In an application of the process, the sterilisation system feeds an aliquot of paper sludge into the chamber of a decontamination vessel. Heat is provided to feedstock through direct contact between the reactor wall and direct steam injection. Sterilisation commences once the content of the decontamination unit reaches the desired temperature where it is maintained for about an hour. The unit is depressurised after sterilisation maintaining a positive pressure either by keeping an elevated temperature or by pressurising the unit with sterile air. The content of the decontamination unit is well mixed, during heating-up, sterilisation and depressurisation to ensure break-up of particles into a fine mix. The purpose of the mixing at elevate temperature is to evict trapped and sheltered organisms from the matrix of the feedstock. The mixture is loaded into a decontamination chamber. It is essential that the decontamination part of the process remain under elevated temperature to maintain sterility. A steam jacket surrounds the chambers and valves. After the sterilisation process the sterile product is pumped into the biofuel reactor vessel.
The high bioburden of paper sludge makes it very difficult to ferment. Unwanted paper sludge enters the fermenter via the paper sludge and becomes competition for the fermenting organism.
The process/system suggested utilized agitation, saturated steam and a sterile discharge to reduce the bioburden of paper sludge prior to entering the fermenter. Less or no organisms are therefore available to compete with the fermenting organism.
Apply internal mixing to disrupt the three-dimensional structure of the industrial by-product. Microorganisms become more vulnerable when exposed and thus more likely to be killed.
Aseptically transport the treated product from one unit operation to another without being exposed to the environment. Steam pressure and internal screw to assist with transportation.
Patented in South Africa as ZA 2020/06796
South Africa and the rest of the world are trapped inside a fossil fuel economy. Transport, electrical, heating and cooling services make use of fossil fuel. However, fossil fuel is a non-renewable resource and its use contribute to global warming. Carbon neutral sources, such as paper sludge, therefore, presents an alternative to fossil fuel since they may serve as feedstock to biofuel production. Changing over from a fossil to a biofuel economy presents several challenges. Reducing the bioburden of biomass is one of those challenges that need to be resolved in order to produce a sustainable biofuel economy.