A 1-year study has been completed to evaluate use nf artificial marshes as a teatment system for waste from confined hog feeding operatiuns, A 3 x 2 factor ial experimental design was employed to evaluate the performance of marshes planted with one of three emergent species (Sparganium eurycarpum Phragniites austi:alis, glauca)and receiving three different loadings of hog waste. Each treatment was replicated twice, For each marsh, a complete hydrological and nutrient (N, P) budget was deter­ mined. Data on COD and solids were also collected. The growth of the plants, particularly rates of vegetative reproduction, were also monitored regularly throughout the growing season to examine the effect of sludge accumulation on plant vigor. Because the odor associated with present animal waste handling systems has been a major problem, the most important feature of artificial marshes treating hog waste is that they seem not to have developed any odors during their first year of operation . Emergent plants have a system of inter­nal air spaces that allows oxygen from the leaves to diffuse into the rhizomes and roots, Enough oxygen seems to be diffusing out of the roots and into the accumulating sludge to prevent it from becoming completely anaerobic.

During the summer of 1977, the marshes produced a superior effluent to that of an anaerobic lagoon. Up to 70% of the TVS and 50% nf the COD waa re­ moved by the marshes, largely through meuhanical filtration. Approximately 17% of the N and P was removed, mostly by uptake into the plants.

Design criteria for these marshes and suggested modifications are pre­sented.