The effect of water hardness on nitrilotriacetate removal and microbial acclimation in activated sludge

The mineralization of 1.0 to 100 ng each of four complexing compounds-oxalate, citrate, nitrilotriacetate (NTA), and EDTA-per ml was tested in media prepared in accordance with equilibrium calculations by a computer program so that the H, Ca, Mg, Fe, or Al complex (chemical species) was predominant. Sewage microorganisms mineralized calcium citrate more rapidly than iron, aluminum, or hydrogen citrate, and magnesium citrate was degraded slowest. Aluminum, hydrogen, and iron oxalates were mineralized more rapidly than calcium oxalate, and magnesium oxalate was decomposed slowest. Sewage microorganisms mineralized calcium NTA but not aluminum, magnesium, hydrogen, or iron NTA or any of the EDTA complexes. Pseudomonas sp. mineralized calcium and iron citrates but had no activity on hydrogen, aluminum, or magnesium citrate. Pseudomonas pseudoalcaligenes mineralized calcium, iron, hydrogen, and aluminum citrates but had little activity on magnesium citrate. Pseudomonas alcaligenes used calcium, iron, hydrogen, and aluminum oxalates readily, but it used magnesium oxalate at a slower rate. Listeria sp. destroyed calcium NTA but had no effect on hydrogen, iron, or magnesium NTA. Increasing the Ca concentration in the medium enhanced the breakdown of NTA by Listeria sp. The different activities of the bacterial isolates were not a result of the toxicity of the complexes or the lack of availability of a nutrient element. NTA mineralization was not enhanced by the addition of Ca to Beebe Lake water, but it was enhanced when Ca and an NTA-degrading inoculum were added to water from an oligotrophic lake. The data show that chemical speciation influences the mineralization of organic compounds by naturally occurring microbial communities and by individual bacterial populations.

Section: Hours Hoursmentioning

confidence: 99%

Effects of Chemical Speciation on the Mineralization of Organic Compounds by Microorganisms

Madsen

Alexander

1985

“…The time for small populations of mineralizing organisms to become sufficiently large to bring about a detectable loss of the chemical has also been cited as an explanation for acclimation (17,24). Other possible explanations include an insufficient supply of inorganic nutrients (11,23), the preferential utilization of other organic compounds before the chemical of interest (10,11), the time needed for the mineralizing species to acclimate to toxins or for inhibitors that are present in the environment to be destroyed, or predation by protozoa on the mineralizing organisms.…”

mentioning

confidence: 99%

Explanations for the acclimation period preceding the mineralization of organic chemicals in aquatic environments

Wiggins¹,

Jones²,

Alexander³

1987

170

A study was conducted of possible reasons for acclimation of microbial communities to the mineralization of organic compounds in lake water and sewage. The acclimation period for the mineralization of 2 ng of p-nitrophenol (PNP) or 2,4-dichlorophenoxyacetic acid per ml of sewage was eliminated when the sewage was incubated for 9 or 16 days, respectively, with no added substrate. The acclimation period for the mineralization of 2 ng but not 200 ng or 2 ,ug of PNP per ml was eliminated when the compound was added to lake water that had been first incubated in the laboratory. Mineralization of PNP by Flavobacterium sp. was detected within 7 h at concentrations of 20 ng/ml to 2 ,ug/ml but only after 25 h at 2 ng/ml. PNP-utilizing organisms began to multiply logarithmically after 1 day in lake water amended with 2 ,ug of PNP per ml, but substrate disappearance was only detected at 8 days, at which time the numbers were approaching 105 cells per ml. The addition of inorganic nutrients reduced the length of the acclimation period from 6 to 3 days in sewage and from 6 days to 1 day in lake water. The prior degradation of natural organic materials in the sewage and lake water had no effect on the acclimation period for the mineralization of PNP, and naturally occurring inhibitors that might delay the mineralization were not present. The length of the acclimation phase for the mineralization of 2 ng of PNP per ml was shortened when the protozoa in sewage were suppressed by eucaryotic inhibitors, but it was unaffected or increased if the inhibitors were added to lake water. We suggest that the time for enzyme induction, mutation, diauxie, and the presence of toxins are not the causes of the acclimation period for PNP mineralization in aquatic environments but rather that the acclimation period largely reflects the time for multiplication of the initially small population of active organisms. That time may be further extended by a limiting supply of inorganic nutrients in lake water or by predation by protozoa in sewage.

“…Atlas and Bartha (1) suggested that the low concentrations of N and P in seawater limit the growth of bacteria that degrade petroleum. Vashon et al (15) observed that the acclimation period for mineralization of nitrilotriacetic acid is shorter in waters in which the concentrations of such cations as Ca and Mg are high than in waters containing low concentrations of the cations. Zaidi et al (16) suggested that bacteria are affected by ion imbalance during the degradation of organic compounds at low concentrations.…”

Section: Discussionmentioning

confidence: 99%

Influence of Calcium, Iron, and pH on Phosphate Availability for Microbial Mineralization of Organic Chemicals

Robertson

Alexander

1992

A study was conducted to determine some of the factors affecting the P requirement for the biodegradation of p-nitrophenol, phenol, and glucose by Pseudomonas and Corynebacterium strains. Mineralization of glucose was rapid and the Pseudomonas sp. grew extensively in solutions with 5 and 10 mM phosphate, but the rate and extent of degradation were low and the bacterial population never became abundant in media with 0.2 mM phosphate. Similar results were obtained with the Corynebacterium sp. growing in media containing p-nitrophenol or phenol and in solutions with a purified phosphate salt. The extent of growth of the Corynebacterium sp. was reduced with 2 or 10 mM phosphate in media containing high Fe concentrations. Ca at 5 mM but not 0.5 mM inhibited p-nitrophenol mineralization by the Corynebacterium sp. with phosphate concentrations from 0.2 to 5.0 mM. Phenol mineralization by the Pseudomonas sp. in medium with 0.2 mM phosphate was rapid at pH 5.2, but the bacteria had little or no activity at pH 8.0. In contrast, the activity was greater at pH 8.0 than at pH 5.2 when the culture contained 10 mM phosphate. These effects of pH were similar in media with 5 mM Ca or no added Ca. We conclude that the effect of P on bacterial degradation can be influenced by the pH and the concentrations of Fe and Ca.