BOD Determination, Cleaning Solution Preparation, and Waste Disposal in Laboratories

Abstract

Under the sponsorship of the Water Environment Federation, simplified laboratory procedures for biochemical oxygen demand (BOD) determination as outlined in the APHA/AWWA/WPCF Standard Methods for the Examination of Water and Wastewater were developed for use by the waste treatment plant operators, researchers, and engineers. The step-by-step, simplified BOD testing procedures with or without seeding have been documented. All BOD bottles and other glassware must be thoroughly cleaned before and after testing. Some highly toxic, hazardous wastewaters are generated from BOD testing in the laboratory. These wastes must be either pretreated for sewer discharge or stored and delivered to a licensed hazardous waste handler for further processing. This chapter discusses a laboratory manager's decision process for waste management and preparation methods and disposal processes of various cleaning solutions, such as dichromate acid (chromatic acid), hydrochloric acid, sulfuric acid, nitric acid, Piranha solution, fuming sulfuric acid solution and Nochromix solution. Dichromate acid cleaning solution is used when the generated waste contains toxic chromium (VI) and chromium (III). A special process system consisting of oxidation– reduction, neutralization, precipitation, and filtration may be used by a BOD testing laboratory for successful treatment of chromium-containing waste, if the laboratory is a government-approved small quantity generator. Otherwise, the waste must be stored and hauled away for off-site treatment by a commercial hazardous waste handler. When an alternative cleaning solution containing no hazardous heavy metals is used for BOD bottles and glassware cleaning, the resulting BOD testing wastewater can be easily pretreated by an elementary neutralization process prior to sewer discharge, again, if the laboratory is an approved small quantity generator.