BIOBRUSH – scientific research on bioremediation and its potential for conservation practice on stone monuments

The occurrence of salt crusts and incrustations on stonework in monuments, caused by nitrate and sulphate pollution, induces accelerated weakening and deterioration of the matrix. Until now, the remediation of stone pathologies such as black crusts, containing sulphate and uncombusted hydrocarbons, has been carried out using chemical or physical methods, often associated with detrimental effects. Even when water is used, as for nitrate removal, it can permeate the stone and cause negative effects. There is considerable evidence that microorganisms can remove salts that accumulate in crusts of damaged stone [1, 2] while others have been shown to deposit minerals that consolidate stone materials [3, 4]. The EC-funded project BIOBRUSH aimed to produce an innovative treatment based on bioremediation, combining crust destruction (by mineralising bacteria) with mineral production (via biocalcification). The BIOBRUSH research objectives were: 1. To assess stone crusts from historic buildings and monuments across Europe 2. To establish a European bacterial culture collection for use in stone bioremediation 3. To investigate the efficacy and optimise the stone bioremediation process 4. To carry out risk assessments on stone minerals and bulk properties in laboratory studies 5. To perform in situ field trials on buildings or monuments