Chemical Bioreactor: A Feasible Solution to Water Purification

Kurt Blohm

Summary:

The chemical bioreactor is a sand filter that can convert water contaminated with raw sewerage into high purity, potable water without the use of electricity, expensive chemicals or other energy intensive processes typically associated with water purification. The current model, the Mark I, utilizes demand-operated slow sand filtration through self-remediation, and its operation is similar to that of a Manz Filter 1-4 . It is a PVC column, 12 inches in diameter containing three sand layers of increasing coarseness with respect to column depth, and one gravel layer near the output port at the bottom of the reactor. The goal of this project is to improve the quality of the water produced by the Mark I through the complimentary application of chemical biocides without hindering its cost, convenience, ease of operation and overall effectiveness.

The Mark I has had much success abroad as a feasible water solution for many disadvantaged communities in Africa and South America . However, research has shown that the water produced by the Mark I and other similar sand filters is only 90 +/- 5% free of harmful pathogens. My advisor Bob McDonald, his colleagues at Aqua Clara and other interested parties agree that this figure can be improved to 99.99% by adding an inter-halogen compound and a copper based material to augment the bioremediation within the reactor. The copper based material will be added to the depth of the sand bed and is used because it does not disrupt the biological mechanisms that enable self-remediation. The inter-halogen compound will be diffused into a separate cavity at a controlled rate by the use of an ion exchange resin which contains this biocide and permits its safe handling and use.

Currently, the Mark I is being tested for total fecal coliform bacteria at Zeeland Fresh Water in Zeeland, MI, using raw sewage from their facility. More in depth testing of specific pathogens is being conducted at E-lab in and Environmental Resource Management, both of Holland , MI . Thus far, results have confirmed the findings of previous research regarding the flow rate, coliform count, turbidity and appearance of the water effluent from the Mark I. Concurrently, the Mark II is being constructed to test the effects of both biocides' addition to the reactor. The copper based compound is being added in solution form to the reactor influent. A separate PVC column will be employed for the dosages of the halogen compound. This companion reactor contains a mechanism that can alter the height of the ion exchange resin, which will adjust the residence time, and consequentially the amount of the inter-halogen compound in the water of the second cavity. The Mark II has the capabilities of changing various parameters so that in depth analysis can be performed and conclusions can be drawn about the efficacy of the application of these biocides on the water from the bioreactor.

 

The ultimate goal of testing with the Mark II is the design of the Mark III, which would contain both the sand bed with a copper-based biocide, and the second cavity in one robust package. Several concepts for the Mark III are proposed in this report, but until further testing is done on the Mark II, the design specifications for the Mark III will remain uncertain.