RE: HEAT TO KILL MOLD AND PCP'S

[Guest guest]

This looks more like an advertisement to promote an existing technology for

something other than its original intended use than like a scientific paper.

PCP has a boiling point over 300 degrees C, far higher than the 60 degrees C

used. This is high enough to vaporize some PCP near the wood surface, but

not high enough to remove all from inside the wood. PCP is soaked into wood

in solution in some solvent, possibly water, possibly alcohol. It exists in

the dried woodd as a solid-in-solid suspension. This is not easily

mobilized, and the temperature used, even with added humidity is probably

insufficient to do much more than as described in the article- raise the

airborne level of PCP a little. Removing contaminated wood would be more

efficient at solving this type contamination.

Date: Tue, 08 Nov 2005 00:04:44 -0000

From: " carondeen " <kdeanstudios@...>

Subject: HEAT TO KILL MOLD AND PCP'S

http://palimpsest.stanford.edu/byauth/gagelmann/gagelmann.html

First results of a pilot decontamination in a PCP polluted building

by means of a humidity controlled thermal process

Abridged translation. The original paper was written in German and

contains additional information.

W. von Rotberg1, M. Gagelmann2, H. Piening3, R.W. Sieke4, S.

is5, N. Wilke1 and K.Roux6

1Thermo Lignum GmbH, Landhausstrasse 17, 69115 Heidelberg, Germany;

2Öko-Consult Dr.rer.nat.habil. M Gagelmann GmbH, Wormserstrasse 9,

69198 Schriesheim, Germany;

3Bayrische Verwaltung der Schlösser und Gärten, Residenzstrasse 1,

80333 München, Germany;

4Technologie Consulting GmbH, Echterngrund 19, 30657 Hanover;

5Thermo Lignum Buehner & Co. GmbH, -Lincke-Ufer 42-43, 10999

Berlin;

6Thermo Lignum UK Limited, 19 Grand Union Centre, London W10 5AS, UK

Introduction

Up till the early Eighties preventative treatments of construction

and ancillary materials even in interiors and of wooden and textile

objects as well as those made of, e.g., paper and leather as a

precaution against insect and fungal attack used to be carried out

using pentachlorphenol (PCP) as active ingredient. PCP evaporation

from such large material surfaces treated in such a manner can reach

levels of concentration even today which are still hazardous to

human health (Gagelmann and Fonfara, 1992).

It is possible to record even today very high levels of interior

contamination from pentachlorphenol (PCP) particularly in buildings

of historical significance with many wooden interior fittings. There

are as yet no appropriate methods to decontaminate protected

historic buildings or objects. All processes in use hitherto, such

as the steam-tight panelling, the removal or encasement and surface

coating of contaminated construction elements cannot be justified

from a curatorial point of view. It was therefore the aim of the

investigation to test the application of a new humidity-controlled

thermal process with which it is possible to evaporate out the

volatile wood preserver ingredients contained in the surfaces to be

treated so as to arrive at a distinct improvement of interior air

quality.

The humidity-controlled thermal treatment processed developed and

patented by Thermo Lignum has been successfully used for several

years for the purpose of disinfestation from insect pests in items

made of organic materials, notably works of art, museum exhibits,

antiques, libraries and archives. Another application is the

treatment of mould on objects and dry rot in buildings.

In an earlier pilot project it was possible to demonstrate the

beneficial effect of the Thermo Lignum method when an small

reconstructed cottage was treated against wood-boring infestation in

its structural timbers. The building was heated to a core

temperature of 55 °C in the same way as described above. This

particular infestation treatment was completed in under 24 hours due

to its size and the fact that a holding phase of one to two hours is

sufficient to achieve a 100% kill rate of all forms of infestation.

This was the first time this pioneering treatment involving combined

heating and humidity control had been carried out on a whole

building (Zeuner, 1997).

Materials and Methods

After preliminary tests on a laboratory scale the applicability in

principle of a humidity-controlled thermal process for the

detoxification of contaminated interiors could be confirmed. The

process consists of the heating of a closed room whilst

simultaneously controlling its humidification. The room to be

treated is sealed off tightly and is slowly heated to 60°C by

inducing hot air from a closed-circuit heating system developed and

patented by Thermo Lignum GmbH,Germany, which ensures an even air

distribution throughout the room. (The maximum heating capacity/hour

of the modular system is 8,000 m3 thus making large-scale

decontamination possible). Structural damage due to drying out is

pre-empted by keeping the relative humidity (50%) in the induction

air constant by means of a computer-assisted control unit. Room

temperature increases gradually guided by the wood and masonry core

temperatures (Nicholson and von Rotberg, 1996). After reaching the

target temperature there follows a holding phase lasting several

days up to several weeks during which time the contaminants are

mobilised.

At the same time the mobilised contaminants are broken down by means

of oxidation in the sealed reaction compartment of a separate

parallel air cycle. The reactive oxidation product is generated for

this purpose in an ozone generator in which oxygen molecules are

converted into radicals which form ozone structures in high levels

of concentration with half lives between 70 msec and 70 sec.

To verify the success of the decontamination treatment air

measurements were taken after a 14 to 16 hour long closing of the

room and at temperature levels typical for residential occupation.

Air sampling (2-3 m3; 2 m3/hour) was done on fibre glass filters

(dust phase) and polyurethane foams (gaseous phase) (Leitfaden 1994;

VDI 4300, 1994). Following specific extraction with toluene analysis

gas chromatography mass spectrometry was carried out.

Results and Discussion

In the first phase of the pilot decontamination a severely PCP

contaminated room of an approximate volume of 72.5 m3 (room I) with

a room contamination load ratio of approx. 1.2 m-1 (contaminated

wood surface/ room volume) was subjected to a ten day long

decontamination treatment. The emission into the ambient air

emanated from structural timbers (half-timbering) and decorative

wood (ceiling beams, wall panelling, etc.) with surface

contamination readings ranging from 360 to 4000 mg PCP/kg. Depending

on the point of measurement (window areas with lesser and rear wall

area with higher timber content) the PCP concentration in the

ambient air ranged from 1112 to 1186 ng/m3 (22.7 °C) with 792-759

ng/m3 apportioned to the dust phases. Similarly, for ne the

ambient air measurements ranged from 220-223 ng/m3 (gaseous and dust

phases).

Measurements after the decontamination treatment (23.8 °C) resulted

in significantly lower PCP contamination of the ambient air of 182-

367 ng/m3 (71-143 ng PCP/m3 in the dust phase). A similar reduction

of the ne contamination of the ambient air could also be

recorded (143-150 ng/m3).

As a consequence of these results the scope of the decontamination

was enlarged to include four other rooms. Room I was included again

in the second phase (approx. 205 m3) of the pilot decontamination

and the holding phase was extended to 14 days. A compilation of the

test results is given in Table 1.

Table 1:

Development of PCP and ne contamination of the ambient air

after the second decontamination phase in two selected test rooms

(Room I) treated in the first decontamination phase and an

additional test room II with an interior room contamination load

ratio of 0.67 -1 with reading points at rear wall, room centre and

window wall. The PCP measurement results of the relevant gaseous

phase are emphasised in bold letters.

Test Room/Reading point Days after Decontamination Temperature °C

Dust phase/Gas phase ne ng/m3 PCP ng/m3

I/Rear wall 2 24.6 Dust phase 372

Gas phase 80 391

I/Window 2 25.6 Dust phase 235

Gas phase 62 444

I/Rear wall 9 19.9 Dust phase 372

Gas phase 46

I/ Centre 9 20.1 Dust phase 501

Gas phase 52 40

I/Mitte 26 20.3 Dust phase 281

Gas phase 19

II/Centre 22 21.4 Dust phase 201

Gas phase 3

The investigation two days after the completion of the second

decontamination phase still showed an increased PCP contamination of

the ambient air in room I. The reasons for this may be sought in the

diffusion rate still being accelerated at this point in time,

possibly due to a building core temperature still above normal

and/or a mobilised secondary contamination from the extended

decontamination scope, and these need to be further discussed.

Contrary to the PCP measurements the ne concentration in the

ambient air followed the expected trend towards increasingly lower

results. However, readings after 9, 22 and 26 days show a rapid

reduction for the gaseous phase to concentration levels below 20

ng/m3 (background level).

The increased dust contamination in the air does not come unexpected

since, as a consequence of the humidity-controlled thermal

decontamination, surface consolidant coatings, such as fats, oils,

soot, etc. are (visibly) removed. A reduction of the dust

contamination of the ambient air can be achieved by conventional

cleaning and consolidation methods for all surfaces.

The decontamination time (holding phase) may be shortened, depending

on the air accessibility, by raising the heating temperature and

relative humidity. The possibility of an oxidative breakdown of

mobilised interior contaminants even outside the reaction

compartment is currently being investigated. The applicability of

the process to other active ingredients of low volatility (e.g.

permethrine) which have been applied as a pest control measure has

also been investigated successfully.

Literature

Gagelmann, M. and Fonfara, J.J.: " Sick building syndrome " und

Innenraumbelastungen durch Holzschutzmittel, polychlorierte

Biphenyle, Asbest und kuenstliche Mineralfasern. ( " Sick building

syndrome " and interior contamination from wood preservatives,

polychlorinated biphenyls, asbestos and synthetic mineral fibres).

Klin. Lab. 38 (1992) 447-455.

Nicholson, M. and von Rotberg, W.: Controlled environment heat

treatment as a safe and efficient method of pest control. In:

Proceedings of the 2nd International conference on Insect Pests in

the Urban environment (K.B. Wiley, publisher), Herriott-Watt

University, Edinburgh, Scotland, 7 to 10 July 1996., 263-265.

Leitfaden für die erste Ermittlung der Belastungssituation für

holzschutzmittelbehandelte staatliche Gebäude, Oberste Baubehörde im

Bayrischen Staatsministerium des Innern (Stand 29.11.94).

(Guidelines for a first assessment of the contamination levels in

government buildings treated with wood preservatives, update 29 Nov.

94. Superior Building Directorate in the Bavarian Interior Ministry).

VDI-Richtlinie 4300: Messen von Innenraumluftverunreinigungen.

Messtrategie für Pentachlorphenol (PCP) und y-hexachlorcyclohexan

(LIndan) in der Innenraumluft. Kommission Reinhaltung der Luft im

VDI und DIN. Arbeitsgruppe PCP/n. VDI- Handbuch Reinhaltung der

Luft, Band 5 (Entwurf: November 1994) (The measurement of interior

air pollution. A measuring strategy for pentachlorphenol (PCP) and y-

hexachlorcyclohexane (ne) in the interior air. Commission for

the preservation of air purity in the VDI and DIN. Working group

PCP/ne. VDI Handbook Preservation of air purity, volume 5

(Draft: Nov. 1994))

Zeuner, D. (Ed.) : Whittaker's Cottages move into the space age.

Weald & Downland Open Air Museum Magazine, Vol. 7/8 No 17., March 1997.

--------------------------------------------------------------------------------