Ecological Water Treatment System for Removal of Phosphorus and Nitrogen from Polluted Water

Abstract

Abstract. We propose that phosphorus and nitrogen can be removed from polluted water using an ecological water treatment system consisting of periphyton and fish. In the proposed system, polluted water flows through a series of vessels, and the nutrients are taken up by periphyton growing on porous screens. Algal-grazing fish feed on the periphyton and either assimilate or egest the nutrients in mucus-bound feces that settle from the water into a sediment trap. Both the fish and their feces can be harvested as nutrient sinks. In this study we examined the effects of an algal-grazing cichlid (Tilapia mossambica) and a stoneroller minnow (Campostoma anomalum) on nutrient removal by the proposed water treatment system. In two experiments using tank-mesocosms, we found that the algalgrazing fish consumed the periphyton and transferred nutrients into the fish's body tissues or the sediments. The mass of phosphorus sequestered in the nutrient sink in the body tissues of the fish was approximately equivalent to the phosphorus sink in the sediments. High removal rates for phosphorus and nitrogen suggest that the proposed ecological water treatment system may be an effective ecotechnology for removal of nutrients from polluted water.

Plant Nutrient Phytoremediation Using Duckweed

“…A monoculture of L. minor consistently removed a large amount of ammonia from stormwater while a mixture of L. minor and Spirodela polyrhiza removed the largest amount of phosphorus from stormwater within 8 weeks of treatment (Perniel et al 1998). Recently, Drenner et al (1997) have described a system for culturing periphyton on eutrophic effluents and raising fish that graze on this wastewater-grown periphyton. In this way, surplus nutrients are concentrated in fish flesh.…”

Tropical treatment wetlands dominated by free-floating macrophytes for water quality improvement in Costa Rica

“…The roots of floating aquatic plants, such as those found in the wetlands in Costa Rica, provide substrate to microbial communities and aerobic microsites in a generally anaerobic environment (Ma and Yan, 1989). Microbial communities promote nutrient assimilation by plant roots and largely aid in chemical transformations, including nitrification and denitrification (Peterson and Teal, 1996;Drenner et al, 1997;Todd et al, 2003). In addition, the plants serve as a secondary carbon source as they decompose, an important component to nitrate-nitrogen removal via denitrification (Hamersley et al, 2001).…”

Spatio-temporal dynamics of nutrients in the upper Han River basin, China

“…Excessive loading of nitrogen (N) and phosphorus (P) often results in eutrophication [1,2], impairing both the physical and biologic integrity of the fluvial systems [3][4][5]. It causes undesirable algal blooming, reduced water transparency, anaerobic hypolimnions, taste and odor problems, and increasing cost of water treatment [3].…”