System for biological purification of water containing organic materials and derivative products

Claim 1

A process for biologically purifying aquarium water and aquaculture ponds water as well as fresh water or salt water carrying solid organic substances or dissolved organic substances or dissolved mineral substances from the degradation of said organic substances which process comprises: (a) flowing water to be purified through at least one path; (b) stirring and contacting said water to be purified, in said path, with oxygen or with an oxygen rich gas, to provide aerobic conditions in said water to be purified; (c) filling a confined volume with oxygen impoverished water to provide anaerobic conditions and linking, through a porous connector, said confined oxygen impoverished water with said water to be purified: (i) creating in the thickness of said connector, one aerobic zone in contact with said water to be purified, and one anaerobic zone in contact with said confined water, and (ii) establishing between said water to be purified and said confined oxygen-impoverished water, gradients of concentration of dissolved mineral substances that compel said mineral substances to diffuse throughout said porous connector according to said gradients of concentration; (d) introducing unicellular aerobic microorganisms in said porous connector aerobic zone in contact with said water to be purified, to transform into mineral substances, solid as well as dissolved organic substances carried by said water to be purified; said aerobic microorganisms comprising bacteria that transform organic nitrogen into NH 4 + , then NH 4 + into NO 2 - , then NO 2 - into NO 3 - ; (e) introducing unicellular anaerobic microorganisms in said porous connector anaerobic zone in contact with said confined water, to reduce said mineral substances; said anaerobic microorganisms comprising heterotrophic denitrifying bacteria which transform into molecular nitrogen and oxygen nitrites and nitrates that diffuse from said porous connector aerobic zone to said porous connector anaerobic zone; (f) substantially preventing light from reaching said porous connector anaerobic zone to prevent any photosynthetic oxygen release in said porous connector anaerobic zone; and (g) introducing in the thickness of said porous connector pluricellular burrowing detritus-eating animals that supply said heterotrophic denitrifying bacteria with organic carbon; said organic carbon coming from organic substances carried by said water to be purified and being incorporated into said porous connector anaerobic zone by the excretion as well as by the biostirring activity of said burrowing detritus-eating animals; said biostirring activity being sufficiently low to maintain in said porous connector an oxygen-impoverished zone having an oxygen content not exceeding about 1.5 mg/l and an oxygen-rich zone having an oxygen content greater than said oxygen-impoverished zone.