Research laboratory wastewater neutralization systems

Abstract

Laboratory wastewater neutralization systems are increasingly being specified for academic teaching and research buildings by many environmental consultants and design engineers. While real efforts to improve the quality of wastewater are generally positive, simply installing such systems without regard to their operational setting increases capital costs, significantly increases equipment service and maintenance needs and expenses, and can potentially generate higher environmental, health, and safety risks from chemical handling exposures, spills, leaks, or uncontrolled releases to sewer. In response to concerns about possible neutralization system needs for a new chemistry building at Yale University, continuous pH measurements were collected from several laboratory-intensive teaching and research buildings over periods of time ranging from 22 to 37 days in each building. Real-time pH measurements were collected in the main branch of the laboratory wastewater drain line in each building just prior to junction with house sanitary lines. Laboratory wastewaters averaged 6.5 pH units over the aggregate datalogged period of 82 days during the academic year. While more extreme pH values were occasionally observed, values less than about 5 or greater than about 9 were exceedingly rare, and accounted for fewer than 15 minutes of the laboratory wastewater discharged during the nearly 3 months of continuous sampling. Since the measurements were all collected at points just prior to mixing with building sanitary effluent, significant additional wastewater dilution occurred prior to final discharge to sewer. Based upon these results and a review of the potential health and safety hazards associated with neutralization systems, their installation – at least in academic teaching and research laboratories – is generally unnecessary.