Solid waste disposal is one of the major environmental issues facing Morocco. More than 5 million tons of solid waste is generated across the country, with annual waste generation growth rate reaching 3%. From this waste, there is production of fresh leachate with a high level of chemical oxygen demand (COD). The authors studied the removal of pollution from municipal solid waste fresh leachate using a technique of continuous and discontinuous aeration in order to predict the efficiency of a low-cost biological treatment for this type of effluent. The physico-chemical characteristics of the leachate showed that the pollution load has high levels of COD, biological oxygen demand (BOD5), phenol and surfactant. A removal of 90 and 60% of surfactant was obtained during discontinuous and continuous aeration, respectively. The phenol concentration decreased from 600 to 220 mg/l corresponding to 63% of phenol removal by aeration. This was also accompanied by a change in pH and sludge biodegradation. Discontinuous aeration for a period of 9 d achieved a removal efficiency of COD and BOD5 of 44 and 39% that corresponds to the removal of 19·92 g/l of COD and 7·05 g/l of BOD5, respectively.