By using an advanced anaerobic filter-contact aeration Gappei-shori Johkaso (AFAJ), a small-scale wastewater unit used in Japan, experiments of the treatment of the wastewater mixed with domestic wastewater and disposer wastewater which came from washing water of crushed garbage by disposer were made. After the introduction of disposer wastewater into domestic wastewater, BOD, TN and SS loads increased to 1.7 times, 1.1 times and 1.7 times, respectively. Results showed that in the 5-person-use type AFAJ, no remarkable decrease appeared to the BOD and SS removal efficiencies after introduction of disposer wastewater into domestic wastewater, however, TN removal efficiency decreased significantly. As a result, effluent BOD and TN concentrations were much higher than 20 mg·l−1. On the other hand, the 7-person-use type AFAJ, whose volume was 35 % bigger than that of the 5-person-use type AFAJ, could treat the above wastewater to be less than 20, 10 and 20 mg·l−1, respectively. In addition, it was shown that not many changes took place in the kinds and occurrence frequencies of protozoa and metazoa after the addition of the disposer wastewater, which suggested that the addition of disposer wastewater had increased the BOD and SS loads while it did not lead to much change in the component of the domestic wastewater.