Coal Conversion Effluents Research Articles

Decolorization of phenolic effluents by soluble and immobilized phenol oxidases

Colour removal from phenplic industrial effluents by phenol oxidase enzymes and white-rot fungi was compared. Soluble laccase and horseradish peroxidase (HRP) removed colour from pulp mill (E), cotton mill hydroxide (OH) and cotton mill sulphide (S) effluents, but rapid and irreversible enzyme inactivation took place. Entrapment of laccase in alginate beads improved decolorization by factors of 3.5 (OH) and 2 (E); entrapment of HRP improved decolorization by 36 (OH), 20 (E) and 9 (S). Beads were unsuitable for continuous use because the enzymes were rapidly released into solution. Co-polymerization of laccase or HRP with L-tyrosine gave insoluble polymers with enzyme activity. Entrapment of the co-polymers in gel beads further increased the efficiency of decolorization of E by 28 (laccase) and by 132 (HRP) compared with soluble enzymes. Maximum decolorization of all three effluents by batch cultures of Coriolus versicolor (70%–80% in 8 days) was greater than the maximum enzymic decolorization (48% of OH in 3 days by entrapped laccase). Soluble laccase (222 units ml−1) precipitated 1.2 g l−1 phenol from artificial coal conversion effluent at pH 6.0 and the rate of precipitation and enzyme inactivation was faster at pH 6.0 than at pH 8.5.

Anodic oxidation of phenolics found in coal conversion effluents

AbstractSolutions of phenol, o‐cresol, p‐cresol, 2,3‐xylcnol, 3,4‐xylenol, resorcinol, and catechol at concentrations below I g/L were oxidized at constant current on a packed bed lead dioxide electrode with electrolyte recirculation. The effects of applied current and initial concentration on the extent of oxidation with time were explored. The observed ranking in ease of oxidation was phenol > 2,3‐xylenol > resorcinol > p‐cresol > 3,4‐xylenol > o‐cresol. Although the phenolics were largely destroyed, organic degradation products of the quinone and hydroquinone type remained in solution. A mixture of five monohydric phenols showed 96% destruction of phenolics, a 50% reduction in B.O.D. but a reduction in total organic carbon of only 22%.

Methanogenesis in freshwater sediments: inherent variability and effects of environmental contaminants.

Temporal and spatial variability of methanogenesis and the effects of environmental contamination on methanogenesis were examined in freshwater sediments. Temporal and spatial variation was found to be significant in uncontaminated freshwater reservoir sediments. The relative concentration of organic matter and temperature explained approximately 43% of the total variability. Known environmental contaminants marginally inhibited methanogenesis and only a coal conversion effluent and phenanthrene, 100 mg L-1, demonstrated statistically significant inhibition of methanogenesis under acute dosing conditions. Methyl viologen, a potent inhibitor of pure culture methanogenesis, inhibited sediment methanogenesis at high concentrations, i.e., 2570 mg L-1, indicating that the sediment environment protected the methanogenic population from the toxic effects of the environmental contaminants.

A reevaluation of the toxicity of coal conversion process waters.

The acute toxicity to Daphnia magna of both untreated and treated process waters from a hydrocarbonization (HCZ) coal conversion process was evaluated recently by PARKHURST et al. (1979). Phenol, ammonia, and the three cresol isomers displayed additive toxicity in the untreated HCZ effluent. However, the treated HCZ effluent, in which concentrations of ammonia, phenol, and the cresols were reduced by biological oxidation, was much less toxic than might have been predicted from the concentrations of the individual components. At the LC50 dilution for the treated HCZ effluent, the concentration of total ammonia present was more than three times the LC50 value for D. maqna. This indicated a less-than-additive ammonia toxicity ~dT-6~--antagonistic interactions among ammonia and the other constituents. The less-than-additive ammonia toxicity was calculated from total ammonia concentrations and was attributed by PARKHURST et al. to a lower pH in the treated HCZ effluent than in a separate ammonia toxicity bioassay. But total ammonia includes both un-ionized ammonia (NH3) and ionized ammonia (NH4 +) in a pH- and temperature-dependent equilibrium. Un-ionized NH 3 is toxic to many aquatic organisms while NH4 + is relatively nontoxic (MCKEE and WOLF 1963). Therefore, if D__ L. magna are indeed more sensitive to NH 3 than to NH4 +, PARKHURST et al. incorrectly calculated the contribution of ammonia to the HCZ effluent toxicities by using total ammonia rather than un-ionized ammonia concentrations. Their interpretations of the importance of ammonia in these HCZ effluents may, therefore, be misleading and are reevaluated in the present report. The purposes of this paper are (1) to clarify the role of ammonia in the toxicity of complex coal conversion wastewaters, (2) to reevaluate the toxic contribution of ammonia in the treated HCZ effluent, and (3) to compare these results with literature reports for other coal conversion effluents (DEGRAEVE et al. 1980, HERBERT 1962). For the U.S. Department of Energy's Hanna-3 underground coal gasification (UCG) condenser water, DEGRAEVE et al. evaluated the interaction of phenol and ammonia in the toxicity of this process water to aquatic biota. Similarly, HERBERT determined the toxic contributions of phenol and ammonia in spent coal distillation process liquors to rainbow trout.

Biological Treatment of Synthetic Fuel Wastewater

A wastewater biological treatability study was performed with effluent from the Grand Forks Energy Technology Center slagging fixed-bed coal gasification process. It was found that ammonia stripped wastewater could be processed reliably at 33% strength at substrate removal rates less than approximately 0.6 mg COD removed/mg MLVSS-day. The wastewater when diluted to 33% strength contained highest reported concentration of organic contaminants in coal conversion effluents processed successfully by air activated sludge. The bacterial yield coefficient for treatment of 33% strength stripped wastewater was 0.29 (COD basis) and the endogenous respiration rate coefficient was 0.038 day\u-¹ (COD basis). Raw wastewater with no ammonia removed could be processed at 40% strength. Nitrification was feasible with both stripped and unstripped wastewater. COD removal rates which impaired nitrification were dependent on ammonia loading, as nitrification could be sustained at higher values of substrate rate with unstripped wastewater than was observed with stripped wastewater.

Toxicity of underground coal gasification condenser water and selected constituents to aquatic biota.

The acute and embryo-larval toxicity of the Laramie Energy Technology Center's Hanna-3 underground coal gasification (UCG) condenser water and its constituents were studied in continuous-flow bioassays. The 96-hr LC50 dilution values for untreated Hanna-3 UCG condenser water were 0.1% for rainbow trout, 0.11% for fathead minnows and the 48-hr LC50 dilution forDaphnia pulicaria was 0.18%. Separate 96-hr acute tests with phenol, ammonia, and ammonia plus phenol showed that these two constituents, acting synergistically, were the major constituents affecting the acute toxicity of this coal conversion effluent to fishDaphnia pulicaria, on the other hand, was relatively insensitive to phenol exposure; the primary constituent of Hanna-3 UCG condenser water affecting this species was ammonia.

An evaluation of the acute toxicity to aquatic biota of a coal conversion effluent and its major components.

This paper describes a systematic evaluation of the potential acute toxicity to aquatic organisms of aqueous wastes from a coal conversion process. We discuss how the information gained can be used to anticipate evnironmental problems arising from this new technology before it is implemented on a large commercial scale.

Reduced toxicity of an aqueous coal-conversion effluent following waste disposal treatment.

The Solvent Refined Coal process, which produces fuel low in sulfur and ash from coals high in these substances, gives rise to a wastewater with a high pH value and high contents of sulfur, phenol, and cresols, but treatment of the wastewater in an ''oxycontact'' bioreactor followed by sand and carbon filtration has been shown to be feasible. Experiments carried out to assess the toxicity of the treated waste to an aquatic organism.

Structure-toxicity correlations of organic contaminants in aqueous coal-conversion effluents.

Five series of organic contaminants associated with aqueous coalconversion effluents were studied to determine the correlation between their known partition coefficients in the octanol-water system and their toxicity to the ciliateTetrahymena pyriformis. In all five series, toxicity increased and solubility decreased with increased alkyl substitution. Compounds containing the equivalent of two or more methyl groups are more toxic than those with one or no alkyl substitutions.

Toxic interaction of mixtures of two coal conversion effluent components (resorcinol and 6-methylquinoline) to Daphnia magna.

Acute toxicities of mixtures of resorcinol and 6-methylquinoline to Daphnia Magna (a representative zooplankter) were investigated to assist in assessing the potential effects of coal conversion effluents on aquatic biota. Results indicated that mixtures of resorcinol and 6-methylquinoline were less toxic than either pure compound tested alone. The data suggest that antagonism occurs when resorcinol is the major toxic component, while an infra-additive interaction occurs when 6-methylquinoline is the major toxic component. The work indicates that addition of fractional toxicities may produce substantial errors in prediction of toxicity of mixtures of non-homologous organic components. (CAJ)