Study On The Technology Of Phosphorus Removal With Waste Residue

Three types of residue, blast furnace slags, red mud and gypsum, were used as sorbents in phosphorus(P) removal tests to find out their adsorption capacity and principles as basic theories in the following tests.Column study was carried out with blast furnace slag. The main results are summarized as following:1. Blast furnace slag, red mud and gypsum are all efficient in P removal. Their P adsorption capacity is in the sequence blast furnace slag- red mud- gypsum. Blast furnace slag has the maximum adsorption capacity. Gypsum is less than the former with an order of magnitude as P adsorption capacity.2. Time, G value, pH, concentration of adsorbents and adsorbate, size of adsorbents are all the function of P removal. In optimized conditions of simulated municipal wastewater treatment, P removal of red mud is 97.2% and only 26.8% of gypsum. Phosphorus can't be detected with the treatment of blast furnace slag.3. Column study of blast furnace slag shows that, with a column of +80～-10 mesh size, 1 inch diameter and 0.5m high to treat with 5mg/l P aqueous solution, after 10h P begin to leak out and the effluent is within national P regulations in 19h.4. Treated with HCl, the P removal capacity of red mud is enhanced, equilibrium time is reduced, the problem of high pH of effluent is settled; Treated with 8% of gypsum, quilibrium time is also reduced, it is more suitable in alkaline conditions for P removal, pH of effluent is reduced. In optimized conditions of simulated municipal wastewater treatment, P adsorption capacity is increased to 2.13mg/g with HCl treated red mud and 1.66mg/g with 8% gypsum treated red mud.5. With adsorption isotherm tests, Freundlich equation is suitable with red mud, Temkin equation and Langmuir equation is suitable with blast furnace slag, Freundlich equation and Temkin equation is suitable with HCl treated red mud, Temkin equation is suitable with gypsum.6. Kinetic models of P adsorption of blast furnace slag, red mud, HCl treated red mud, gypsum all follow pseudo second-order equation and related correlation coefficients are all up to 0.9965.