Identification of urine scale problems in urinals and the solution using rainwater

Abstract

Water-saving urinals, such as waterless and low-flush urinals, have a great potential for water conservation by using 0 ∼ 0.8 l/flush compared with ordinary urinals, which use 2 ∼ 4 l/flush. However in some cases, water-saving urinals are not desirable because of technical problems, such as urine scale formation which makes the urinal dirty and blocks pipes. Also, some cultures do not allow the use of waterless urinals because of their notion of cleanliness. In this paper, factors causing urine scale formation have been identified from laboratory tests on pure urine and several types of flushing water. Some meaningful solutions for managing and solving urine scale problems have been suggested. In particular, the results show that mixing urine with seawater or high salinity groundwater will increase the potential of urine scale formation by increasing total dissolved solids (TDS) and pH. However, using rainwater for urinal flushing can significantly reduce the TDS and pH. These findings could support the use of water-saving toilets in Islamic societies by ensuring that the cleanliness of urinals can still be achieved.