Municipal wastewater is a main cause of water pollution. This research was aimed to manage wastewater with an onsite treatment system. The combined membrane-trickling system is a modified tricking filter by an additional coated media bed with biodegradable polymer at the bottom part of the unit and followed up by the conventional uncoated media bed. Low rate trickling filter was designed. A diameter of 50 cm and 1.15 m height unit was fabricated as the studied unit. The media materials were rigid PVC elements of 0.5 inch diameter and 1 inch length making into a perforated wall of 35 opening (5 opening/rowX7 rows) each. The membrane-coated media was prepared by casting chitosan dope solution synthesized from shrimp shell on each piece of media as a thin membrane layer. The characteristics of the synthesized chitosan dope solution were as follows: viscosity 4200-4500 cP, degree of deacetylation 84.4% and molecular weight 1.8 MDalton. Raw municipal wastewater was taken from the equlization tank from Sipraya Water Quality Improvement Factory. It was after bar screen and rotating fine screen by which large and fine objects were removed. The BOD loading, COD loading, N-loading and P-loading were 0.03-0.124, 0.119-0.269, 0.01-0.025 and 0.019-0.03 kg/m3.d, respectively. For the combined membrane-trickling system with coated media bed of 10 and 20 cm, it was found that the organic and nutrient removal efficiency in terms of BOD, COD and T-PO4 3- increased from ~50%, ~55% and ~8% in the conventional trickling filter system to ~60%, ~65% and 15-20%, respectively. Little improvement on total Kjeldahl nitrogen removal was also obtained from 31-35% to 36-50%. The removal mechanism at the viscosity of coated media bed was due to the appearance of more appropriate biofilm to the wastewater characteristic. The chitosan membrane coated on the media laster for 12 days operation.