Respirometry studies can be used to help identify waste streams and/or process chemicals that cause inhibition of aerobic metabolism. Respirometry measures the amount of oxygen used as the terminal electron acceptor in aerobic metabolism. We have two Challenge respirometer systems in our lab.

Anaerobic metabolism is often very sensitive to inhibitory chemicals present in industrial wastewater. Anaerobic respirometry measures the amount of biogas (i.e., methane) formed during anaerobic metabolism. Anaerobic respirometry can help identify individual waste streams and process chemicals that inhibit methanogenic metabolism.

Anionic surfactants are common in surface cleaners and sanitizers. These negatively charged surfactants can cause varying degrees of process inhibition depending on the amount and types of compounds present. Using LC-MS, we can determine the amount and species of these surfactants and give a better understanding of the source and effects.

Aromatics include benzene, toluene, ethylbenzene, xylenes, and phenols. These are colored and odorous compounds found in refining wastewater and other industrial wastewater. Aromatics can be very potent inhibitors of wastewater treatment processes.

We have extensive experience in conducting batch, sequencing batch, and continuous flow reactor studies to assess the feasibility of treating new waste streams. These tests allow us to determine the long-term effects of treating a wastewater or new process chemical. While respirometry is a valuable tool for testing acute inhibition, it does not account for chronic inhibition or bioaccumulation of inhibitors. Bench scale studies are often a valuable and necessary next step for determining the treatability and long-term effects of waste streams and process chemicals.

Numerous biocides are used in industrial processes to control undesirable bacterial growth. These biocides include: Per Acetic Acid (PAA), Glutaraldehyde, 2-butoxyethanol, and Isothiazalones. Biocides interfere with bacterial metabolism and/or kill the bacteria and reduce overall wastewater treatment process performance. We can measure these compounds in wastewater and assist in identifying the sources of these biocides and means of reducing their effects.

Chelators complex heavy metals and are commonly used in many industries. They can have a significant effect on biological wastewater treatment performance. We can measure many of the common chelators using HPLC.

Free Quaternary Ammonium surfactants are much more inhibitory than the bound version. Unlike the available colorimetric tests, we can distinguish between free and total quaternary ammonium surfactants using LC-MS.

Using ICP-OES we can determine the concentrations of numerous micronutrients including: Ag, Al , As , Ba, Be, B, Ca, Cd, Cr, Co, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, Pb, Sb, Se, Si, Sn, Sr, Ti, V, Zn. Many of these are essential biological nutrients at the part per billion level. If too little of these elements are present they may slow down biological metabolism and reduce process performance. Alternatively, many of these are inhibitory in the parts per million level. We can help assure that the proper levels of these metals are maintained for good process performance.

Nitrifiers are slow growing and very sensitive to a wide array of inhibitory chemicals. Nitrification Inhibition testing can help identify waste streams and process chemicals that cause problems for nitrification processes. There are two distinct populations that play an active role in nitrification; Ammonia Oxidizing Bacteria (AOBs) and Nitrite Oxidizing Bacteria (NOBs). The NOBs are often more sensitive to inhibitors than the AOBs, resulting in the accumulation of nitrite in the process. This is often called nitrite lock. Our testing can help identify potential causes of nitrite lock and nitrification failure.

These compounds can reduce surface tension, attach to negatively charged surfaces (including microorganisms), denature proteins of bacterial or fungi cells, interfere with metabolic reactions of the cell, damage/disrupt cell membranes, cause cell lysis/cell death, and cause uncoupling. Our testing can tell how many and what species of quaternary ammonium surfactants are present in the process and allow better understanding of their sources and effects.

Reduced sulfur compounds are volatile organic compounds that contain one or more reduced sulfur group. We measure RSH compounds using a gas chromatograph with a flame photometric detector. These compounds are a source of odors and indicate the presence of anoxic conditions upstream of the sampling point.

Resin acids are metabolic inhbitors found in pulp and paper wastewater. Resin acids determined by GC-MS include: abietic, palustric, dehydroabietic, dehydroabietic, dihydropalustric, , pimaric, and isopimaric acids.

Sizing agents can cause uncoupling and inhibition of metabolism and make biological floc very hydrophobic. Using GC-MS we can measure: Alkyl ketene dimers (AKD) Alkyl Succinic Anhydrides (ASA), and Urea-formaldehyde Resins (UFR).

Terpenes are metabolic inhibitors, uncoupling, and surface-active agents found in pulp and paper mill and lumber wastewaters. Using GC-MS we can measure: a- pinene , Camphene, b – mycene, b -pinene , a – terpenine , d- limonene , p- cymene , terpinolene, linolool, b –caryophyllene, borneol, stilbene, and fenchol.