Impact of heat-treatment on wastewater analytical parameters.

Raw wastewater analysis is an important step in treatment assessment; however, it is associated with risks of personnel exposure to pathogens. Such risks are enhanced during virus outbreaks, such as the COVID pandemic, and heat-treatment is a commonly used mitigation measure. We examined whether heat-treatment compromises wastewater analytical parameters results. We found that heat-treatment of blackwater at 60 °C for 90 min in capped containers yielded no statistically different values (p > 0.05) for pH, chemical oxygen demand (COD), ammonia (NH3), total nitrogen (TN), total suspended solids (TSS), and turbidity for specimens from three different sources. This heat-treatment inactivated coliform bacteria (>4 log10 reduction) thus compromising the measurement of commonly used fecal contamination indicators. The observation of intact helminth eggs in heat-treated specimens suggests that the helminth egg enumeration assay is not compromised. These findings indicate that heat-treatment for the safe handling of wastewater, as may be needed in future virus outbreaks, does not affect the measurements of many common wastewater physico-chemical properties.

Potential Pitfalls in Wastewater Phosphorus Analysis and How to Avoid Them.

Due to the increasing adoption of nutrient discharge regulations, many research groups are stepping into new territory with phosphorus (P) measurements. Accurate reporting of P concentrations in effluent from novel wastewater treatment technologies is critical for protecting both environmental and human health. Analysis of P in wastewater is prone to pitfalls because of the (1) variety of chemical forms of P in wastewater (orthophosphate, condensed P, and organic P), (2) availability of different chemical assays for measuring different P forms, and (3) different conventions in the units for reporting P. Here, we present a case study highlighting how these pitfalls affect analysis and interpretation of P measurements. We show that, when used appropriately, commercially-available kits are indeed accurate tools for evaluating reactive P and total P concentrations. For both standard solutions and real wastewater, we systematically remove steps from the total P protocol to show how protocol deviations affect the results. While standard solutions are important for validating analytical methods, commercially-available wastewater standard solutions only contain P as orthophosphate (reactive P). We therefore demonstrate options for making a mixed-P standard solution containing acid-hydrolyzable and/or organic P compounds that can be used to validate both reactive P and total P assays.