How do we tackle the unprecedented increase in nutrient emissions in the world? How much nitrogen is emitted by agriculture and wastewater treatment? In her presentation at SLU, Professor Tove Larsen from EAWAG, Switzerland analyses the current wastewater treatment situation in various regions in the world. She suggests urine source separation can be part of the solution to address global nutrient emissions. To know more about this and other aspects such as the Blue Diversion Toilet and the Eawag water hub, check out Prof. Larsen’s presentation.Post published by Prithvi Simha
Dr. David Gustavsson, Research Leader at Sweden Water Research loves centralized wastewater treatment plants! He starts his presentation saying…“I really love these plants”. At a symposium filled with people discussing the possibility of taking sanitation off the grid, that’s quite a statement to make. Jokingly, he further comments, “....should I leave now?”. How good are centralized WWTPs in removing unwanted substances? In nutrient removal and recovery? Is there a case to be made for the co-existence or indeed, the integration of urine diversion with the operation of such plants? How will WWTP operations be affected with increased urine diversion at source?
Click here to access Dr. Gustavsson’s presentation to find out more and let us know what you think!Post published by Prithvi Simha
The eThekwini Municipality in the greater Durban region with its 80,000 urine diverting toilets is often highlighted as a success story for dry sanitation. In a recent presentation at SLU, Professor Chris Buckley, Head of the Pollution Research Group at the University of KwaZulu-Natal, South Africa reflected on the eThekwini case study.
Jenna Senecal, Doctoral Candidate at the Environmental Engineering Unit, Department of Energy and Technology will defend her licentiate thesis entitled, Urea stabilisation and dehydration for urine-diverting toilets: System and hygiene evaluation.
When?: 24 October 2017 at 09:00
Where?: Lecture Room S, Ulls hus, Swedish University of Agricultural Sciences, Uppsala
For further information, get in touch with Jenna Senecal at the Department of Energy and Technology, P.O. Box 7032, SE-750 07 Uppsala, Sweden. E-mail: firstname.lastname@example.org
Abstract: Over four billion people are discharging untreated human excreta into the environment without any prior treatment, causing eutrophication and spreading disease. This eutrophication is caused by nutrients found predominantly in urine. If managed adequately, urine can be used as a fertiliser because it contains the same plant nutrients as the fertilisers used to produce the food that people eat. Currently to replace the nutrients removed from fields during harvesting, more fertilisers are being manufactured and applied and ultimately more are being leached into the environment.
The use of human urine as a fertiliser is limited by its low nutrient concentration compared with commercial fertilisers. This study sought to increase the nitrogen (N) concentration (from 0.6 % to >6 %) through dehydration to produce a dry fertiliser of monetary value and where no liquid disposal from the toilet is required. The objective of this thesis was to evaluate a treatment that could stabilise urea and concentrate the urine while retaining >80 % of the NKP. Fresh human urine was added at various intervals to wood ash or biochar to first alkalise and thus inhibit the enzyme urease which catalyses the hydrolysis of urea. The urine was then dehydrated at temperatures of between 35 and 65 °C. A hygiene assessment was undertaken to observe the inactivation of five microorganisms (three indicators: Enterococcus faecalis, MS2 bacteriophage and ΦX 174 bacteriophage; and two pathogens: Ascaris suum and Salmonella enterica sub enterica Typhimurium) at the end of the alkaline dehydration process.
Urine mass was reduced by 95 % during dehydration, while preserving up to 90 % of the N and all the P and K. Ascaris inactivation data was fitted to a non-linear regression model, which estimated that 325 days of storage would be required for a 3 log10 reduction at 20 °C and 9.2 days of storage at 42 °C. The bacteria and bacteriophages were below the detection limit within four days at 20 °C. Just collecting urine separately from faeces provides a 5.2 log10 reduction. The material is concentrated during dehydration which results in a 3.5 log10 reduction overall just from urine-diversion.
This alkaline dehydration system installed in new or already existing toilets would greatly simplify the logistics and costs of storing, transporting and applying urine as a fertiliser. The truly innovative feature is the final product, a dry powder with 7.8 % N, 2.5 % P and 10.9 % K on dry weight, i.e. equivalent to commercial fertilisers. After just four days of storage, the dehydrated medium would meet WHO and USEPA guidelines for unrestricted fertiliser use.
Posted by Prithvi Simha