Slurries

Monitoring of microbial contamination during production process of slurries and final products

Microorganisms in slurries – a real issue for pulp and paper industry

Paper industry uses a lot of slurries in their process for improving paper printing. Slurries are highly concentrated aqueous suspensions (up to 78%) of calcium carbonates.
Microorganisms’ presence in slurries can be the cause of diverse hazards during paper production and slurries products should be conform to strict quality requirements regarding microbial contamination.
Unfortunately, microorganisms proliferate easily in slurries as they find in this matrix the nutrients and heat required for their growth. Chemical treatments are applied for eliminating bacteria proliferation. However, biocide dosing in slurries is not very precise, linked to the lack of efficient methods for quantification of microorganisms in these samples. Culture based methods for enumerating bacteria are not adapted for slurries. Also, chemical treatments for slurries need to be efficient on all microorganisms, viable cultivable and viable non cultivable microorganisms. Latest scientific publications show that under-optimized chemical treatments do not kill biomass, but create high percentage of viable non cultivable microorganisms, undetected with culture methods but still leading to paper production damages.

QG21I™ – the only tool for microbial quantification in slurries

QG21I kit allows precise and fast quantification of all living microorganisms present in slurries. Developed specifically for industrial process samples, the kit can be used in a laboratory or on field. QG21I kits allow a precise mapping of microbial contamination on the production site, storage, final products, as well as evaluation and validation of chemical treatments implemented in the process.
QG21I kit allows performing two measurements in the same time - living biomass and dead biomass. This double quantification provides an efficient follow-up of total microbial proliferation, including cultivable and non-cultivable microorganisms.  Biocide efficiency tests can be implemented easily in jar-tests for  the determination of  the right dosing of biocide.  A maximum ATP threshold can be determined for guaranteeing the absence of colonies (CFU) using culture tests.

Graph 1: Example for the evaluation of different biocides in white water in slurries production. When ATP is below 100pg/ml, no bacteria are enumerated using culture methods. The 100pg/ml threshold is chosen for this installation for monitoring microbial contamination and implementing corrective actions if required.
Surveillance of microbial quality of slurries is a part of the global process for improving industrial processes, reducing operational costs with respect of environmental issues.

Microbial surveillance using QG21I is the best method for: 

1. Securing microbial quality of products
2. Early detection of degradation of slurries or industrial process and anticipation of microbial drifts
3. Localizing critical points for development of biomass – production or storage
4. Localizing origins of microbial contamination
5. Evaluating and optimizing efficiency of treatments
6. Reducing treatment costs
7. Reducing water use
8. Reducing environmental footprint