Modular energy recovering water treatment devices

Abstract

A modular device that is optimized for preliminary water treatment and energy generation and methods for operating the same are described.

1 - 19 . (canceled) 
     
     
         20 . A method of optimizing a microbial population on an anode of a microbial fuel cell (MFC) for wastewater treatment, comprising the steps of:
 (a) contacting the anode with a parental microbial population and wastewater;   (b) operating the MFC at a relatively high resistance for a sufficient period of time to increase the biomass of the microbial population on the anode   (c) operating the MFC at a medium resistance for a sufficient period of time to optimize the metabolism of the microbial population of the anode; and   (d) operating the MFC at a low resistance for a sufficient period of time to optimize microbial degradation of the wastewater.   
     
     
         21 . (canceled) 
     
     
         22 . The method of  claim 20 , wherein the high resistance is in the range of about 1000 to 5000 ohms. 
     
     
         23 . The method of  claim 20 , wherein the medium resistance is in the range of about 100-500 ohms. 
     
     
         24 . The method of  claim 20 , wherein the low resistance is in the range of about 10-500 ohms. 
     
     
         25 . A method of treating wastewater, the method comprising:
 (a) providing wastewater to a microbial fuel cell, said microbial fuel cell comprising:
 (i) an anode, wherein the anode is physically associated with a first microbial population; 
 (ii) a cathode conductively connected to the anode, wherein the cathode is physically associated with a second microbial population or an abiotic catalyst, 
 the distance between the anode and cathode is less than 3 cm, 
 there is no proton selective material between the anode and the cathode, and 
 the surface area of the cathode is at least twice the surface area of the anode 
   (b) contacting the wastewater to the anode;   (c) allowing the water to continuously flow with a constant flow of influent through the anode and a constant flow of product across or from the cathode; and   (d) collecting the effluent.   
     
     
         26 . The method of  claim 25 , further comprising the step of
 (e) monitoring the electrical current generated from the reactor; and   (f) adding fresh influent to the system when decreasing electrical current is observed.   
     
     
         27 . The method of  claim 25 , wherein the treatment is demonstrated as a reduction in total suspended solids, biological oxygen demand, methanogenesis, or odor. 
     
     
         28 . The method of  claim 27 , wherein the reduction in total suspended solids is from about 22000 mg/L to about 6600 mg/L in a 10 day period. 
     
     
         29 . The method of  claim 27 , wherein the biological oxygen demand from about 4500 mg/L to about 2250 mg/L in a 5 day residence time. 
     
     
         30 . The method of  claim 27 , wherein the methanogenesis is from about 1.4 ppm to about 0.7 ppm over a 10 day period. 
     
     
         31 . The method of  claim 27 , wherein the odor is from about 21 to about 11 ppm H 2 S over a 5 day period). 
     
     
         32 . A method of generating electricity, the method comprising:
 (a) providing ammonium to a microbial fuel cell comprising:
 (i) an anode; 
 (ii) a cathode electrically coupled to the anode;
 (1) a biofilm comprising a first microbial population physically associated with the anode, wherein the first microbial population are microorganisms that catalyze oxidation of organic carbon compounds in wastewater; 
 (2) a biofilm comprising a second microbial population physically associated with the cathode, wherein the second microbial population are microorganisms that catalyze reduction of an oxidant; and 
 
   (b) generating a biochemical gradient within the microbial fuel cell to produce electricity.   
     
     
         33 . The method of  claim 32 , wherein the microbial population physically associated with the anode enzymatically extract electrons from organic components in the influent and transfer the electrons to the anode electrode. 
     
     
         34 . The method of  claim 32 , wherein the cathode uses cations, protons, or electrons as a source of energy during the reduction of oxygen or other oxidant. 
     
     
         35 . The method of  claim 32 , wherein the second microbial population consume cations or an abiotic catalyst. 
     
     
         36 . The method of  claim 35 , wherein the abiotic catalyst is metal, carbon, graphite-based, platinum, tungsten carbide, cobalt oxide, titanium, manganese(IV)-oxide, molybdenum, tungsten, or a combination thereof. 
     
     
         37 . The method of  claim 32 , wherein the anode comprises graphite, a graphite-doped ceramic, polyaniline. graphite granules, large-pore aerogels, graphite fiber brushes, graphite perforated plates, graphite porous spheres, graphite woven fibers, graphite felt, graphite cloth, or a combination thereof. 
     
     
         38 . The method of  claim 32 , wherein the anode comprises a microporous mesh made of nylon, PTFE or PVDF. 
     
     
         39 . The method of  claim 34 , wherein the oxidant is a nitrite, a sulfate, a fumarate, or a heavy metal. 
     
     
         40 . The method of  claim 32 , wherein the electricity production at high peak demand is about 1 kW/m 3 .