Naaila Ouazzani

Removal of organic pollutants and nutrients from olive mill wastewater by a sand filter.

The aim of this work was to examine the performance of a sand filter in treating modern olive mill (OMW) effluents after dilution with domestic wastewater on a one-to-one basis. The experimental pilot consisted of a column of opaque PVC, and the sand filter was filled with 50 cm of sand and 10 cm of gravel in the top and the bottom of the filter. The alimentation (4 cm/day) was done sequentially following a 1 day wet/3 days dry cycle. The OMW effluent was very acidic with a pH of 4.12, and had high concentrations of phenolic compounds (7.2g/L) and total chemical oxygen demand (65 g/L). The percolation of the diluted OMW through the sand filters caused an increase in pH from 4.84 to 8.25 and a 90% removal of total suspended solids. The sand filter treatment also led to important reductions in organic matter (90% of total COD, 83% of dissolved COD and 92% of phenolic compounds) and nutrients (91% of Kjeldahl-nitrogen, 97% of ammonia-nitrogen, 99% of nitrate-nitrogen and 99% of phosphates). The flow rate became very low indicating clogging of the sand pores after 10 weeks. HPLC analysis of the diluted OMW before and after passage through the sand filter showed an important reduction in the toxic monomeric compounds after the treatment.

Removal of phenolic compounds from olive mill wastewater by adsorption onto wheat bran

AbstractThe use of wheat bran for the removal of phenolic compounds from olive mill wastewater (OMW) at different adsorbent doses (10–60 g/L), pH (3–11), and contact time (0.25–24 h) was investigated. Our findings demonstrate that wheat bran, an inexpensive and easily available biomaterial, can be an alternative for the more costly adsorbents used for the removal of phenolic compounds from OMW. Increase in the wheat bran dosage from 10 to 50 g/L significantly increased the phenolic compounds adsorption rate from 45 to 67%. Increase in pH to high alkalinity resulted in an increase in the phenolic compounds’ adsorption capacity. The adsorption process was found to be relatively fast, and it reached equilibrium in 4 h of contact time. The Freundlich and Langmuir adsorption models were used for the mathematical description of the adsorption equilibrium and it was found that the experimental data fitted very well in the Freundlich model. Batch adsorption models based on the assumption of the pseudo-first-order...

Heavy Metal Contamination and Mobility at the Mine Area of Draa Lasfar (Morocco)

The present study represents a first insight into the Draa Lasfar mine (Marrakech) to assess the possible diffusion of heavy metals and to predict the risk of their mobility in the surroundings of the mine area. The edaphologic parameters pH, electrical conductivity (EC), loss on ignition (LOI) and CaCO 3 were measured according to standard methods, whilst heavy metals concentration was determined by FP-XRF. Concentration enrichment ratios (CER) were calculated in order to estimate the anthropogenic contribution of target pollutants determining As, Cu, Pb and Zn as the main pollutants, whereas Ba, Ca, Fe, K, Mn, Rb, Sr, Ti and Zr were considered lithogenic components. GIS contour maps of pollutants using CER data, showed the most polluted areas at the vicinity of the mine, especially at the northwest area, probably linked to weathering effects and topography of the area. Particle size studies revealed that As, Pb and Zn are part of the mineral ore while Cu behavior corresponded to an anthropogenic origin. Additionally, mobility assays employing single leaching tests indicated a greater mobility of As and Zn rather than that of Pb and Cu due to their lower adsorption process in the soil, independently of their respective concentration.

Removal of bacterial indicators and pathogens from domestic wastewater by the multi-soil-layering (MSL) system

Abstract This paper presents the performance and behavior of a multi-soil-layering (MSL) system to remove fecal contamination bacteria indicators and pathogens from domestic wastewater. The experimental setup was performed using a laboratory-scale MSL system (depth 30 × width 36 × height 65 cm). The MSL system was composed of soil mixture blocks (SMB) arranged in a brick-like pattern and surrounded by permeable gravel layers (PL). The SMB comprised sandy soil, charcoal, sawdust and metal iron at a dry weight ratio of 7:1:1:1. The hydraulic loading rate was 200 L m−2 day−1. Bacteriological analyses comprised total bacterial count at 22 and 37°C, fecal coliforms, total coliforms, Escherichia coli, streptococci, intestinal enterococci and pathogenic bacteria: Clostridium sp., Staphylococcus sp., Pseudomonas sp. and Salmonella sp. The best removal efficiency was achieved for Staphylococcus sp. by 1.42 log unit, while the lowest removal efficiency was found for E. coli by 1.01 log unit. The mean removal efficiencies of total suspended solids (SS), biochemical oxygen demand (BOD5), chemical oxygen demand (COD), total nitrogen (TN) and total phosphorous (TP) were 93, 86, 81, 78 and 80%, respectively. Based on these results, the MSL system could efficiently remove organic matter, phosphorus and nitrogen. However, the performance to reduce bacterial indicators and pathogens was still moderate.

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).

Two-stage vertical flow multi-soil-layering (MSL) technology for efficient removal of coliforms and human pathogens from domestic wastewater in rural areas under arid climate

This paper investigates the removal efficiency of organic matter, nitrogen, phosphorus, coliforms and pathogens from rural domestic wastewater in a two-stage vertical flow multi-soil-layering (MSL) system. The effects of wastewater quality, season and arid climate conditions on pollutants removal efficiency by the system were examined for one year. The experimental setup included two similar MSL systems composed of two layers: soil-mixture-layers (SML) and gravel permeable layers (PL) that are arranged in a brick like pattern. The applied hydraulic loading rate was 1000Lm-2day-1. Results showed that most of the physicochemical contaminants elimination occurred while the wastewater percolated through the first MSL stage. The second stage demonstrated an improvement in the reduction of all pollutants, especially fecal bacteria indicators and pathogens. The mean overall removal rates performed by the two-stage MSL system were 97% for TSS, 96% for BOD5, 91% for COD, 96% for TN and 95% for TP. For bacterial indicators, the combination of two-stage MSL system achieved high log removals between 2.21 and 3.15 log units. Contaminants reduction processes in MSL technology are more dependent on internal than external environmental factors. The effectiveness of the two-stage MSL system to treat domestic wastewater was strongly influenced by wastewater quality. Significant relationships between influent contaminants level and their removal efficiency were found. The efficiency of MSL technology to reduce contaminants is not sensitive to season and air temperature fluctuations. This is due to the capacity of MSL system materials to withstand the air temperature variation, which highlights one of the advantages of MSLs technology. Wastewater quality is the most important factor affecting the removal of contaminants in the MSL, which could be a critical parameter to considered when designing MSL system. Two-stage MSL system achieved a high treated wastewater quality amenable for treated wastewater reuse in agriculture recommended by Moroccan code of practice. Therefore, the combination of two-stage vertical flow MSL system could be considered an efficient and promising domestic wastewater treatment solution in arid countries to promote environmental protection and wastewater reuse.

Essays of phosphorus recovery into struvite from fertilizer industry effluents

AbstractThe studied Fertilizer industry effluent contains high concentration of phosphorus in the range of 228–1025 mg L−1, It is discharged in the surrounding sea without any preliminary treatment. Therefore, it constitutes a source of pollution to the coastal environment. This effluent contains also an important fluoride concentration. This quantity of phosphorus could be used to produce phosphorus fertilizer. So, the objective of this study was (i) to minimize fluoride concentration in fertilizer industry effluent and (ii) to recover phosphates from this effluent into the form of struvite (magnesium ammonium phosphate). To force the formation of struvite, ion was added by using ammonium chloride (NH4Cl). A preliminary study showed that fluorides were transferred into solid phase at pH 4. At this value of pH, the degree of fluoride recovery amounted to 95.62%. In the second stage, experiments were conducted to examine the effects of pH and N/P molar ratio on the removals of and by forming struvite. The ...

Impact of fertilization by natural manure on the microbial quality of soil: Molecular approach

The quality of soil is strongly bound by several interactions between chemical and biological components, including microbial composition, which are a key importance for soil performance. Cultural activities have a huge induction on soil health, through both modification of physicochemical proprieties and changing on soil microbial communities. This usually affects the safety of soil, and then the crop production and water. In the present work, the information on bacterial community composition was determined from a set of 6 soils collected from 2 farms in agricultural land of Marrakech (Morocco), one of which used poultry manure (PM) and the other cow manure (CM) as fertilizers. To profile this structure of the bacterial community Denaturing Gradient Gel Electrophoresis (DGGE) of 16S rDNA fragments has been used. These amendments resulted in the appearance of several novel bands and different relative intensities of bands between the control station and other sites studied. The stations most affected are those receiving a supply of manure rather high, which results in an organic and bacterial load in the soil. The results showed a bacterial diversity very important indicating a fecal contamination like Bacteroides, Pseudomonas, Staphylococcus,… etc. Bacteria pertain to the phylum Firmicutes and Bacteroidetes were noted to be the dominant ribotype in amended soil. Moreover, this work demonstrates also the existence of pathogens strains in soil amended by poultry manure (PM) belonging to the Clostridiales order and Pseudomonadales. The pathogenic bacteria detected posing a hazard of human contagion when they are used for soil practice.

Assif El Mal River: source of human water consumption and a transfer vector of heavy metals

AbstractThe mining and metallurgical mines that were abandoned with their residues constitute a source of metal pollution affecting the quality of water resources and soil. It is the case of an abandoned mining site Assif El Mal drained by the Assif El Mal River. In fact, these waters are a source of consumption without any treatment by the local population either directly or through their storage in reservoirs. A spatial variation of physicochemical parameters is determined to follow and monitor the behavior of some metals (Pb, Zn, Cu, and Al), from the abandoned mining district, in water and sediment samples along the river till the reservoirs. Also, an assessment of metal contamination level and toxicity of water is studied using the sequential extraction procedure (BCR). The results showed that the metallic load in water exceeds standards for human consumption, especially in the vicinity of the mine and the storage tanks. These levels range from 0.3–17, 0.02–0.05, 0.3–2.8, 0.03–0.1, 2.6–5.1 mg L1, res...

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

ABSTRACT 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.