Multiple-stage activated-char filtration

Less than 1% of the worlds water is considered freshwater. Population growth and intensive use in cities and agro industrial activities threatens the depletion of this resource in many parts of the world. This depletion poses many major social and economic concerns. As a result, efforts have been made to develop economically viable technologies to make potable water from seawater or brackish water resources. Today, 40% of desalination is accomplished through Reverse Osmosis (RO) technology (Greenlee, 2009). While RO has proven to be an effective technology, almost 40% of the operating costs involved in the process are energy-related (SNL, 2003). A multi stage activated char filtration with Capacity Deionization (CDI) technology is herein proposed as a novel approach for water filtration. The removal of organic and inorganic compounds can be achieved in a series of activated char modules to selectively remove contaminants in a more inexpensive and environmentally friendly manner. By using electric energy on a porous media (e.g. activated char), ions from salt can be retained. Thus activated char and CDI can produce fresh water while potentially using significantly less energy than RO (Porada, 2013). Biochar produced through the pyrolysis technology can enhance the adsorption of anions, cations or remove organic molecules (in similar fashion to activated carbon). Coupling this technology with the use of CDI in an electrode configuration will enhance the adsorption of smaller and more challenging ions. The pyrolysis process can be tailored to produce biochar to match specific equirements for both cathode and anode electrode configurations. Successful use of biochar in the CDI process would not only reduce process production costs, but would also further enhance sustainability. Biochar is principally composed of structurally resilient carbon. It reduces CO2 emissions from the manufacturing process compared to traditional activated carbon due to its renewable precursor feedstock and the slow decay of its recalcitrant carbon structure. Current water desalination techniques require large energy inputs and high capital costs. Reverse osmosis is not suited for small scale applications and requires expensive energy recovery systems. Commercial Applications and Other Benefits: The use of multiple-stage activated char with capacitive deionization can provide important reductions in energy use for the desalination in small scale and remote water purification facilities. Compared to current membrane deionization technologies, this new technology includes significantly less infrastructure, capital costs and complexity for the development and operation.