Biosensor for water toxicity monitoring
There is provided a biosensor for detecting water contaminants. The biosensor has a microbial fuel cell compartment, having (i) at least one opening to allow water into and out of the microbial fuel cell compartment, (ii) an anode comprising electroactive microorganisms, and (iii) a cathode. The anode is electrically and physically separated from the cathode. The anode is anaerobic and comprises electroactive microorganisms. The cathode is aerobic. The biosensor has a storage compartment housing a biodegradable carbon source to supply the biodegradable carbon source to the electroactive microorganisms; an electric impedance load; an electric switch forming an intermittent connection between the microbial fuel cell compartment and the electric impedance load; an electric sensor; and a control system coupled to the electric switch and the electric sensor, receiving a measurement from the electric sensor, and outputting an indication signaling the presence or absence of the water contaminants based on the measurement.
1 . A biosensor for detecting water contaminants comprising
a microbial fuel cell compartment, the microbial fuel cell compartment comprising (i) at least one opening to allow water into and out of the microbial fuel cell compartment, (ii) an anode comprising electroactive microorganisms, and (iii) a cathode, wherein:
the anode is electrically and physically separated from the cathode,
the anode is anaerobic or micro-aerobic and comprises electroactive microorganisms, and
the cathode is aerobic;
a storage compartment comprising a biodegradable carbon source, the storage compartment being in communication with the anode to supply the biodegradable carbon source to the electroactive microorganisms at a controlled rate to maintain the chemical oxygen demand (COD) at the anode between about 10 mg/L to about 50 mg/L;
an electric impedance load electrically connected to the anode and the cathode thereby forming an electric circuit with the microbial fuel cell compartment;
an electric switch within the electric circuit forming an intermittent electrical connection between the microbial fuel cell compartment and the electric impedance load;
an electric sensor within the electric circuit to measure an electric parameter of the electric circuit; and
a control system coupled to the electric switch and the electric sensor, the control system configured to receive a measurement from the electric sensor, and outputting an indication signaling the presence or absence of the water contaminants based on the measurement,
wherein the control system is configured to intermittently activate the electric switch for a period of time, a measuring period, to allow measurement of the electric parameter, such that during operation of the biosensor the electric switch is off between measuring periods.
2 . The biosensor according to claim 1 , wherein a water delivery control is used to provide a controlled water amount to the microbial fuel cell compartment being from 2 to 5% per water delivery event of a total volume of the microbial fuel cell compartment volume.
3 . The biosensor according to claim 1 , wherein the biodegradable carbon source is supplied to the anode at a flow rate that is substantially constant.
4 . The biosensor according to claim 1 , wherein the biodegradable carbon source is provided in a concentration of between 10 mg/L to 100 mg/L in the anode.
5 . The biosensor according to claim 1 , further comprising a pumping system to supply the biodegradable carbon source from the storage compartment to the anode.
6 . The biosensor according to claim 5 , wherein the pumping system is a capillary pump system or a timer-controlled programmable pump.
7 . The biosensor according to claim 1 , wherein the biodegradable carbon source is a highly concentrated organic material, a solid mass or a gel mass that decays over time by hydrolysis.
8 . The biosensor according to claim 1 , wherein the water contaminants comprise inorganic toxicants or organic contaminants.
9 . The biosensor according to claim 8 , wherein the inorganic toxicants include at least one of Pb, Hg, Cu, Zn, Cd, Cr, Ag, Ni, Fe, Cl, ammonium or a pesticide.
10 . The biosensor according to claim 8 , wherein the organic contaminants include at least one of a hydrocarbon, a biodegradable organic compound, a hydrocarbon derivative, a bacterial toxin, a phenol compound, a formaldehyde, a diazinon, a sulfamethoxazole, a sulfadiazine, a chloramine, or a polychlorinated biphenyl.
11 . The biosensor according to claim 1 , wherein a separator membrane that is ion permeable separates the cathode and the anode.
12 . The biosensor according to claim 11 , wherein the separator membrane is selected from the group consisting of a piece of cloth, a piece of fabric, a proton exchange membrane, an ion exchange membrane, a porous and non-conductive material, and a non-conductive mesh.
13 . The biosensor according to claim 1 , wherein the interval between the measuring periods is at least 5 minutes.
14 . The biosensor according to claim 13 , wherein each of the measuring periods has a duration of equal to or less than 2 minutes.
15 . The biosensor according to claim 1 , wherein the anode comprises an electrically conductive material with a large surface area.
16 . The biosensor according to claim 15 , wherein the conductive material comprises a material selected from the group consisting of carbon felt, carbon paper and granular carbon.
17 . The biosensor according to claim 1 , wherein the cathode is exposed to an oxygen-rich environment.
18 . The biosensor according to claim 1 further comprising a floater component.
19 . A method of monitoring contamination of a body of water with the biosensor according to claim 1 , the method comprising:
obtaining an indication from the biosensor; and
determining the presence of a contaminant based on the indication.