This paper presents the effects of the treatment the small wastewater volume in the sequencing batch reactor. Two parallel operating reactors in the pilot scale the authors were investigated. The first was a classical system of SBR and the other was a moving bed reactor SBBR. Both technological lines were treated the same volume of pre-treated domestic wastewater. Three series of experimental studies differed with each other in the length of the aeration cycle. The operation of reactors and the obtained results in both systems was statistically analyzed. It was found e high efficiency of carbon and nitrogen removal (respectively 90 and 62%). The SBBR reactor worked much stable and obtained a higher degree of nitrogen compounds removal. The phosphorus removal efficiency in series 3 was about 83%. Wastewater treated in this reactor characterized by lower content of the suspended solids. It provides a better operation of the hybrid reactor in sedimentation phase.