Peristaltic pump optimises novel bioaugmentation system

Launched at the UK’s recent Environmental Technology (ET) show, the Baccelerator is a novel continuous bioaugmentation system.

Its designed for use in undersized and poorly performing waste treatment plants as might be found in lifescience plants and food processing plants, as well as for applications in land bio-remediation, composting and processing of landfill leachates.

Compact and portable, the Baccelerator is available as a trailer-mounted unit for short-term rental or as a demountable version for longer-term rental or purchase for permanent installation.

Whereas previous bioaugmentation systems from Cleveland Biotech and other suppliers have used batch growth of bacteria, the Baccelerator operates continuously, running unattended for one month at a time, whereupon the supplies of nutrient and liquid or powdered bacteria have to be replenished.

Importantly, the Baccelerator maintains the exponential bacteria growth rate, thereby maximising the effectiveness of the system.

Furthermore, the bacteria in it are grown on the effluent to be treated, rather than an artificial substrate, so they are pre-acclimatised to the effluent. This eliminates the lag associated with using bacteria grown on synthetic media. As a result, Cleveland Biotech believes that the Baccelerator’s continuous bioaugmentation process is unique for this type of application (Fig.1).

Continuous culture

In a continuous culture, a bacterial species with a doubling time of two hours, if fed with a complete volume change of fresh effluent – nutrients – every two hours, will produce 12 times the amount of maximally growing bacteria compared with a similar batch growth system over the same period of time.

In order to deliver the maximum efficiency, the bacteria used are specifically selected to match the requirements of the treatment site. The resulting continuous feed of bacteria boosts the resident microbial activity of the effluent treatment plant and/or overcomes any transient biological shocks that may have impeded the natural microbial degradation processes within the plant.

Clearly the rate at which the effluent is pumped through the activation unit is crucial to the successful operation of the process: run the process too slowly and the efficiency will be compromised; run it too fast and the bacteria will not have time to achieve exponential growth.

Previously Cleveland Biotech had used a submersible pump with an orifice plate to control the flow rate.

However, effluents often contain solids or particles that can easily block an orifice plate, causing the whole process to stop working. By redesigning the system around a Watson-Marlow Bredel 700 series peristaltic process pump, the company has completely eliminated the problem of blockages because the pump is inherently tolerant of the presence of soft solids and small particles.

A standard off-the-shelf baseplate pump model 701FB/R has been selected. The inverter drive mounted on the Baccelerator's control panel enables accurate control of the motor speed and hence flow rate, which in turn optimises the bacterial growth rate to suit site-specific requirements.

Cleveland Biotech has designed the Baccelerator for a monthly maintenance regime, mainly for the replenishment of the bacteria and the nutrient reservoir. Every second month, the Marprene tubing has to be repositioned so that a fresh length is located in the pumphead. This is a simple, quick operation.

Tony Brooke, development director at Cleveland Biotech, comments: “Having previously used Watson-Marlow Bredel peristaltic pumps for university research projects and in commercial systems, I had full confidence in the company and its products.

“As soon as we realised the submersible pumps and orifice plates were not up to the job, we switched to Watson-Marlow Bredel peristaltic pumps. This has made the world of difference, as it gives us a level of controllability that we did not have before, enabling the process to be optimised so that customers benefit from extremely cost-effective bioaugmentation.

“Indeed, the controllable pump proved to be so successful that we designed the rest of the equipment around that one component.”

He continues: “Wherever possible we have designed the Baccelerator around standard components in order to minimise costs, and Watson-Marlow Bredel was able to recommend a baseplate pump that was perfect for our requirements. Furthermore, with the motor and pumphead supplied pre-mounted together on the baseplate, it is simple for us to integrate the pump within the Baccelerator.”

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