FATE OF GLUCOSE IN SOIL USED TO TREAT WASTEWATER (KINETICS, UPTAKE, COD (CHEMICAL OXYGEN DEMAND))

PETER N COODY, Purdue University

Abstract

Land treatment of a glucose-rich solution simulating wastewater from the corn processing industry was studied under laboratory conditions. Objectives were to quantify the effects of glucose-C on covercrop performance and soil properties, and to define glucose uptake kinetics by soil microorganisms. A synthetic wastewater consisting of glucose dissolved in a plant nutrient solution was added to soil columns with and without a covercrop of reed canarygrass (Phalaris arundinacea L.) to provide a chemical oxygen demand (COD) of 0 to 180 mmol O(,2) column('-1) week('-1) (i.e., 0 to 0.22 Mmol O(,2) ha('-1) week('-1)). The columns were treated with glucose for 25 weeks and were monitored for soil gases, plant yields, water use, and COD removal. Additions of COD increased CO(,2) concentrations in the soil atmosphere to over 480 times atmospheric levels. This coincided with a depletion of O(,2) in the soil, but anaerobic conditions were not observed to a depth of 25 cm. Total plant yields were inversely proportional to COD loading, ranging from 20.3 to 2.8 g column('-1) (25.0 to 3.4 Mg ha('-1)) over the 25 week period. Water use was related to yields in the cropped columns but remained unaffected by COD loading in the uncropped columns. Greater than 96% of the added COD was removed in all columns. Experiments conducted to describe glucose uptake kinetics in soil utilized a sandy soil amended with UL('-14)C glucose dissolved in an inorganic nutrient solution to provide concentrations of 2.5, 5.0, 10.0, and 20.0 mmol glucose L('-1) in the soil solution. The soils were incubated at 4, 12, or 25(DEGREES)C and the soil was periodically analyzed for glucose, soluble ('14)C, and organic ('14)C; ('14)CO(,2) evolved was also measured. A detailed C balance developed for each temperature provided sufficient data to define Michaelis-Menten kinetic parameters for glucose uptake and metabolism. V(,max) values ranged from 0.12 to 1.61 mmol hr('-1) L('-1) and were proportional to temperature. This temperature effect followed Arrhenius theory, providing an activation energy of 20.57 Kcal mol('-1). Depletion of glucose and soluble ('14)C was nearly identical at 12 or 25(DEGREES)C, but glucose was removed approximately 3.5 times faster than soluble ('14)C at 4(DEGREES)C.

Degree

Ph.D.

Subject Area

Agronomy

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