Abstract: At present, the mud disposal from subway pollutes the environment seriously and has negative effect on construction.The mud disposal will be regarded as the research object in this test.The flocculation effects of inorganic flocculant (calcium hydroxide, ferric chloride and the double mixing) on the mud disposal are researched.The results show that: (1) When the water content is 99%,the optimal dosage of calcium hydroxide and Ferric chloride solution is 0.32% and 1.70%,besides the optimal dosage of mixture (calcium hydroxide and Ferric chloride solution) is 0.18% and 1.30%.(2) When the water content is 98% the optimal dosage of calcium hydroxide and Ferric chloride solution is 0.36% and 2.50%, besides the optimal dosage of mixture (calcium hydroxide and Ferric chloride solution) is 0.24% and 1.50%.(3) When the water content is 97%, the optimal dosage of calcium hydroxide and Ferric chloride solution is 0.38% and 4.30%, besides the optimal dosage of mixture (calcium hydroxide and Ferric chloride solution) is 0.23% and 1.00%.

Key words: waste residue in the mud;inorganic flocculant;moisture content;flocculation effect