A post graduate student of civil engineering at the University of Cape Town (UCT) has developed a natural process that allows bio-bricks to be created from human urine.
Signalling a paradigm shift in waste recovery, the world's first bio-brick grown from human urine was unveiled recently by Suzanne Lambert.
The bio-bricks are developed through a natural process called microbial carbonate precipitation, similar to the way seashells are formed.
Lambert's supervisor Dr Dyllon Randall, a senior lecturer in water quality engineering, explained that loose sand was colonised with bacteria that produced an enzyme called urease, which broke down the urea in urine while producing calcium carbonate through a complex chemical reaction. This cemented the sand into any shape, including for the first time, a rectangular building brick.
The outcome of several months of research and laboratory testing by Lambert and civil engineering honours student Vukheta Mukhari, the bio-bricks are also environment-friendly as they are made in moulds at room temperature, compared to regular bricks, which are kiln-fired at high temperatures and produce vast quantities of carbon dioxide.
The strength of the bio-bricks would be based on the end application. If a client wanted a stronger brick, the bacteria would be allowed to make it stronger by 'growing' it for longer.
Lambert’s brick uses real human urine for the first time, with the process producing nitrogen and potassium as by-products, which are important components of commercial fertilisers.
Though urine accounts for less than 1 percent of domestic waste water (by volume), it contains 80 percent of the nitrogen, 56 percent of the phosphorus and 63 percent of the potassium of this waste water.
Some 97 percent of the phosphorus present in the urine can be converted into calcium phosphate, the key ingredient in fertilisers that underpin commercial farming worldwide and also a material in short supply. The fertilisers are produced as part of the phased process used to produce the bio-bricks.
The process begins with collecting urine in novel fertiliser-producing urinals and making a solid fertiliser. The remaining liquid is used in the biological process to grow the bio-brick. With the urine completely converted into three useful products, the bio-brick offers a zero waste solution.
The next phase of research will explore how to optimise the manufacturing process so that it can lead to profit; the logistics of urine collection and transport to a resource recovery; and social acceptance.