The anaerobic treatability of domestic wastewater was investigated using a lab-scale UASBR operated for about 15 months. Organic loading rates were varied in the range of 0.2 to I kg COD/m(3) d during the study. COD removals varied in the range of 67 to 87 % and effluent CODs were generally 50 mil at steady state operating conditions. Concentrations of ammonia and phosphorus in the UASBR effluent were not satisfied the discharge standards into surface waters. Chemical past treatment provided significant reductions both in ammonia and phosphorus.