... suspended solids (SS) by Standard Method for the Examination of Water and Wastewater (1995), COD by potassium dichromate method, NH4-N by Nessler method, NO2-N by diazotization method, NO3-N and ... water was discharged from houses In spite of such fluctuation of BOD in river water, the BOD concentration of treated water was very small in all the MSL systems Fluctuation of T-N in river water ... households are located along the river and have discharged gray water directly and toilet water with imperfect treatment to the river, which caused pollution of the river 85cm 105 cm 10 10 10 10...