Phytoremediation of Anaerobic Digester Effluent for Water Purification and Production of Animal Feed
Titel:
Phytoremediation of Anaerobic Digester Effluent for Water Purification and Production of Animal Feed
Auteur:
A. E. Ghaly
Verschenen in:
American journal of agricultural and biological science
Paginering:
Jaargang 2 (2007) nr. 1 pagina's 1-14
Jaar:
2007
Inhoud:
The application of phytoremediation for purification of an anaerobically treated dairymanure and production of forage crops was investigated. Four crops (two cereals and two grasses)were examined for their ability to grow hydroponically and to remove pollutants (nutrients) from dairywastewater. The preliminary experiments showed that timothygrass and orchardgrass did not performwell as aquatic plants. Only 24 and 29% of the seeds germinated after 19-21 days giving a crop yieldof 21 and 19 t ha¯1 for timotygrass and orchardgrass, respectively. Wheat and barley grow very well asaquatic plants with a seed germination of 83 and 73 (in 7 days) and a crop yield of 106 and 86 t ha¯1 forwheat and barley, respectively. The effect of light duration, seeding rate, wastewater application rateand fungicidal treatment on the wheat crop yield and pollution potential reduction were studied. Theresults indicated that with this system, a wheat forage crop could be produced in 21 days fromgermination to harvest. A treatment combination of wastewater application rate of 900 mL day¯1, aseeding rate of 400 g and a light duration of 12 hrs gave the best results for crop yield (3.81 kg ofwheat tray¯1). Based on thirteen harvests per year, a total possible yield of 3300 t ha¯1 per year can beachieved with the system. This is more than 102 times grater than the yield obtainable from a filedgrown conventional forage of 245 t ha¯1 per year. Wheat had a superior nutritional value (higherdigestible energy, higher carbohydrates, fat, protein and mineral contents and less crude fiber)compared to the other field forage crops. It also contained higher macro and micro nutrients (Sodium,Magnesium, Manganese, Iron, Copper, Boron, Selenium, Iodine and Cobalt) than field forage crops.Removal efficiencies of 72.4, 88.6 and 60.8 % can be achieved for the total solids, Chemical OxygenDemand (COD) and ammonium nitrogen, respectively. A nitrate nitrogen concentration of 7.1 mg L¯1was also found in the effluent from the hydroponic system. This is below the Canadian Environmentaland Health Guidelines of 10 mg L¯1.
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