Abstract: To deal with special gel structure and a minimal amount of phosphorus in poor phosphorus sludge effectively，a two-step chemical method for treating poor phosphorus sludge was studied，in which the first step was yellow phosphorus releasing by gel breaking，and the gel breaking efficiency of different media，such as ammonia，sodium hydroxide，hydrogen peroxide，and hydrochloric acid， was emphatically compared；the second step was phosphorus oxidation by adding calcium hypochlorite as oxidant.Results showed that: the gel breaking efficiency of strong alkaline medium was better than that of alkalescent media；strongly acidic medium was better than weakly acidic media；Overall，alkaline media were better than acid media.In consideration of safety，equipment，and many other factors，the hydrochloric acid-calcium hypochlorite compound system was finally selected to oxidize the poor phosphorus sludge.The optimum conditions were as follows:Add 2.4 mol/L hydrochloric acid 40 mL in per 20 mL wet basis poor phosphorus sludge，gel breaking under 60 ℃ for 30 min，and then add 5.0 g of calcium hypochlorite，reaction time 3 h.As a result，the gel structure was broken availably and the phosphorus removal rate reached above 99.6%.

Key words: poor phosphorus sludge, two-step chemical method, gel breaking, oxidation treatment