Waterless urinals (WLU) save water, energy and use urine as resource ( Image courtesy: R Sakthivel)
This resource book is a guide on ‘waterless urinals’ (WLU), that will assist individuals, builders, engineers, architects, and policy makers in promoting them. It presents the benefits of harvesting urine for reuse through waterless urinals and urine diverting toilets.
Schematic drawing showing functioning of conventional and waterless urinals
This ecological sanitation method does not require water for flushing, thus saving between 56,800 litres to 1, 70,000 litres of water per urinal per year. It includes the following sections:
Advantages of waterless urinals and reuse of urine
Water is employed to control odour in the conventional urinals whereas waterless urinals utilise odour control mechanisms like sealant liquid or membrane traps and biological blocks. A comparative analysis of popular odour traps with regard to cost, maintenance, replacement and clogging frequency is given in a tabular form. Steps for installation of these WLU ,storage and maintenance details are elaborated in the guide book.
Innovative urinal designs
The following innovative urinal designs can be promoted as per the feasibility and budget available:
Green Waterless Urinal (GWU): A low‐cost onsite urine application model suitable for sites where adequate space is available and the number of users are limited. Urine collected is diverted to a plant bed of Canna Indica and Ficus planted around the urinal.
Urine diverting toilets
These facilitate separation of urine from faeces and wash‐water and its advantages are as follow:
Urine harvesting for agriculture
Urine harvested by constructing waterless urinals and urine diverting toilets can be utilised as a resource in agriculture depending on the quantity produced and the quality. However precautions need to be taken while using urine as a fertilizer.
Manually operated reactor for recovery of struvite (Image source: EAWAG)
Some of the methods used are direct application, deep Injection, drip irrigation, struvite (a fertiliser in solid form, obtained by adding magnesium chloride to urine) and composting (urine can be added to compost to enrich its nutrient values and also for quickening the composting process).
Challenges and the way forward