STUDY ON CALCIUM AND MAGNESIUM HARDNESS REMOVAL FROM WATER USING THE ALKALINE WASTEWATER FROM WASHING INCINERATOR ASH

摘要

The actions of alkaline wastewater (AWW) from washing incinerator ash at heat and electric power station (HEPS) as treatment agent for supplemental water are observed, and the association of calcium or magnesium bicarbonates in supplemental water and alkaline compounds in the wastewater is investigated. Main properties of the alkaline wastewater are also observed. It is shown that there is a certain amount of calcium hydroxide in the wastewater, and that the treatment of supplemental water with the wastewater results in the formation of difficulty soluble compounds, CaCO_3 and Mg (OH)_2, which precipitate out and are removed from water. The results also showed that other alkaline wastewater, including Na_2CO_3 and NaHCO_3, from the coking plant (CP) aadded as a promoter significantly enhanced the softening of water, but slightly increased pH values for the supplemental water. The influences of temperature and amounts of two alkaline wastewaters from HEPS and CP on hardness removal were investigated by factorial analysis. Best results gave up to 92.8% total (96.03% calcium) hardness removal.