Michael A. Heitkamp

Effects of Oxygen-Releasing Materials on Aerobic Bacterial Degradation Processes

Abstract The aerobic microbial degradation of p-nitrophenol (PNP) and phenol was examined under oxygen-limiting conditions in the presence of three known oxygen-releasing materials: (1) polyvinylidene chloride-encapsulated sodium percarbonate; (2) REGENESIS oxygen-releasing compound (magnesium peroxide); and (3) PermeOx® solid peroxygen (calcium peroxide). The degradation of PNP or phenol in buffered solutions was measured in 40-mL reaction chambers containing 25 to 300 mg of oxygen-releasing materials in the presence of immobilized chemical-degrading bacteria. Radiometric studies were used to determine total chemical mineralization and material balances of 14C-residues. Degradation of PNP and phenol increased in proportion to both the supplemented amount and the relative oxygen content of each oxygen-releasing material. Comparison of actual to theoretical degradation, based on stoichiometry of balanced equations for mineralization, showed that chemical uptake (primary degradation) at lower concentrations...

Fate in sewage of a recombinantEscherichia coli K-12 strain used in the commercial production of bovine somatotropin

SummaryThe fate of a derivative ofEscherichia coli strain W3110G [pBGH1], a strain used for production of bovine somatotropin, was examined in semi-continuous activated sludge (SCAS) units. A nalidixic acid-resistant derivative of W3110G [pBGH1], strain LBB270 [pBGH1], was used to facilitate tracking. SCAS units (300 ml) containing municipal mixed liquor were operated on a daily cycle of 23 h aeration and 1 h settling followed by decanting of clear supernatant (175 ml) and refilling with fresh primary effluent. SCAS units were inoculated with two concentrations ofE. coli LBB270 [pBGH1] and operated for 200 h. Viable levels ofE. coli LBB270 [pBGH1] were measured daily in aerated mixed liquor and decanted supernatant. Viable counts in the mixed liquor decreased from 10000- to 100000-fold in less than 200 h. Losses ofE. coli LBB270 [pBGH1] in decanted supernatants accounted for less than 2-fold of the total losses observed in the SCAS units. TheE. coli LBB270 [pBGH1] was not evenly distributed in the mixed liquor, but became preferentially associated with the settleable floc. These results show thatE. coli LBB270 [pBGH1] was unable to survive in municipal sludge even when inoculated at concentrations greater than, or comparable to, levels of indigenous microorganisms.

Laboratory-scale evaluation of fluidized bed reactor technology for biotreatment of maleic anhydride process wastewater

Fluidized bed reactor (FBR) technology has emerged in recent years as an attractive approach for the biotreatment of chemical industry wastestreams. A laboratory-scale FBR study was conducted to investigate the feasibility of utilizing FBR technology for the biotreatment of maleic anhydride wastewater generated during manufacturing operations. The maleic anhydride wastestream contains a mixture of maleic acid, fumaric acid, phthalic acid and di-n-butylphthalate (DBP). The FBR removed >98% of chemical oxygen demand (COD) and total organic carbon (TOC) from the wastewater at a chemical loading rate of 4.86 kg of COD m−3 bed day−1. Maleic acid, fumaric acid or phthalic acid were not detected in the FBR effluent indicating removal of these diacids. Residues of DBP adsorbed to granular activated carbon (GAC) stabilized at low levels indicating that the >99% removal efficiency for DBP in the FBR resulted from microbial degradation. Solids measurements showed microbial biomass levels on the GAC ranging from 10500 to 32400 mg L−1 and effluent solids production ranged from 0.027 to 0.041 kg solids kg−1 COD treated. This laboratory-scale study demonstrated that FBR technology was highly effective for the biotreatment of the maleic anhydride wastestream and may offer several advantages over traditional activated sludge systems.

Application of Immobilized Cell Technology for Biotreatment of Industrial Waste Streams

Social and regulatory pressures are forcing industry to further reduce environmental discharges of hazardous chemicals. Monsanto, like many other companies, is focusing its waste reduction efforts in three main areas: 1) Improved process efficiency leading to less waste produced. 2) Recycling of waste chemicals and unreacted intermediates. 3) Innovative waste treatment technologies. This chapter will discuss applied research designed to evaluate the fluidized bed reactor (FBR) as one type of innovative technology for biotreatment of industrial wastes.