Institut National De La Recherche Scientifique

Institut National De La Recherche

Rajeshwar D Tyagi

Jean-Francois Blais

Guy Mercier

Rajwinder Kaur

Fatima Hammy

Jean C Auclair

Jean-Louis Sasseville

Devender K Jain

Nathalie Meunier

Denis Couillard

A process for producing polyhydroxyalkanoates (PHA) is provided. The process comprises: providing a waste stream comprising lignocellulosic materials; adding an calcium-containing mineral to the waste stream; heat-treating the waste stream in the presence of the calcium-containing mineral, to obtain a treated waste stream; fermenting at least one strain of PHA-producing microorganism in a culture medium comprising the treated waste stream as a carbon source, to produce the PHA; and extracting the PHA from the PHA-producing microorganism.

Production of polyhydroxyalcanoates from pulp and paper waste streams

The invention relates to a hybrid biological and chemical method for decontaminating sludge containing heavy metals and pathogenic microorganisms, consisting of the following steps: the sludge is mixed with an acidic leaching solution in order to acidify the sludge with a pH which is low enough to solubilize the majority of the heavy metals and to destroy most of the pathogenic microorganisms but which is also high enough to minimize the solubilization of fertilizing elements; oxidation-reduction of more than +400 mv is maintained, liquid-solid separation occurs in order to obtain a solid fraction comprising decontaminated acidic sludge and a liquid fraction comprising heavy metals which are dissolved in a leaching solution; the sludge is neutralized: and neturalized decontaminated sludge is recovered, whereby the fertilizing elements contained therein, i.e. carbon, nitrogen and phosphorus, remain substantially unchanged in relation to the initially contaminated sludge.

Hybrid chemical and biological process for decontaminating sludge from municipal sewage

The present invention relates to a semi-continuous process for removing heavy metals, substantially reducing volatile suspended solids and substantially destroying indicator bacteria from municipal sludges, which comprises: a) adding 1 to 3 g of sulphur per liter to a volume of municipal sludge and allowing the sulphur oxidizing thiobacilli initially present in said sludge to proliferate under aerobic conditions in said sludge being agitated until the pH of said sludge is lowered to about 1.5 to 2.5 which causes heavy metals present in said sludge to be substantially solubilized, the concentration of volatile suspended solids is substantially reduced and the concentration of indicator bacteria to be lowered to a non-toxic level; b) removing about 90% of said low pH sludge and recovering the solubilized heavy metals therefrom; c) adding about 90% of municipal sludge to the remaining low pH sludge of step b), thereby resulting in a sludge mixture having a pH of about 7 to 8; and d) repeating steps a) to c); whereby the thiobacilli are adapted when the time required for lowering the pH of the sludge to 1.5 to 2.5 is about the same in two successive operations.

Semi-continuous bacterial leaching process

The present invention relates to a process for removing heavy metals and substantially destroying indicator bacteria present in municipal sludges, which comprises: lowering, under aerobic conditions, the pH of a municipal sludge from about 7 to 8 to about 2.0 to 2.5 by adding to said sludge 10% by volume of an inoculum containing a mixture of microorganisms comprising Thiobacillus thiooxidans ATCC 55127 and Thiobacillus thioparus ATCC 55128 with 1 to 3 g per liter of sulphur, and incubating for a period of at least 40 hours where the heavy metals originally present in said sludge have been substantially solubilized and the concentration of the indicator bacteria have been lowered to a non-toxic level; and recovering the metals from the low pH treated sludge of step a).

Bacterial leaching process and composition

Growing community of inventors

Ste-Foy, Canada

Rajeshwar D Tyagi