Evaluation of phosphorus removal from wastewater by soils in rural areas in China

Low-cost, easy-maintenance and high-efficiency decentralized wastewater treatment technologies are urgently needed in rural areas of China. Processes with high potential for phosphorus removal are of great interest. However, commonly used treatment methods often do not meet the strict criteria for removing phosphorus from rural wastewater. In order to search an economic and simple technology for phosphorus removal from the common bio-technologies effluent, seven soil types collected from different rural areas in China were investigated for their ability to remove phosphorus. X-ray diffraction (XRD) was used to analyse the mineral structure, and inductively coupled plasma optical emission spectrometer (ICP-OES) was used to analyse the geochemical composition of the soil samples. Three primary minerals - quartz, albite and montmorillonite - were clearly detected. The samples were divided into two soil types, acidic soils and alkaline soils, based on their pH values. The geochemical composition study indicated that a higher percentage of Ca and Mg occurred in alkaline soils (pH > 8) than in acidic soils (pH < 6.5).="" adsorption="" isotherms="" from="" batch="" experiments="" fitted="" the="" langmuir="" and="" freundlich="" models="" well,="" the="" maximum="" p="" adsorption="" capacities="" ranged="" from="" 0.256="" to="" 1.598="" mg="" p/g,="" indicating="" a="" high="" phosphorus="" removal="" potential="" for="" all="" of="" these="" soils.="" the="" p="" fractions="" extracted="" revealed="" that="" the="" sum="" of="" naoh-extracted="" inorganic="" p="" (naoh-pi)="" was="" the="" major="" p="" component="" in="" the="" acidic="" soils,="" and="" caco_3-bound="" phosphorus="" (ca-p)="" in="" the="" alkaline="" soils.="" dynamic="" adsorption="" simulation="" showed="" that="" these="" soils="" have="" the="" ability="" to="" remove="" phosphorus="" from="" wastewater.="">