Abstract: Background and Objective: The difficulty of sanitizing wastewater as it arises acutely in small communities, rural areas etc., requires that appropriate solutions be taken. The discharge of raw wastewater into the wild in Morocco accounts for nearly 54% on the coastline, reflecting the impact of a lack of hygiene and sanitation for the population and the environment. To improve the treatment of wastewater in rural areas that lack sanitation systems, the aim of this study was to introduce 2 anaerobic bioreactors in a pilot wastewater denitrification process to determine if those bioreactors could help decrease the chemical oxygen demand and nitrate levels in the wastewater. Materials and Methods: During operation, the decanted primary effluent separately supplied the 2 anaerobic bioreactors (hereinafter "bioreactor 1" and "bioreactor 2": The bioreactor 1 was fed with external nitrate plus the nitrate present naturally in the primary effluent, whereas, the bioreactor 2 was just fed with nitrate from the primary effluent) with an ascending flow. This allowed the annual average organic loading rate (chemical oxygen demand) of 0.652 g/day to be applied to the bioreactors. The primary effluent nitrate load applied to the bioreactors ranged from 1.94×10–3-14×1.10–3 g/day. In addition, 600 mg L–1 of nitrate was added in the bioreactor 1 treatment throughout the experiment at a 6 h hydraulic retention time. Data was statistically analyzed by one-way ANOVA using SPSS. Results: The overall organic loading rate in effluents treated with bioreactor 1 was 0.036 g m–3 day, a 72.16% reduction and 0.064 g m–3 day, a 48.9% reduction, for ARIBB 2. An average nitrate reduction performance of 80.31% was observed for bioreactor 1 and 42.81% for bioreactor 2 at the end of the experiment in June. Conclusion: The bioreactor 1 with nitrate addition showed better performance than the nitrate-free bioreactor 2, compared with the different chemical oxygen demand (COD) loads and environmental conditions. The relatively low cost of external nitrate facilitates access to the process.