Manufacturing bio-bricks using microbial induced calcium carbonate precipitation and human urine.

In this study, we investigated the use of a natural process called microbial induced calcium carbonate precipitation (MICP) to 'grow' bio-bricks using the urea present in human urine. We first collected fresh urine and stabilized the urine with calcium hydroxide. This prevented any significant loss of urea which allowed it to then be used for the MICP process. We used Sporosarcina pasteurii bacteria to help drive the MICP process. The bacteria degraded the urea present in the urine to form carbonate ions which then combined with the calcium ions present in the urine solution to produce calcium carbonate. This calcium carbonate was then used as a bio-cement to glue loose sand particles together in the shape of a brick. The maximum compressive strength we obtained for a bio-brick was 2.7 MPa which compares well with conventionally made bricks. We successfully showed that human urine can be used to manufacture bio-bricks thus offering an additional use of human urine.