Inadequate sanitation and poor infrastructure for waterborne sanitation are common in many developing countries. The
anaerobic/aerobic baffled reactor (AABR) is a sustainable option for water sanitation in developing countries. In the present study,
a 2.50 m3 AABR reactor working with real municipal wastewater was monitored. Four sequenced chambers, the first three being
anaerobic and the fourth aerobic composed the AABR reactor. AABR efficiency and performance were examined during four
different periods. Organic and hydraulic load increases were adequately absorbed, provoking no instability in the system and
demonstrating good configuration for absorbing organic impacts. The AABR had a promising effect on COD removal, which led
removal values of total COD up to 74%, and total suspended solid (TSS) removal up to 79%. Regardless of the value on entering,
the pH from the reactor effluent remained close to 7 during the four periods, indicating good stability in the reactor.