6Bonomo L, Pastorelli G, Zambon N. Adwantages and limitations of duckweedbased wastewater treatment systems[J]. Wat Sci and Tech, 1997,35(5) :239 -246.
7Frassinetti P, Catunda C, van Haandel A C. Improved performance and increased applicability of waste stabilization ponds by pretreat- ment in a UASB reactor [ J ]. Wat Sci Tech, 1996,33 (7) : 147 - 156.
10Sopper W E, Kardos L T. Recycling tread municipal wastewater and sludge through forest and cropland [ M ]. University Park, Pennsylva- nia: Pennsylvania State University Press, 1973:31 - 35.