Microorganisms and Higher Plants for Waste Water Treatment

Abstract

AbstractBatch experiments were conducted to compare the waste water treatment efficiencies of plant‐free microbial filters with filters supporting the growth of reeds (Phragmites communis), cattail (Typha latifolia), rush (Juncus effusus), and bamboo (Bambusa multiplex). The experimental systems consisted of two components in series. The first component was an anaerobic settling‐digestion container. The second was a “nonaerated” trough filled with rocks, decreasing from large rocks (up to 7.5‐cm diam) at the bottom, to pea gravel (0.25‐ to 1.3‐cm diam) at the top. The plant‐free microbial filter was equally effective in carbonaceous BOD5 (5‐d biochemical O2 demand) removal. The vascular aquatic plant series enhanced ammonia removal, and consequently improved nitrogenous BOD5 removal. Under the conditions of these experiments, raw sewage with initial BOD5's of 100 mg/L can be upgraded to meet secondary standards with 6 h in component 1, and 6 h in a plant‐free filter or filter using cattail, rush, or reed. When initial BOD5's are approximately 450 mg/L, 24 h in component 1, 29 h in a reed filter are required to meet secondary standards. Total N removal studies were conducted, which demonstrated that a reed system is capable of removing NO3‐N and NH3‐N simultaneously, probably through a common NO2‐N intermediary, then to N2. Overall, the reed system was superior to all others evaluated in this research project.