This research project was initiated to refine the knowledge available on the treatment of municipal wastewater by combined anaerobic ponds and wetlands. To determine the treatment capacity of combined system, a pilot scale of anaerobic ponds and subsurface flow wetland was built and was monitored over one treatment year, from December 2006 to December 2007. The anaerobic pond systems consisted of two ponds, a conventional pond and an optimized pond which were combined with two subsurface flow wetland respectively. The conventional pond were built in common method and the optimized pond in two parts, Part one as digestion pit with 12 hours detention time and part two as anaerobic baffled pond with 8 across baffles and 36 hours detention time. The experiments started with a tracer study to find out the hydraulic characteristics of each pond. Two sfs wetlands with 2 day hydraulic detention time and bulrush plant were built. The applied wastewater was provided by municipal network in wastewater treatment plant of sabzevar. Biweekly water samples at the inlet and outlet of each component of the combined system were analysed for biochemical oxygen demand (BOD5), total suspended solid (TSS), total kjeldal nitrogen (TKN), total phosphor (TP) and total coliform (TC). The average removal efficiency of conventional and optimized ponds combined with wetland cells as follow: BOD5 (68.5%–88%), TSS (82.6%–96.3%), TKN (83%–93.2%), TP (83%–91%) and TC (94%–98%) respetively.
Constructed Wetland, Anaerobic Pond, Digestion Pit, Across Baffle
