Solid-phase treatment

Lamar RT, JW Evans, J Glaser (1993) Solid-phase treatment of a pentachlorophenol-contaminated soil using lignin-degrading fungi. Environ Sci Technol 27 2566-2571. 

Land farming. This is a solid-phase treatment system for contaminated soils it may be carried out in situ or ex situ. 

Fig. 1 Growth and activity of T. versicolor during a solid-phase treatment of sewage sludge, (a) Ergosterol content (circle) and laccase activity (square) (b) degrading ability measured as ND24 (adapted from [129])...

Table 1 Occurrence and removal of emerging pollutants in thermally dehydrated sewage sludge after solid-phase treatment with T. versicolor... 

Degradation percentages of several UV filters and some of their metabolites in a solid-phase treatment of sewage sludge by T. versicolor are shown in [80]. As treatments were performed in sterile conditions, the near 100% removal efficiencies of those compounds can be attributed to fungal biotransformation. However, experiments in synthetic liquid media with the fungus in the form of pellets are preferable for the in-depth study of each contaminant. 

The results about the removal of UV Filters were contrary to the expected. Higher removals were expected in slurry system for the least hydrophobic UV Filters and lower in solid-phase. 4DHB and BP3, least hydrophobic than OC and EHMC, were completely removed in solid phase and only BP3 was poorly removed in slurry treatment while 4DHB showed recalcitrance. In general, for all UV Filters detected in raw sludge, better removal values in solid phase treatment were obtained. 

Flexibihty in implementation (in situ or ex situ, slurry phase or solid phase, treatment can be scaled to meet site needs). 

The developer claims that one advantage of composting is that it is more effective than other solid-phase treatment systems for soils and slndges contaminated with viscons snbstances snch as coal tar, creosote, or petroleum production facility slndges and still bottoms. 

In the latter case, interphase transfer between solid and gas phases in soil appeared to be potentially significant only for two-ring PAH compounds in test systems that represented solid phase treatment of PAH-contaminated soils. Essentially no loss of HMW PAHs occurred. Any mixing or tilling of the soils will therefore likely enhance some volatilization, but by no means affect all of the PAHs. 

Relying on the activity of the indigenous microfiora, Tremaine et al. (1994) comparatively evaluated three solid-phase treatment strategies according to their ability to remove PAHs from creosote-contaminated soil. These efforts culminated in an initial biodegradation rate 06) of 122 mg total PAH per kg of soil per day with a starting soil total PAH concentration of 500-14 000 mg/kg. However, when biodegradation data are considered over the entire 12-week incubation period, PAH removal appears to be less extensive removal of the HMW PAHs was not described. 

Empirical approaches are useful when macroscale HRR measurements are available but little or no information is available regarding the thermophysical properties, kinetic parameters, and heats of reaction that would be necessary to apply a more comprehensive pyrolysis model. Although these modeling approaches are crude in comparison with some of the more refined solid-phase treatments, one advantage is that all required input parameters can be obtained from widely used bench-scale fire tests using well-established data reduction techniques. As greater levels of complexity are added, establishing the required input parameters (or material properties ) for different materials becomes an onerous task. 

Another solid-phase treatment involves the same approach to enhancing microbial activity but relies on a different way of providing O2. Here, additional air is provided by vacuum extraction of soil above the water table (i.e., the vadose zone or the unsaturated soil layer), thereby supplying the terminal electron acceptor needed by the aerobic bacteria. This process, designed for hydrocarbon-contaminated sites, is termed bioventing or simply venting. 

White rot fungus treatment is similar to other forms of solid phase treatment, with the addition of a fungal inoculant. Bulk agents such as wood chip or com cobs and nutrients specific for growth of fungal populations may be added to optimize treatment conditions. 

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