INVESTIGATION OF SOIL TREATMENT SYSTEMS FOR SEPTIC TANK EFFLUENT. III. THE FATE OF PHOSPHORUS

Eight sand filter systems and eight infiltration systems were investigated for the fate of phosphorus (P). All of the systems have been in use for several years. The soil from the systems was extracted by different methods by use of extractants, e.g. HC1, a mixture of acetic acid and ammoniumlactate (AL-solution) and water. The sorbed P was fractionated according to a modified Chang and Jackson method. The desorption of P was measured in 0.01 M CaCl2. Generally the highest amounts of extractable P were found just beneath the distribution pipe. Differences along the pipe in the systems and between the locations can at least partly be explained by differences in the design of the systems, including the design of the perforated distribution pipe, the slope of the pipe and the loading of the system. The extractable amounts of P are not very well correlated with a single soil parameter. Extractable Al and/or Fe were, however, always represented among the three parameters which gave highest reduction in the variance of extractable P. “Complete abstract not presented.”