Transport and degradation of propylene glycol in the vadose zone: model development and sensitivity analysis

Schotanus, D.; Meeussen, J.C.L.; Lissner, Heidi; Ploeg, Martine van der; Wehrer, Markus; Totsche, Kai Uwe; Zee, S.E.A.T.M. van der

doi:10.1007/s11356-013-2033-y

Cited by 6 publications

(4 citation statements)

References 34 publications

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“…Methanol and EG are the most toxic additives, with an oral chronic reference dose (RfD) of 2 mg/day per kg of weight, whereas PG is far less toxic (RfD = 20 mg/kg/day) [9]. Organic additives have a possible indirect impact represented by the redox alteration of groundwater, which may trigger the mobilization of heavy metals [10], as observed in several airports where these compounds are used as deicing agents [11,12]. On the other hand, calcium chloride has a negligible toxicity [13] and no groundwater potential chemical impact (in the case of a release into subsurface) other than an increase of Ca 2+ and Cl − ions.…”

Section: Introductionmentioning

confidence: 99%

Environmental and Economic Impact of the Antifreeze Agents in Geothermal Heat Exchangers

et al. 2020

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Borehole heat exchangers (BHEs) generally employ water-antifreeze solutions to allow working fluid temperatures to fall below 0 °C. However, some local regulations have forbidden antifreeze additives (even non-toxic ones) to avoid groundwater pollution in case of pipe leakage. This paper presents a techno-economic and environmental analysis of four different fluids: propylene glycol at 25% and 33% weight concentrations, calcium chloride at 20% weight concentration (CaCl2 20%), and pure water. Thermal loads from 36 case studies in six different climate zones are used to perform BHE sizing and compare the abovementioned fluids from the economic, operational, and environmental points of view. The economic analysis and the carbon footprint assessment are performed on a life cycle of 25 years considering the installation (BHE drilling, fluid) and operation (heat pump and ground-side circulation pump energy demand, fluid replacement) of the simulated GSHPs. Results highlight that using pure water as a heat carrier fluid is convenient for cooling-dominated buildings but, for heating-dominated buildings, this choice leads to a noticeable increase of the BHE needed length which is not compensated by the lower operational costs. On the other hand, avoiding the use of antifreeze additives generally leads to a reduction of the lifetime carbon footprint, with a few exceptions in very cold climates. CaCl2 20% proves to be a good choice in most cases, both from the economic and the environmental points of view, as it allows a strong reduction of the installed BHE length in cold climates with a low additional cost and carbon footprint.

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Section: Introductionmentioning

confidence: 99%

Environmental and Economic Impact of the Antifreeze Agents in Geothermal Heat Exchangers

et al. 2020

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“…Consequently, Fe and Mn oxides are used as alternative electron acceptors, and reduced Mn (II) and Fe(II) species occur in the pore water (French et al 2001;Jaesche et al 2006;Lissner et al 2013;Schotanus et al 2013). The overall redox reaction for PG and FO degradation is shown in Table 1.…”

Section: Introductionmentioning

confidence: 99%

Constraints of propylene glycol degradation at low temperatures and saturated flow conditions

Lissner

Wehrer

Reinicke

et al. 2014

Environ Sci Pollut Res

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During snowmelt, the infiltration of large amounts of propylene glycol (PG), the major compound of many aircraft deicing fluids, affects redox processes and poses a contamination risk for the groundwater. To gain a better understanding about the degradation of PG and the associated biogeochemical processes under these conditions, we conducted saturated soil column experiments at 4 °C. During two successive PG pulses, we monitored the effect of the runway deicer formate (FO) and changing redox conditions on PG degradation. Furthermore, we applied first-order and simplified Monod kinetics to describe PG and FO transport. The transport of 50 mg l(-1) PG showed three stages of microbial degradation, which were defined as lag phase, aerobic phase, and anaerobic phase. During the second pulse, lag effects diminished due to the already accomplished microbial adaption, and the initial degradation rate of PG increased. Degradation of PG was most efficient during aerobic conditions (aerobic phase), while the subsequent drop of the redox potential down to -300 mV decreased the degradation rate (anaerobic phase). Formate addition decreased the overall degradation of PG by 50 and 15 % during the first and second pulse, illustrating the inhibitory effect of FO on PG degradation. The concurrent increase of Fe(III), organic carbon, and the turbidity in the column effluent after PG and FO application suggest the combined export of Fe adsorbed to fragments of detached biofilm. Neither the first-order nor the simplified Monod model was able to reconstruct the dynamic breakthrough of 50 mg l(-1) PG. The breakthrough of 1,000 mg l(-1), however, was described reasonably well with first-order kinetics. At low temperature and high water saturation, the application of first-order degradation kinetics seems therefore appropriate to describe the transport of high concentrations of PG.

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“…Aerobic biodegradation is modelled with Monod kinetics as described by Barry (2002). Although various chemical species such as oxygen, nitrate, and manganese can act as the electron acceptor, this is with varying levels of preference (Schotanus et al, 2014), and depends on the redox potential of the soil. We focus on dissolved oxygen as the electron acceptor.…”

Section: Methodsmentioning

confidence: 99%

“…The soil type is loamy sand in the entire domain, and the associated soil hydraulic parameters are obtained from Carsel and Parish (1988). Parameters describing the biodegradation reaction are inspired by realistic values for propylene glycol -an antifreeze fluid used widely in climates that experience snowmelt infiltration (Schotanus et al, 2014). The outcomes analyzed are the biodegraded fraction 𝐹 𝑑 and the spatial Soil contaminant transport and mixing-limited biodegradation distribution of biomass growth 𝐵(𝑥, 𝑧).…”

Section: Methodsmentioning

confidence: 99%

Managed aquifer recharge with marginal water for irrigation and contaminant attenuation

Tang¹

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Managed aquifer recharge with marginal water allows for contaminants of emerging concern (CECs) to be attenuated in-situ, and for water to be more efficiently used. In phreatic aquifers underlying agricultural fields, this also increases water availability for crops. Existing drainage systems may be adapted for both injection (subirrigation) and extraction (drainage). We address subirrigation with treated domestic wastewater by considering numerical simulations and an experimental field site implemented as a proofof-concept. The transport, adsorption, and biodegradation of tracers, and relatively mobile and persistent CECs (using carbamazepine as an example), are analyzed. For this scenario, almost all non-biodegraded solutes irrigated into the soil are advected laterally towards surface water channels by regional groundwater flow. During the crop season, tracers may rise to the root zone, but only directly above irrigation drains. Accordingly, although up to 10% of tracers irrigated over four years are passively taken up by crops, this is concentrated in the plants situated directly above irrigation drains. No significant spreading of carbamazepine to the root zone occurs, and <1% of the total irrigated amount is taken up by crops after four years. Due to the annual precipitation surplus, solutes that are not very mobile are unlikely to enter the root zone even after decades of irrigation, because the length of the short-term precipitation shortage (crop season) is insufficient for them to rise to the root zone. Furthermore, carbamazepine biodegrades almost completely before being advected any significant distance from the drains. As carbamazepine is a relatively mobile and persistent CEC, the risks of crop, soil and surface water contamination by most other CECs is even smaller. The fraction of the irrigated CEC mass that seeps into surface water channels from the phreatic aquifer decreases exponentially with the distance between the agricultural plot and the channel, and increases exponentially with the agricultural plot width. Thus, the studied subsurface wastewater irrigation system reduces the environmental impacts of marginal water discharge and agricultural water use, with minimal risk of crop and environmental contamination.

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Transport and degradation of propylene glycol in the vadose zone: model development and sensitivity analysis

Cited by 6 publications

References 34 publications

Environmental and Economic Impact of the Antifreeze Agents in Geothermal Heat Exchangers

Environmental and Economic Impact of the Antifreeze Agents in Geothermal Heat Exchangers

Constraints of propylene glycol degradation at low temperatures and saturated flow conditions

Managed aquifer recharge with marginal water for irrigation and contaminant attenuation

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