6CHECK G G,WALLER D H,LEE S A, etal. The later -alflow sand -filter system for septic tank effluent treatment[J]. Water Environ Res. ,1994,66:919 -928.
7PELL M, NYBEG F. Infiltration of wastewater in a newly started pilot sand- filter system: I. Reduction of organic matter and phosphprus [ J ]. J Environ Qual, 1989,18:451 - 467.
8SCHUDEL P,BOIIER M. On site wastewater treatment with intermittent buried filters [ J ]. Water Science Tech - nology,1990,22(3/4) :93 - 100.
9E - Gomez, C · CaseUas, B - Picot etal. Elimination Processes in Sta - bilization and High - Rate Algae Pond systems [J]. War · Sci · Tech,1995,31 (12).