Toxicity Studies of AKGA/Hydrazines Degradation By-Products and Their Compatibility with Sewage Treatment Plant Operation

Abstract

A new method to treat hydrazine and monomethylhydrazine (MMH) using a-ketoglutaric acid (AKGA) was proposed. From the reaction of AKGA with hydrazine or MMH, two stable products are formed, 1,4,5,6-tetrahydro-6-oxo-3-pyridazinecarboxylic acid (PCA) and 1-methyl-1,4,5,6-tetrahydro-6-oxo-3-pyridazinecarboxylic acid (mPCA), respectively. With a focus toward use at an industrial facility, tests were undertaken to determine whether waste streams produced from this reaction can be metered into a municipal wastewater facility for final disposal. PCA and mPCA were analyzed for acute toxicity using crustaceans (Ceriodaphnia dubia) and fish (Pimephales promelas) and their effect on the wastewater treatment efficiency and viability using activated sludge (AS) microbes, and their biodegradability by AS organisms. Acute toxicity on crustaceans and fish was investigated according to the methods for acute toxicity by USEPA Method EPA-821-R-02-012. The effect of mPCA and PCA in the treatment efficiency and viability were estimated from respiration inhibition tests (USEPA, 2012) and heterotrophic plate counts. Last, the biodegradability of PCA and mPCA was assessed using the Closed Bottle Method. The results of this study showed that mPCA is significantly more toxic to C. dubia and P. promelas than PCA at the high concentrations ranges used in this study (0.5-1.5 g/L). On the other hand, PCA and mPCA did not show a significant inhibition of carbonaceous respiration of AS microbes at concentrations ranging from 0.5 to 1.5 g/L, although both exhibited some inhibitory effects on nitrification. Under the conditions of this study, PCA was biodegradable by AS while mPCA was not.

Photoelectrochemical generation of hydrogen and electricity from hydrazine hydrate using BiVO4 electrodes

“…For example, Kennedy Space Center (KSC) produces several thousand gallons of diluted hydrazine waste per year. 9 Significant amounts of methylhydrazine/hydrazine were found in National Aeronautics and Space Administration (NASA) wastewater. 10 On the other hand, the toxicity of hydrazine can be reduced by using harmless hydrazone or hydrazide, which releases hydrazine hydrate in contact with a solvent.…”