Abstract: In order to advocate the low-carbon living style and reduce the emission of pollutants, low carbon and emission reduction of municipal wastewater were investigated. The chemical oxygen demand （COD） of several kinds of substance was measured, including liquid food, liquid condiment, liquid detergent and washing water of rice. The results show that the values of COD in these substances are rather high with the maximum of 2.28 × 10⁶ mg/L of cooking oil and the minimum of 1.36 × 10⁴ mg/L of washing water of rice, which is largely higher than the value of COD in municipal wastewater. The COD of these kinds of substance was also calculated through theoretical analysis, and the results show that the amount of COD through calculation is almost equal to that through measuring and the absolute relative deviation is less than 8%, which indicates that the measuring value is credible. The reason for the high COD is that there are large amount of organic compounds in these substance, and the suggestion is proposed through emission reduction calculation that every member in our society should lead a low-carbon life and reduce the emission of COD in daily life.

Key words: chemical oxygen demand （COD）, municipal wastewater, liquid pollutants in daily life, emission reduction, low-carbon