No abstract

The dangerous chemical contamination of the Sebou River Estuary by the untreated urban wastewater from the city of Kenitra has been the subject of an extensive and comprehensive characterization through the study of the physico-chemical qualities of effluent samples from eight different municipal wastewater collectors (A, B, C, D, E, F, G and H) using standard methods. The evaluated physico-chemical parameters include: flow rate, pH, temperature (T °), chemical oxygen demand (COD), biochemical oxygen demand (BOD5), suspended matter (SM) and electrical conductivity (EC). The characterization of the examined parameters displayed a moderately neutral pH level in the domestic wastewater collectors (B to H), nonetheless, collector (A) showcased an exceptionally alkaline pH that arrays from 8.1 to 9.6, which in turn impacts the electrical conductivity and temperature, to the point of occasionally reaching up to 30.3 °C in the collectorin question. Pertaining to the collected (COD) and (BOD5) results, their values significantly exceeded the Moroccan standards, especially in collectors A, G and F, exhibiting thus low biodegradability with a COD / BOD5 ratio exceeding 3. The characterization of municipal wastewater and the measurement of its flow made the estimation of the pollution quantity discharged at the level of the Sebou river estuary achievable, these data will subsequently be used in favor of modeling and monitoring the fate of pollution in the receiving environment.

Urban wastewaters from Kenitra had been discharged without prior treatment through six collectors into the Sebou estuary (60 km) causing in the process health and environmental problems up until WWTP was installed in 2020. The waste water treatment plant (WWTP) had to gather all urban wastewaters in order to go through treatment. Thus, the WWTP, situated 17 km from the mouth of the estuary, has become the only discharge point for treated domestic wastewater into the Sebou estuary. This study aims to model the Sebou estuary water quality and assessment of the impact of WWTP. Our study started with hydraulic modelling of the river using a 1D model (HECRAS 5.0.6), since water quality is strongly depending on hydraulic regime. HEC RAS has been calibrated and validated using hydraulic and morphological database of the years 2019 and 2021. The spatiotemporal evolution of hydraulic variables (water velocity, water level, etc.) was calculated by the hydraulic model and used in the water quality module to simulate the biochemical oxygen demand (BOD 5 ). Two scenarios were put under examination, one is a simulation of discharges of untreated wastewaters by six collectors (mean BOD 5 of 300 mg/L) and the second is a simulation of discharge after treatment at the WWTP (mean BOD5 of 24 mg/L). The simulation showed an impact of the tidal cycle and fresh water flows (coming from the upstream) on the urban wastewater discharges fate. Calculations of the BOD 5 provided by the model are in good agreement with field measurements. The first simulation results show that water quality of the Sebou River does not meet WHO standards (average quality about 7 mg/l of BOD 5 ). The second simulation shows that the treatment plant reduces the concentration of BOD 5 in the river to about 3 mg/l compared to the case before their installation, the quality of the water in the estuary is changing to become good after having been just average. In addition, the BOD 5 concentration downstream of the WWTP changes according to the tidal cycle. Finally, the results show the very positive impact of Kenitra's WWTP on the water quality of the Sebou River estuary.

It is necessary to understand the process of anaerobic digestion (AD) of sewage sludge and to find an adequate strategy to improve the efficiency of methane production. In this work, the production of methane and detailed properties of sludge are determined. The physico-chemical parameters of the digester 1 'D1' and the digester 2 'D2' remain in the optimal range of AD stability with a median value of pH (7.82; 7.93); Temperature (36.70; 37.10°C); alkalinity (3.52; 3.58 g/L); and volatile fatty acids (0.47; 0.52 g/L), respectively. This paper focuses on the performance optimization of the methane production by kinetic models of two continuous digesters in a wastewater treatment plant in Kenitra City, Morocco. Mathematical models used in anaerobic digestion are: Modified Gompertz, transference functions, and logistics functions. These kinetic models have benefitted experimental methane production for both digesters. Results show that all the models used are appropriate to optimize the kinetic parameters for producing methane, showing that the transference function is the most suitable model for predicting kinetic results.