Modelling and Control of Steam Soil Disinfestation Processes (original) (raw)
Steam as a Preplant Soil Disinfestant Tool in California Cut-flower Production
Horttechnology, 2013
ADDITIONAL INDEX WORDS. methyl bromide alternatives, weed control, pathogen, lily, sunflower SUMMARY. Methyl bromide (MB) has been widely used in California cut-flower production for effective control of a broad range of soil pests, including plant pathogens and weeds. However, MB is an ozone-depleting substance, and its availability to growers is limited according to the Montreal Protocol guidelines. Steam has been suggested as a nonchemical option for preplant soil disinfestation. Five trials were conducted in protected greenhouse structure or open-field cutflower nurseries in Monterey, San Luis Obispo, and Ventura counties to evaluate the effect of steam application, alone or in combination with solarization, on soilborne plant pathogen populations, weed densities, and crop growth. Several steam application methods were used including steam blanket, spike-hose, buried drip irrigation lines, or drain tile, and these varied among trials. Calla lily (Zantedeschia aethiopica) nursery trials initiated in 2007 and 2008 showed that steam alone or with solarization was similar to or more effective than MB:chloropicrin (MBPic), applied via drip lines, in controlling weeds and Verticillium dahliae at 6-inch depth. Trials conducted in Spring and Fall 2009 in an oriental hybrid lily (Lilium sp.) nursery showed that, 112 days after steam treatment (DAT) in the spring, the steam (spike-hose) treatment had fewer Fusarium oxysporum propagules than the MB treatment. Lily plant growth in the steam-treated plots was similar to MB-treated plots and taller than in control plots. In the fall trial, fewer lily plants emerged by 44 DAT in the untreated control than in steam-and MB-treated plots and steam was not as effective as MB in reducing Pythium populations. In the 2010 sunflower (Helianthus annuus) and bupleurum (Bupleurum griffithii) trial, all steam treatments reduced Pythium and Phytophthora cactorum survival compared with the untreated control plots, whereas weed densities were reduced only in the spike-hose steam-treated plots. These trial studies showed that steam appeared as effective as MB in suppressing pathogens and weeds and improving crop growth in cut-flower nurseries. However, additional information on fuel consumption, treatment time efficiency, and long-term effects of steam treatment on soil health are needed before steam can be recommended as a viable alternative to MB in California cut-flower nurseries.
International Journal of Fruit Science, 2016
Increasingly stricter fumigant regulations will limit their use and require effective non-fumigant treatments if large-scale strawberry production is to continue in California. Steam has long been used for soil disinfestation in greenhouse soils where it controls most soil pests. The challenge of field-scale soil disinfestation with steam in place of fumigants is availability of machinery capable of treating a large acreage in a timely manner while making the most efficient use of fuel and water. Steam can be a component within an integrated set of fumigant and nonfumigant practices. Steam used together with other practices may permit technically and economically sustainable strawberry production into the future by allowing growers to adapt to more stringent fumigant use restrictions. It may be possible to overcome some of the limitations of steam because steam generator technology has advanced in recent years as well as recent developments in co-applications with steam, including exothermic compounds co-applied with steam and mustard seed meal coapplied with steam. Regarding steam generator technology, direct-fire steam generators are more energy efficient than traditional steam boilers and avoid the hazards of steam pressure vessels. Steam is arguably the most effective non-fumigant method of soil disinfestation and it likely has a role in a future California strawberry production system that is forced to use much less fumigant than it does at present.
Journal of Contaminant Hydrology, 2000
The efficiency and effectiveness of soil vapor extraction SVE and bioventing BV systems for remediation of unsaturated zone soils is controlled by a complex combination of physical, Ž. chemical and biological factors. The Michigan soil vapor extraction remediation MISER model, a two-dimensional numerical simulator, is developed to advance our ability to investigate the performance of field scale SVE and BV systems by integrating processes of multiphase flow, multicomponent compositional transport with nonequilibrium interphase mass transfer, and aerobic biodegradation. Subsequent to the model presentation, example simulations of single well SVE and BV systems are used to illustrate the interplay between physical, chemical and biological processes and their potential influence on remediation efficiency and the pathways of contaminant removal. Simulations of SVE reveal that removal efficiency is controlled primarily by the ability to engineer gas flow through regions of organic liquid contaminated soil and by interphase mass transfer limitations. Biodegradation is found to play a minor role in mass removal for the examined SVE scenarios. Simulations of BV systems suggest that the effective supply of oxygen may not be the sole criterion for efficient BV performance. The efficiency and contaminant removal pathways in these systems can be significantly influenced by interdependent dynamics involving biological growth factors, interphase mass transfer rates, and air injection rates. Simulation results emphasize the need for the continued refinement and validation of predictive interphase mass transfer models applicable under a variety of conditions and for the continued
Biology and Fertility of Soils, 2010
Steam soil disinfestation is efficiently used in the field for pre-planting pest control. Providing steam to the soil must have consequences, either beneficial or detrimental for the soil functioning. We set up a laboratory experiment to quantify the soil quality dynamics induced by this agricultural practice. In steamed and control soil, we monitored the size, the activity, and the genetic structure of the bacterial community in the top 2 cm soil every second day over a 10-day period after the treatment. We also characterized the bioavailable organic matter using fluorescence and ATR-FTIR spectroscopy. We showed that steaming induced the release of twice as much dissolved organic carbon in steamed soil as in the control soil. This extra carbon was much less fluorescent and contained a higher proportion of aliphatic compounds (alkyl chains, primary alcohols). After an initial drop in the bacterial community, we observed a tenfold increase in the number of bacteria, a flush in carbon mineralization, and genetic structure modification, which could be related to the newly released carbon. Steam treatment showed strong but quickly reversible impacts on the soil functioning, enabling farmers to sow approximately 1 week after treatment.
Performance Comparison of Control Strategies for Plant-Wide Produced Water Treatment
Energies, 2022
Offshore produced water treatment (PWT) accounts for cleaning the largest waste stream in the offshore oil and gas industry. If this separation process is not properly executed, large amounts of oil are often directly discharged into the ocean. This work extends two grey-box models of a three-phase gravity separator and a deoiling hydrocyclone, and combines them into a single plant-wide model for testing PWT control solutions in a typical process configuration. In simulations, three known control solutions—proportional-integral-derivative (PID) control, H∞ control, and model predictive control (MPC)—are compared on the combined model to evaluate the separation performance. The results of the simulations clearly show what performance metrics each controller excels at, such as valve wear, oil discharge, oil-in-water (OiW) concentration variance, and constraint violations. The work incentivizes future control to be based on operational policy, such as defining boundary constraints and ...
HortScience
Soil disinfestation with steam has been evaluated in strawberry fruiting fields as a nonchemical method of soil disinfestation; however, little is known about the use of steam for field production of strawberry daughter plants. The objective of this study was to compare daughter plant production in soils previously treated with steam compared to those treated with standard methyl bromide (MB) and chloropicrin (Pic) treatments. A prototype field steam applicator and a self-propelled diesel-fueled steam generator and applicator were tested at two high-elevation nurseries near Macdoel, CA, in Sept. 2018 and Aug. 2020, respectively. The steam application heated the soil above 60 °C for ≈60 minutes to a depth of 25 cm at both nurseries. The pest control efficacy of the steam applications against weeds, Verticillium spp., Tylenchulus semipenetrans, and Pythium ultimum were similar to that of MB:Pic. The stolons and daughter plants densities in fields with steam treatment were similar to t...
The Influence of Steam on Some Chemical Soil Properties - Review
Agricultura, 2020
Soil forms a thing mantle over the Eart¢s surface and acts as the interface between the atmosphere and lithosphere, the outermost shell of the Earth. It is a multiphase system, consisting of mineral material, plant roots, water and gases, and organic matter at various stages of decay (Bardgett R., 2005,). Soil temperature influence plant nutrients uptake through a multitude of chemical, physical and biological processes that intercat over wide range of spatial and temporal scales (BassiriRad H, 2005) Steaming is traditionally used in glasshouses to sterilise the soil and control both weeds and diseases prior to crop establishment. Steam is applied under pressure beneath metal pans forced down onto freshly formed beds for periods of 3-8 minutes. The steam raises the soil temperature to 70-100 °C killing most weed seeds to a depth of at least 10 cm. The increase in inorganic substances in soil due to steaming means an increased fertility as more nutrients become available for the plan...
Microbial Activity of Soil Following Steam Treatment
The effect of steam treatment on subsurface aerobic and anaerobic microbial communities was investigated using multiple microbial assays. Soil samples were gathered and analyzed prior to, one month after, and eight months after a five-month field pilot test of steam injection and extraction. Aerobic soil samples were analyzed by respirometry, plate counts, and direct microscopic counts. Anaerobic microbial activity was examined by monitoring methane generation in anaerobic microcosms with gas chromatography. Respirometry showed pre-steam CO2 production was consistent with natural attenuation, post-steam (one month) CO2 production was below detection, and post-steam (eight months) CO2 production was about half of pre-steam. Post-steam (one and eight month) plate counts were one to four orders of magnitude lower than the pre-steam samples. Direct microscopic counts showed post-steam (one and eight month) cell numbers were higher than the pre-steam counts, but based on plate counts the...
Kinetic modelling of a diesel-polluted clayey soil bioremediation process
The Science of the total environment, 2016
A mathematical model is proposed to describe a diesel-polluted clayey soil bioremediation process. The reaction system under study was considered a completely mixed closed batch reactor, which initially contacted a soil matrix polluted with diesel hydrocarbons, an aqueous liquid-specific culture medium and a microbial inoculation. The model coupled the mass transfer phenomena and the distribution of hydrocarbons among four phases (solid, S; water, A; non-aqueous liquid, NAPL; and air, V) with Monod kinetics. In the first step, the model simulating abiotic conditions was used to estimate only the mass transfer coefficients. In the second step, the model including both mass transfer and biodegradation phenomena was used to estimate the biological kinetic and stoichiometric parameters. In both situations, the model predictions were validated with experimental data that corresponded to previous research by the same authors. A correct fit between the model predictions and the experimenta...
Removal of volatile and semivolatile organic contamination from soil by air and steam flushing
Journal of Contaminant Hydrology, 2001
A soil core, obtained from a contaminated field site, contaminated with a mixture of volatile Ž . and semivolatile organic compounds VOC and SVOC was subjected to air and steam flushing. Removal rates of volatile and semivolatile organic compounds were monitored during flushing. Air flushing removed a significant portion of the VOC present in the soil, but a significant decline in removal rate occurred due to decreasing VOC concentrations in the soil gas phase. Application of steam flushing after air flushing produced a significant increase in contaminant removal rate for the first 4 to 5 pore volumes of steam condensate. Subsequently, contaminant concentrations decreased slowly with additional pore volumes of steam flushing. The passage of a steam volume corresponding to 11 pore volumes of steam condensate reduced the total VOC concentration in the Ž . soil gas at 208C by a factor of 20 to 0.07 mgrl. The corresponding total SVOC concentration in the condensate declined from 11 to 3 mgrl. Declines in contaminant removal rates during both air and steam flushing indicated rate-limited removal consistent with the persistence of a residual organic phase, rate-limited desorption, or channeling. Pressure gradients were much higher for steam flushing than for air flushing. The magnitude of the pressure gradients encountered during steam flushing for this soil indicates that, in addition to rate-limited contaminant removal, the soil Ž y9 2 . permeability 2.1 = 10 cm would be a limiting factor in the effectiveness of steam flushing. q