PhosphorusRemovalwithHydrotalciteCompound

--An Application for Secondary Effluent of Human Excrement--
Tomonori Kindaichi*, Kazuyuki Nishimura**, Takane Kitao***
Kazumichi Kuzawa**** and Yoshiaki Kiso****
* Department of Urban and Environmental Engineering, Graduate School of Engineering, Hokkaido University
** Research Center for Material Cycles and Waste Management, National Institute for Environmental Studies
*** Department of Architecture and Civil Engineering,Toyohashi University of Technology
**** Department of Ecology Engineering,Toyohashi University of Technology
+ Correspondence should be addressed to Kazuyuki Nishimura:
(16-2 Onogawa, Tsukuba-city, Ibaragi 305-8506 Japan)

Abstract
Phosphate removal properties of hydrotalcite (HTAL) compound were examined for use as an adsorbent (ion exchanger) for the secondary effluent of human excrement containing a high phosphate concentration. HTAL indicated stable and high phosphate removal capacity (50.8mg-P/L) in the range of ~ 5.5 of pH. The adsorption isotherm was expressed by a modified Langmuir equation. The co-existing Cl- or SO42- ion did not affect phosphate removal capacity of HTAL under the following conditions: _ 1,000 mg-Cl/L and _200mg-S/L, respectively. The effects of inorganic carbon (bicarbonate and carbonate ions) were relatively larger, and were significant in the case of the treatment of actual effluent from human excrement treatment facilities.
Organic matter and/or color in the actual effluent from a human excrement treatment facility were also effectively adsorbed on HTAL. From these results it has become clear that HTAL is applicable material for phosphate removal in the human excrement treatment processes.

Key words: human excrement, hydrotalcite compound, absorption, phosphorus removal, co-existing ion