Study of Physicochemical and Bacteriological Quality of Treated Wastewater by the New Aourir Plant (Southwestern of Morocco) Using Activated Sludge Technology in a Semi-Arid Region

In order to use the purified wastewater for the irrigation of a golf course in the Taghazout area (Southwestern of Morocco), this study was conducted to evaluate the physicochemical and bacteriological quality of the treated wastewater in the new Aourir plant (Activated Sludge technology). In order to achieve these objectives, three types of water were analyzed: raw water (RW), biologically treated water (BTW) and water treated by ultraviolet radiation (UV-TW). The physicochemical parameters analyzed were Temperature, pH, Electrical Conductivity (EC), Dissolved Oxygen (DO), Chemical Oxygen Demand (COD), five-day Biological Oxygen Demand (BOD5), Total Suspended Solids (SS), Nitrate (NO3), and Orthophosphates (PO4). Otherwise, the analyzed biological parameters are Total Coliforms (TC), Fecal Coliforms (FC), Escherichia coli (E. coli), and Fecal Streptococci (FS). The physicochemical parameters showed that temperature is always lower than 30°C, the pH is close to neutrality and a strong fluctuation of the high electrical conductivity (2700 μS/cm) occurs in UV-TW. At all stages of wastewater treatment, COD, BOD5, SS, NO3 and PO4 were below the limit values recommended by Moroccan standards. The bacteriological results showed a high level of bacterial contamination in RW and BTW, but in UV-TW the loads did not exceed 3 log10. The average loads of TC, FC, E. coli and FC in UV-TW were 2.13, 1.67, 1.77, and 2 (log10 CFU/100ml) respectively. Activated sludge treatment combined with UV has demonstrated sufficient quality to reuse treated water in irrigation; however, the UV treatment requires control to avoid any effect on the microbiological and physicochemical quality of green spaces and groundwater.


INTRODUCTION
Following the development and growth of urban, agricultural and industrial activities in Morocco, the production of wastewater has become very important. This causes a great health and environmental risk. Therefore, the treatment of wastewater becomes a necessity for environment protection (Hachemi et al., 2012). The purpose of wastewater treatment is either to discharge into the natural environment or to reuse the water that must meet standards set by the authorities responsible for water resources management. According to Haité (2010), the volume of wastewater in Morocco is estimated at 900 million m 3 / year in 2020. The pollutant load of wastewater is estimated at around 131715 tons of organic load, 42131 tons of nitrogen and 6230 tons of phosphorus (Mandi et al., 2013). Morocco, like most of the southern Mediterranean countries, suffers from the scarcity of conventional water resources, which constitutes a social, agricultural, and economic problem. The water problem in these countries is the result of a combination of arid climatic Study of Physicochemical and Bacteriological Quality of Treated Wastewater by the New Aourir Plant (Southwestern of Morocco) Using Activated Sludge Technology in a Semi-Arid Region conditions as well as an increase in water needs due to population growth and the development of tourism. It is, therefore, necessary to provide alternative water sources for agriculture to replace the high quality water required for consumption (Angelakis et al., 1999). In this context, the reuse of treated wastewater seems to be a good alternative especially in irrigation. This resource is abundantly and permanently available. It has many advantages, notably reasonable cost compared to desalinating seawater or digging wells. It ensures the balance of the natural water cycle and protection of the environment, as has been proven in many countries of the Mediterranean region, such as Israel, Cyprus, Jordan and Tunisia (Angelakis et al., 1999). Despite the benefits of wastewater reuse, it could present significant risks for users and the environment ( of pollution control strategy, reuse of treated wastewater, and contribution to sustainable development (Tahri et al., 2015). In this context, The Anza-Taghazout sector in the Agadir region (southwestern of Morocco) is among the sectors benefiting from the new treatment plants: lamellar settling in Anza and activated sludge in Aourir. The setting up of wastewater treatment plants in this sector is a major step towards modifying the sanitary quality of the marine ecosystem in this area. The new station of Aourir using activated sludge technology is the first in its kind in the Agadir region, characterized by its semi-arid climate. This very low charge station located between Tamraght and Aourir will serve more than 61,000 citizens. The purpose of this study was to evaluate the possibility of reusing the treated wastewater from the Aourir treatment plant in the irrigation of green spaces. It mainly consists in estimating the overall organic pollution and the sanitary quality of the effluents. In order to ensure the proper adaptation of this treatment system with the semi-arid climate of the region, it is necessary, first of all, to identify the sources of pollution at the entrance of this station, and then to evaluate its purification performance. The results will be confronted with the Moroccan and European standards.

Geographical location of the study site
The Aourir treatment plant (30°32'44.189"N, 9°42'29.297"W) is located near the ocean, northwest of Aourir and about 700 m south of the Taghazout bay tourist resort located 12 km from the Agadir city and 8 km from Taghazout. The Aourir treatment plant covers an area of 2.5 hectares (200 × 125 m). Figure 1 shows the location of this treatment plant.

Description of Aourir treatment plant
The effluent treatment channels includes a water treatment system with pretreatments, biological treatment and tertiary treatment, as well as a sludge treatment and a stale air treatment (deodorization) line ( Figure 2). Conventional pretreatment consists in a succession of screening, grit removal and de-oiling, followed by a combined treatment between the biological system (Table 1), which consists in passing the treated wastewater into two aeration tanks for biological degradation of the organic matter by biomass, followed by a mechanical system which consists in decanting all the sludge in the clarification tanks. The biological treatment is the activated sludge type with a very low load. Tertiary finalization treatment consists in series of mechanical filtration operations (10-μm microfiltration) and UV disinfection ( Table 1). The total flow of treated wastewater would be around 7600 m 3 /d for 60 833 population equivalent at the project saturation horizon (2030), which corresponds to

Samples collection
A total of 63 samples were collected over 21 months; from April 2017 to December 2018. Monthly, three samples were collected (Figure 1). It included: raw water (RW) at entrance to the plant, biological treated water (BTW), and finally, treated water disinfected with ultraviolet radiation (UV-TW) at the exit of the UV reactors.

Studied parameters
The overall physicochemical parameters (T °, pH, dissolved O 2 and conductivity) were measured in situ using a "Conductivity Meter" and "pH-meter" by the THERMO Scientific electrode, and the BANTE electrode instrument for the measurement of dissolved oxygen. BOD 5 , COD, SS were measured on monthly composite samples (RW, BTW, UV-TW). For suspended solids (SS), the measurement method adopted was differential weighing by filtration on GFC filter and drying at 105°C (AFNOR, T90-105). The five-day biological oxygen demand (BOD 5 ) was determined by using the manometric method with a respirometer (types WTW), according to the AFNOR standard (AFNOR, T90-103). The chemical oxygen demand (COD) was determined with the oxidizability with potassium dichromate (AFNOR, T90-101). The determination of nitrates (NO 3 -) was performed with the method based on sodium salicylate (AFNOR T90-013

Statistical analysis
The relationship between the microbiological and physicochemical parameters was analyzed using the Pearson Correlation Test. The analysis of variance (ANOVA) was performed in order to compare the changes in the water quality at the inlet and outlet of the treatment plant, caused by the treatment system. The ANOVA test was used to compare the concentrations of each parameter between seasons, years and between treatment steps using SPSS statistics24 with a significance level of 0.05 and 0.01.

Physicochemical parameters
The monthly wastewater temperature is shown in Figure 3a Table 2 shows the evolution of COD in RW and UV-TW. It varies between 722.56 ± 11.43 mgO 2 /L (autumn of 2017) and 1344.90 ± 18.38mgO 2 /L (summer of 2018) with an average value of 1059±19.  The analysis of the NO 3and PO 4 3nutrient contents in the RW and UV-TW of the Aourir wastewater treatment plant (Table 3) shows that the average values are much lower than those usually found in domestic wastewater. The average concentration of NO 3in RW is around 2.039±0.15 mg/L, the highest seasonal concentration was recorded in the summer of 2018 (2.36±0.45 mg/L), while the lowest seasonal concentration was recorded in the autumn of 2017 (1.3±0.35 mg/L). For UV-TW, the average concentration was around 0.71±0.14 mg/L, the maximum value was recorded in the autumn of 2018 (0.9±0.14 mg/L), whereas the minimum was recorded in the autumn of 2017 (0.35±0.14 mg/L).
The mean values for PO 4 3in RW and UV-TW are 10.54 mg/L±0.18 and 7.22±0.18, respectively. For RW, the highest seasonal concentration was recorded in the summer of 2017 (12.79±0.07mg/L), the lowest seasonal concentration was recorded in the autumn of 2018 (9.42±0.09 mg/L). In 3recorded in the summer of 2017 and 1.77±0.06 mg/L is the lowest seasonal concentration recorded in the autumn of 2018 (Table 3).
The measured data of physicochemical parameters were statistically analyzed using ANO-VA. The statistical analysis indicates high significant difference between seasons of all measured parameters p<0.001, in all types of water. In addition, a high significant difference is observed between steps of treatment p<0.001. Table 4 shows that the values recorded for the COD/BOD 5 ratio is 2.25±0. 22 (Table 4); the mean value was 660.48 ± 77.01 mg/L. This result, as well as the other ratios, reflect the relatively high loads of organic matter transported by the Aourir effluent.

The bacteriological characteristics of the wastewater and the purified water of the Aourir station
The bacteriological analysis focused on monitoring fecal contamination germs, total coliforms, fecal coliforms, E. coli and fecal streptococci (Enterococci). The results presented in this section corresponds to the sampling period of 2017 and 2018 in RW, BTW and UV-TW for a possible evaluation of their abatement. The bacterial load in RW and UV-TW shows a strong fluctuation during the different seasons of the two sampling years for all bacterial parameters p<0.001. The highest concentration of total coliforms in RW was recorded in the summer of 2018 by 7.75 log 10 CFU/100 ml, and the lowest was recorded in the winter of 2017 by 6.36 log 10 CFU/100 ml (Figure 4 a). The annual average of total coliforms in RW is approximately 7.05 log 10 CFU/100 ml. This number decreases considerably in BTW with a value of 3.35 log 10 CFU/100 ml and in UV-TW with a value of 2.13 log 10 CFU/100 ml. The highest concentration of total coliforms in UV-TW was recorded in the spring of 2018 with a value of 2.30 log 10 CFU/100 ml, and the lowest was recorded in the summer of 2017 with a value of 1.92 log 10 CFU/100 ml. The average fecal coliform load in RW is about 6.47 log 10 CFU/100 ml and 1.67 log 10 CFU/100 ml in UV-TW (Figure 4 b). The highest concentration of fecal coliforms in RW was recorded in the summer of 2018 (7.27 log 10 CFU/100 ml), while the lowest was marked in the autumn of 2017 (5.88 log 10 CFU/100 ml). The fecal coliform concentrations in UV-TW reached the maximum in the summer of 2018 (1.96 log 10 CFU/100 ml) and the lowest abundance was recorded in the autumn of 2018 (1.51 log 10 CFU/100 ml).
For E. coli, a one-year sampling was performed from January 2018 to December 2018 (Figure 4 c). In RW, it shows an annual average concentration of 6.9 log 10 CFU/100 ml, the  highest concentration was marked in the summer season of 2018 (7.28 log 10 CFU/100 ml), while the lowest concentration was recorded in the winter of 2018 (6.08 log 10 CFU/100 ml). UV-TW does not exceed 1.77 log 10 CFU/100 ml as an annual average value, the highest load is recorded in the summer of 2018 (2.03 log 10 CFU/100 ml), and the lowest was recorded in the winter of 2018 (1.58 log 10 CFU/100 ml). The average number of fecal streptococci in RW is 6.02 log 10 CFU/100 ml, while UV-TW contain an average value of less than 2 log 10 CFU/100 ml (Figure 4 d). The highest concentration of fecal streptococci in RW was recorded in the summer of 2018 (6.65 log 10 CFU/100 ml) while the lowest concentration was recorded in the autumn of 2017 (5.38 log 10 CFU/100 ml). UV-TW recorded the highest abundance in the autumn of 2017 with a value of 1.76 log 10 CFU/100 ml, and the lowest in the summer of 2017 with a value of 1.15 log 10 CFU/100 ml (Figure 4 d). According to the statistical study, a significant difference p<0.001 between RW and UV-TW was found for the four indicators of fecal contamination.

Physicochemical parameters
Agadir is among the regions of the Moroccan kingdom most affected by the scarcity of conventional water resources. The reuse of treated wastewater seems a necessity to reduce the pressure on the groundwater. Currently, UV-TW from the Aourir wastewater treatment plant is reused to irrigate a golf course in Taghazout bay tourist resort. This study gives the bacteriological and the physicochemical quality of UV-TW, to evaluate the effectiveness of UV disinfection and to prevent their health and environmental risks.
Throughout the study period, the temperature of all types of water was below 30°C, which are favorable values for the operation of bioreactors (Adouani et al., 2015). The high fluctuation observed is due to climate change, the treatment stages, and the chemical and biological reactions. These recorded temperatures do not exceed the limit values for direct discharges to the receiving environment (Official Bulletin, 2002).Water temperature is an ecological factor with significant ecological impacts (Makhoukh et al., 2011). It is important in the aquatic environment and has an influence on physicochemical and biological reactions (Chapman, 1996). Bourouache et al., (2019), who monitored the performance of a percolation infiltration system in the same region, found that temperature is always below 35°C in different types of water, and concluded that this temperature is adequate for the proper functioning of anaerobic sludge digestion. The pH values in the different types of water are close to neutral. In general, despite the observed fluctuations, the pH evolution (UV-TW) is always between 6.5 and 8.4, which are considered limit values for direct discharges into the natural environment and a normal pH zone according to the quality standard for water intended for irrigation (Official Bulletin, 2002). In Algeria, a comparison study of two free biomass treatment plants (aerated lagoon and activated sludge) concluded that there is an asymmetric distribution of the pH values in both treatment plants. The aerated lagoon reflects an asymmetric distribution towards low pH concentrations, whereas the activated sludge reflects an asymmetric distribution towards high pH concentration values (Bachi et al., 2020). However, it should be noted that the pH values that are too acidic or too basic could affect the biological treatment processes. In this regard, Deronzier et al., (2002) reported that a drop in pH below 7 significantly slows nitrification. In addition, the pH values ranging from 5.6 to 8.6 promote the bacterial growth necessary for the biological degradation of organic pollutants (Maiga et al., 2006). The pH between 6.5 and 7.5 is generally recommended for wastewater treatment plants, as low pH promotes the growth of filamentous fungi and other organisms responsible for sludge flotation (Arcand et al., 2005).
The strong fluctuation of the electrical conductivity recorded in the RW and UV-TW can be -have recorded an increase in the concentration of electrical conductivity in the treated water at the outlet of the WWTP. They have enhanced this growth by the mineralization of organic matter by bacteria during the treatment process and by the chemical and geometrical properties of the use of sand in the percolation infiltration basins. The results obtained in this study are consistent with the work carried out on the Yemen activated sludge plant in an arid climate; this study concluded that electrical conductivity is slightly reduced by the treatment system, and that physical and biological treatments have a reduced effect on electrical conductivity (Merghem et al., 2016). The quality standards for irrigation water allows deducing that treated wastewater is acceptable for crop irrigation. Similarly, these average values are below 2700 μS/cm, which is considered the limit value for direct discharge into the receiving environment (Official Bulletin, 2002).
A strong increase in the concentration of dissolved oxygen in UV-TW is due to a good aeration of water, necessary for the development of aerobic microorganisms ensuring the oxidation of organic matter (Deronzier et al., 2002). However, in an activated sludge wastewater treatment, the dissolved oxygen (DO) contained in the treated water must be higher than 2 mg/l (Merghem et al., 2016). The respect of these thresholds (O 2 > 2 mg /l) creates favorable conditions for both total aerobic biodegradation and the establishment of the nitrification phenomena. It is important to note that dissolved oxygen is a good indicator of the degree of water pollution and the presence of aerobic bacteria capable of developing in the environment.
The suspended solids (SS) concentrations continue to change especially in spring and summer. In addition, the effluents from the Aourir plant reflect remarkable particulate pollution, especially in summer, which is explained by a major hydraulic spill due to significant domestic and tourist activity in the region. The recorded values remain below the direct discharge limit value (50 mg / L) throughout the monitoring period (Official Bulletin, 2002). It should be noted that suspended solids represent all mineral and organic particles contained in the water. It depends on the nature of the land crossed, the season, the precipitation, the nature of the discharges, etc. (Rodier et al., 1959). It causes the water turbidity and a reduction in light penetration. Turbidity also indicates the presence of suspended solids, but high turbidity allows microorganisms to attach to suspended particles, which protects them from treatment (Mouhanni et al., 2013). The removal of suspended solids was able to reach a maximum of 98% total removal in the UV-TW that underwent final filtration. This result is even higher than that of Hamoda et al., (2004) which managed to reach 70% removal of suspended solids after secondary water filtration. The same is true for Petala et al., (2006), who managed to achieve a turbidity removal percentage of about 45% after sand filtration, while the activated carbon process increased turbidity removal to more than 60%. The study conducted by Bachi et al., (2020) on the performance comparison of two free biomass treatment systems (aerated lagoon, activated sludge), showed that the SS removal rates were highest in the case of the activated sludge system (96.6%-93.4%) and the lowest in the case of aerated lagoon system (39.2%-67%) with an average difference of more than 43%. These results allow concluding that the combination of the investigated treatment system was successful in removing particulate pollution.
The importance of monitoring organic pollution parameters is summarized by the fact that BOD 5 (Biochemical Oxygen Demand) allows the evaluation of biodegradable organic matter present in water (Hassoune et al., 2006). COD (Chemical Oxygen Demand) is used to assess the concentration of organic or mineral matter dissolved or suspended in water, through the amount of oxygen necessary for their total chemical oxidation (Rodier et al., 1959). The results of biological oxygen demand (BOD 5 ) and chemical oxygen demand (COD) are related empirically to the oxidizable matter (Bali et al., 2010). An increase in the organic load was noticed during the second year of sampling and significant difference was recorded between the two sampling years p<0.001 (2017-2018). The concentrations of BOD 5 and COD in UV-TW are less than 100 mg O 2 /L and 500 mg O 2 /L, respectively, considered as a limit values for direct discharges into the natural environment. The treatment efficiency of the Aourir activated sludge can be summed up by the 95.5% and 91.8% abatement recorded for BOD 5 and COD, respectively. A great concordance between the obtained results and those of Abdulla et al., (2020), who worked on activated sludge system in Jordan, were noticed. They found that BOD 5 comes out with average values of 25 mg O 2 /L, and COD reaches an average value of 120 mg O 2 /L; these results were taken in 2017/2018 in the same period of our study.
The Agadir region has several treatment plants that treat most of the region's effluents. In order to have a general view on the treatment efficiency of the Aourir plant, it is interesting to compare the activated sludge system with other treatment systems in the region. Mimouni et al., (2011) followed the efficiency of percolation infiltration in the Bensergao plant. The organic pollution abatement was very interesting; BOD 5 reaches a rate of 99.9% and 92.8% for COD. Mouhanni et al., (2013) followed the M'zar plant also equipped with a percolation infiltration system and showed an important treatment efficiency with a BOD 5 reduction rate of 98% and 98% for COD, Bourouache et al., (2019) continued the follow-up and confirmed the efficiency of the fixed biomass treatment ( Table 8). The COD/ BOD 5 ratio is a very important factor in assessing the biodegradability of the wastewater. The ratio is below 3 which designates a domestic effluent indicating a good biodegradability of the oxidizable material (Boutayeb et al., 2012). The BOD 5 / COD ratio, gives more indication of the origin of wastewater pollution and its treatment possibilities (Benyakhlef et al., 2007). The values recorded show a high organic load and confirm the possibility of an easy biological treatment, being higher than 0.3. The BOD 5 /COD ratio indicates a dominance of organic matter (Bouknana et al., 2014). The SS/BOD 5 ratio remains within the normal range between one and three. The ratio confirmed the organicity of the effluent and provided the information on sludge production (Quevedo et al., 2012). The term "oxidizable matter" (OM) corresponds to a weighted average of two global parameters the COD and the BOD 5 , by assigning a double coefficient to BOD 5 (Rodier et al., 1959). The OM is a very useful parameter for assessing the pollutant load and possibility of connection of industrial plant to the municipal sewerage network. In reality, most organic materials become polluting only when they are found in excess in the environment (Bouknana et al., 2014).
Nitrate is the final product of aerobic stabilization of nitrogen compounds. It is considered the most stable oxygen compound present in water. In natural resources, the nitrate levels are often low (< 20 mg/l) (Baharvand & Daneshvar, 2019). The discharge of large amounts of wastewater is the most important source of nitrate to surface water more than to groundwater. The results of the nitrate content measurement of RW and UV-TW in the Aourir plant showed that the amount of nitrate in the treatment process is reduced. Moreover, they have indicated an acceptable result according to environmental standard threshold (< 30 mg/l). Consequently, the NO 3 removal efficiency is estimated at 63% during the water treatment process in the Aourir treatment plant. The concentrations of orthophosphates have significantly decreased in UV-TW; these values remain below the direct discharge limit value (10 mg/L) which demonstrates the purifying power of the activated sludge technique. However, this decrease is insufficient because it would be necessary to reach the values in the range of 0.6 to 1 mg/L to have a water with the same phosphate content as that existing in Moroccan rivers (Mimouni et al., 2011). The PO 4 3removal efficiency is estimated at 39% at the exit of the Aourir plant.

Bacteriological parameters
Water disinfection is a treatment that aims to reduce the presence of pathogenic microorganisms in water. In order to comply with Moroccan standards, the Aourir plant uses UV radiation to disinfect BTW. Several criteria affect the effectiveness of UV treatment, with the insufficient energy dose damaging the genetic material of the organism rather than destroying it (Collivignarelli et al., 2018). High SS can significantly reduce the effectiveness of UV disinfection (Sharrer et al., 2005). In this sense, previous studies have shown that certain types of bacteria can easily pass through the treatment process while remaining viable (Fonteneau et al., 2017). TC, FC, E. coli and FS enumeration results at the RW levels of the Aourir plant represent a maximum bacterial load of 7.75 log 10 CFU/100 ml, 7.27 log 10 CFU/100 ml, 7.28 log 10 CFU/100 ml, 6.65 log 10 CFU/100 ml, respectively. This load is of the same order of magnitude as that generally found in urban effluent (Shahalam, 1989;Mezrioui & Baleux, 1994). In UV-TW, the bacterial load is lower than in RW, the average concentration of TC, FC, E. coli, and FS is 2.13 log 10 CFU/100 ml, 1.67 log 10 CFU/100 ml, 1.77 log 10 CFU/100 ml, 2 log 10 CFU/100 ml. This research showed that the UV disinfection of the Aourir plant was sufficient to provide the water that meets the Moroccan standards. The combination of UV disinfection and microfiltration gave interesting results. After treatment, wastewater poses a potential risk to human health and the environment, so constant monitoring is necessary. The obtained results were compared with those of Petala et al., (2006), who worked with a conventional activated sludge process followed by a system composed of a moving bed sand filter, a granular activated carbon adsorption bed and ozonation system as tertiary treatment. They indicated that an ozone concentration of 7.1 mg/L in secondary effluents provoked a reduction of total coliforms to about 2.6 log 10 ; fecal coliforms to about 3.3 log 10 ; and to 0.7 log 10 of fecal streptococci. These results indicate that the disinfection applied in our case (UV) also has an effect close to that of ozonation. In turn, Lazarova et al., (1998), who studied disinfection technologies, indicated that 3-log removal of total coliforms, fecal coliforms and fecal streptococci were obtained by peracetic acid at 10 mg/L for a contact time of 10 min, by UV radiation at 35 mW.s/cm 2 . Despite these results, ozonation has the advantage of having a significant effect on all types of bacteriophages and protozoan cysts, even when low treatment doses and short contact times are applied. Climatic conditions play an important role in the treatment process (Joel et al., 2018), which is most evident in monthly temperature fluctuations. Indeed, during the summer seasons of the study, significant loads were recorded. In the Aourir plant, it appears that the initial bacterial loads and climate change were the main factors influencing the bacteriological quality of the treated effluent. In Morocco, there is no standard for fecal streptococci. Although these organisms are very useful in providing more information on fecal contamination in the water (Boehm et al., 2014). It is therefore necessary to ensure continuous monitoring to assess the effect of seasonal variations on the different bacterial loads. The FC/FS ratio is a more valuable information tool for assessing sources of pollution than using the FC densities alone (Raji et al., 2015). Geldreich (1966) indicated that this ratio (FC/FS) could be used to differentiate between the contaminations from human sources, (FC/FS > 4), domestic animals (FC/FS between 0.1 and 0.6), and wildlife (FC/FS < 0.1). In the performed study, the ratio of FC/ FS is around 3.39, which allows deducing that most of the pollution is of human origin. The abatement rates for fecal contamination indicators, recorded in the Aourir plant, are in agreement with the values found in the literature, which show that biological processes can reduce coliform abundance from 3 to 4 logarithmic units. It is in the order of 90% for activated sludge (Omura et al., 1989), 99% for extended activated sludge and for fixed culture reactors, and 99% for lagooning (Finch et al., 1986). These abatement rates are related to the settling rate, the hydraulic residence time, and the quality of the raw wastewater. In the case of this study, the rate of reduction of fecal contamination indicators seems very important for the different parameters. The efficiency of the treatment of Total Coliforms, Fecal Coliforms, Escherichia coli, Fecal Streptococci is in the order of 4.92; 4.8; 5.13 and 4.57 log 10 respectively, which equals an efficiency of 99.99% for all parameters. Therefore, it can be deduced that the adopted treatment represents a high efficiency and performance.

Correlation between physicochemical and microbiological parameters of raw and treated wastewater
The correlations between physicochemical and bacteriological parameters for both types of water (RW, UV-TW) are detailed in Table 6 and 7. For RW, the physicochemical parameters were not significantly correlated with the concentrations of TC, FC, FS and E. coli except for conductivity which is significantly correlated with the TC concentrations (r=0.612, p=0.034). For UV-TW, FC and E. coli concentrations have significant positive correlation with electrical conductivity and dissolved oxygen. For FC, a correlation of (r=0.659, p=0.020) with electrical conductivity, and (r=0.712, p=0.009) with dissolved oxygen. E. coli has a correlation of (r=0.695, p=0.012) with electrical conductivity and (r=0.602, p=0.038) with dissolved oxygen. SF also represents a significant positive correlation with dissolved oxygen of (r=0.797, p=0.002). The correlation between the physicochemical and microbiological parameters did not show a high correlation except for the dissolved oxygen and the electric conductivity. Contrary to Pearson et al., (1987)  who showed a correlation between the FC and the Temperature and the pH, it explains that the temperature and the high pH favor the mortality of coliforms in the waters. Other studies of seasonal variation in bacterial flora of the wastewater and soil in the vicinity of industrial area by Malik et al. (2002), recorded the effect of physicochemical parameters on the fecal coliform variability. The observed relationship between dissolved oxygen and fecal contamination indicator bacteria is directly related to the essential factors of aeration treatment where oxygen is an essential factor for treatment. The effect of physicochemical parameters on bacteria was also summarized in the study by Rosenfeld et al. (2006). He found that the load of fecal indicator bacteria is not only related to seasonal, spatial or source variability. It is also related to the fact that each type of bacteria dies at a different rate depending on environmental factors (temperature, salinity, nutrient concentration, predation, the presence or absence of bacteria, absence of bacterial toxins, solar radiation, coagulation, flocculation, and particle adsorption), all of which have an impact on the ultimate death of bacteria.

CONCLUSIONS
In Agadir, many studies have been conducted on the process of sand percolation infiltration on different aspects: physicochemical, microbiology and parasitology (Table 8). This research presents the specification to study a new system implemented in the region (activated sludge), and investigate its operation in a semi-arid climate. Monitoring of the microbiological and physicochemical parameters in all types of waters from Aourir treatment plant made it possible to assess their quality. The quality and quantity of wastewater that the Aourir plant receives depend essentially on the quantity of water consumed by the population. They also depend on the intensity of tourist activities according to the seasons. This causes fluctuations in the level of physicochemical and microbiological pollution of effluents ** -The correlation is significant at the 0.01 level (bilateral). * -The correlation is significant at the 0.05 level (bilateral). during the year. The following conclusions were drawn from this study: All parameters were in accordance with the Moroccan standards. UV-TWs distinguished for the watering of green spaces meet the criteria set by the Moroccan and WHO reuse standards. However, UV control is necessary in order to take appropriate preventive measures to reduce the health risk and prevent further pollution of green spaces and groundwater. As a perspective, the authors are planning to study the effect of reuse of treated wastewater on irrigated green spaces.