS-DSC show that components related to energy recovery and waste recycling are classified in stage 1. For the latter, a slight development towards stage 2 can be assumed due to the planned activities in Marrakech. The components "collection and transport" and "prevention and reuse" are mainly in stage 2. Nevertheless, the components "governance", "sector and market" and "waste disposal" are assigned to stages 2 and 3 with a stronger trend towards stage 4. The results show that in Marrakech and Morocco, CE is still in its infancy, and with this current state, it is hard to achieve. However, 33 measures were determined to improve the WMS of Marrakech and promote a CE.