Petroleum Bioventing

J. van Eyk

• Verlag: Routledge
• Jahr: 2022
• ISBN:
  9781351425209
• Auflage: 1
• Thema: Biowissenschaften
• Thema: Biotechnologie

Petroleum bioventing is a new technique for the biological in situ removal of petroleum hydrocarbons from soil. This book investigates the composition and the behaviour of petroleum in soil, soil properties and soil processes, their interaction with bacterial processes, possibilities for optimizing the removal of petroleum hydrocarbons from soil by bacteria and it explains the phenomenon of recalcitrance. This interdisciplinary approach forms the basis for both modelling and design principles of bioventing.Key features: Background knowledge on the physical/chemical/biogeochemical properties of soil and soil processes with respect to petroleum bioventing; Background knowledge on petroleum biodegradation and noval approaches to stimulate petroleum biodegradation to stimulate petroleum biodegradation in soil and biofilters; Modelling efforts showing the effect of diffusion and soil porosity on bioventing design and the effect of ventilation quotients on the aeration & biological clean up of soils, particularly heterogeneous soils; New insights into biological removal of priority pollutants from petroleum hydrocarbons, the problem of residual concentrations of petroleum hydrocarbons in soil & the requirements by the Law on Soil Protection.

Part 1

Background knowledge

CHAPTER 1

Historical background

It all started in 1979, when people in Lekkerkerk (a village in the Netherlands) were shocked to find, that they (268 house owners in total), were living on top of heavily polluted soil. As a result of the furore which this discovery caused, the Government took it upon themselves to solve the problem in a grand way and worked out a plan:

– To evacuate 871 inhabitants into campers off-site,

– To excavate approximately 100,000 m³ soil,

– To excavate 1600 drums, containing, cadmium, lead benzene, toluene, xylene, and poly chlorinated biphenyls,

– Entailing a procedure to reimburse house owners and tenants alike.

Following this so called Lekkerkerk-incident, the Ministry of Public Health and Environmental Hygiene (as it was called at that time), decided to set up an inventory to include all possible former dump sites of chemical wastes (Ginjaar Inventory). As a result of this investigation, 3000 sites were identified as being suspect, 350 of which eventually turned out to require urgent remediation.

However, in the mid-eighties it became apparent, that the contemporary industrial sites, in addition to derelict industrial sites (particularly gaswork sites), were also polluted (Mischgofsky 1991¹).

Although regulatory issues will be discussed in more detail in Chapter 16: Complying with the Law on Soil Protection in the Netherlands, for the sake of our present discussion it is important to note, that in the wake of the Ginjaar Inventory, two very important laws were introduced in 1987:

1. The Interim Law on Soil Remediation (Interimwet boddmsanering); and

2. The Law on Soil Protection (Wet bodembescherming).

Key element in the Law on Soil Protection is the aim to preserve the multi-functionality of both soil and groundwater and, by the same token, the central theme in (at the time still an ‘Interim’ Law) the Law on Soil Remediation, is the restoration of the multi-functionality of the soil.

The quantitative criterion for heavy metals with respect to multi-functionality was based on natural or background levels (so-called reference, or endpoint values).

However, this criterion is only applicable when it concerns chemicals which, under ‘natural’ circumstances occur in soil or groundwater. For, chemicals which under natural conditions do not occur in soil or groundwater, like chemicals for pest control, the endpoint criterion is below the detection limit which, in view of the ever increasing sensitivity of modem analytical techniques is a moving target.

It will not come as a surprise therefore, after it was decided (on the basis of concentration levels and on an evaluation of possible risks for migration and exposure) that the Lekkerkerk site required urgent remediation, that the only way to comply with this law, certainly in the early eighties, was excavation.

The total remedial costs for the Lekkerkerk site amounted to 180 million Guilders which, other considerations apart, indicated that excavation as a technique to remediate soils can be extremely expensive, particularly when it has to be carried out to great depths or below buildings.

The Lekkerkerk event prompted an investigation into alternative, more cost-effective approaches. A review of the available methods at that time showed that although some techniques, such as soil washing and thermal treatment of soil as a result of active support by the Government, were developing quite rapidly, they still involved excavation prior to treatment onsite or off-site.

The only two alternative in situ approaches which had been considered in the early eighties, as far as could be ascertained, were subsurface venting and the use of surfactants.

Several reports on forced venting, to remove gasoline vapour from a large-scale Model Aquifer, were submitted to the American Petroleum Institute (API) by the Texas Research Institute. The final report was published in 1983 (Texas Research Institute 1984²).

The reported experiments demonstrated, that venting can reduce gasoline vapour concentrations in the soil above a gasoline spill, but no accurate figures for the residual concentrations were reported.

The aim of the use of surfactants is to mobilize immobile oil and to move it into the groundwater table, from where it can subsequently be pumped out and salvaged.

The first experiments carried out on the mobilization of residual oil from soil were reported in 1971 by Somers and Drok (Somers 1971³). The report showed that the effect of a detergent like T-pol on the displacement of oil from soil is negligible.

In that same decade, a series of laboratory experiments on enhanced recovery of spilled gasoline with surfactants had been carried out by the Texas Research Institute (TRI). The final report on laboratory studies carried out to examine the underground movement of gasoline on the water table and the enhanced recovery of gasoline by aqueous solutions of commercial detergents, was published in 1979 (Texas Research Institute 1979⁴). The work was supported by the API and technical support was given by the Task Force on Underground Product Recovery.

These studies showed that a...