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Phosphorus Treatment of Reject Water Using Thickened Water Works Sludge
- 언어ENG
- URLhttps://db.koreascholar.com/Article/Detail/342475
Three hundred thousand tons per year of water works sludge are produced in Korea. End disposal of the sludge is mainly based on recycle such as supplementary material for cement kiln, raw material for construction materials and fill material. The dry clarifier sludge organic content is about 30% and the major elements determined are aluminum(about 14%), iron(about 4%), potassium(1.8%), and manganese(0.5%). The recovery of coagulant has high economic advantage and recommended as a suitable treatment option for the disposal of water works sludge. Chemically, coagulant(aluminum) recovery from the water works sludge is a simple process. This process is however, somewhat complicated by pH control in the mixture of dewatered clarifier sludge and sulfuric acid solution. Also, the thickened water works sludge(TWS), which is withdrawn from the bottom of the thickener in water works plant, is difficult to dewater. In addition coagulation is used to remove total phosphorus(T-P) from municipal wastewater in oder to strengthening discharge water quality standard for T-P in municipal wastewater treatment plant(MWTP). Nevertheless it has the drawback of producing a large amount of sludge which together with the coagulants such as alum and polyaluminum chloride used to treat T-P in municipal wastewater increases the operating cost. Reject water originates from the dewatering of digested sludge in the MWTP. It contains heavy metals and large amounts of nutrients such as phosphorus and nitrogen. Traditionally, reject water is recycled back to the main flow line on of the MWTP. Although this method seems to be simple, it also has its drawbacks. First of which is the increase in the load of the MWTP as the reject water characteristics is very much different from the normal municipal wastewater. The objective of this study is to investigate the effectiveness of thickened water works sludge as an adsorbent of phosphorus from the reject water. In this study, batches of experiments were conducted to investigate the effect of dosage of TWS for reject water on its phosphorus adsorption properties. Increasing the TWS dosage to 30%(vol/vol), T-P and COD of reject water decreased to 55% and 20% respectively. Experimental results show that the potential of the TWS as coagulant in phosphorus and organic matter immobilization, thus converting they from rejector water to a useful material in pollutant control.
