Study On Technology And Solution Chemistry Of Inorganic Ion Wastewater Deep Treatment

There exists water shortage in our country because of not enough water resources or serious water pollution in some places. The severe situation is driving us to purify wastewater and convert it into useful resources. At the same time, new technologies are urgent to be exploited, spread and applied, so that the wastewater purification and reutilization can be done in high efficiency of treatment, small investment and low expense of operation because our country is on lower economic level.Iron oxide coated sand (IOCS) is cheap, convenient for use and of adsorbability which common quartz sand does not have. The phosphorus removal (P removal) technology of magnetic seed flocculation-high gradient magnetic separation (MSF-HGMS) combines the thorough P removal of chemical methods with the high separation speed and efficiency of HGMS. In this research, deep treatment of heavy metal ion wastewater and phosphorus wastewater was conducted by the new filtering medium-IOCS and the new technology-MSF-HGMS respectively. Solution chemistry of wastewater treatment was also studied. The main content is indicated as following:(1) Repeated precipitation and heating vaporization were adopted to prepare IOCS. Iron content, binding ability of iron oxide layer on quartz sand substrates, specific surface area, surface morphologies and matter species of iron oxide layer etc. were measured, observed and analyzed. Heating vaporization was considered more efficient than repeated precipitation by comparing the consumption of ferric chloride for preparation and the surface properties of the IOCS.(2) Tests of Pb(II), Cd(II), As(V) and Cr(VI) ions' adsorption on IOCS were conducted. The effects of ion strength, pH value, coexisting ions etc. were investigated. The dynamic behaviors of Pb(II) and Cr(VI) ions' adsorption on IOCS, such as isothermal lines (including adsorption equations ) and adsorption velocity (including velocity equations ) were studied. IOCS was confirmed to be a good adsorbent of heavy metal ions by the filtering experiments of Pb( II) ion wastewater and Cr(VI) ionABSTRACTwastewater with IOCS and common quartz sand.(3) The effects of magnetic seed, aluminum sulphate and pH value on phosphorus adsorption, precipitation and coagulation were surveyed. The results made it clear that Al (III) ion as precipitant and coagulant was the main effect factor on P removal; as adsorbent magnetic seed had little effect on P removal, but made the phosphate precipitate sink faster; pH value had effect on both precipitation and adsorption.(4) Experiments were carried out for P removal from municipal sewage by MSF-HGMS. After a series of technological factors were inspected, the optimized conditions which were of high efficiency and low cost for P removal got to be known. Under the optimized conditions, some enlarged tests were completed, the results showed that the feed of a sewage plant was purified to comply with the first grade of national integrated wastewater discharge standard, and the drainage of a sewage plant was deeply purified to reach some reutilization standards. It has not been reported up to now that the technology of MSF-HGMS was used for deep P removal from municipal sewage.(5) The distributions of heavy metal ions, phosphate ions and aluminum ions, solubility of aluminum phosphate, and the effects of pH value on them were analyzed theoretically by solution chemistry calculation. Mechanism of heavy metal ions' adsorption on IOCS and mechanism of hetero-coagulation between phosphate precipitate and magnetic seed were studied theoretically, and also by potential and infrared spectra. Basic principle of contaminant removal from water by HGMS was summarized and expounded.