SANDEC WATER AND SANITATION IN DEVELOPING COUNTRIES ING UN-HABITAT ENVIRONMENTAL ENGINEERING NEPAL Struvite Recovery from Urine at Community Scale in Nepal Final Project Report Phase I March 2009 Basil Gantenbein Raju Khadka Duebendorf, Switzerland Kathmandu, Nepal Eawag: Swiss Federal Institute of Aquatic Science and Technology Struvite Recovery from Urine at Community Scale in Nepal (STUN) - Final Project Report Phase I Basil Gantenbein & Raju Khadka Eawag, Water and Sanitation in Developing Countries (Sandec) Postfach 611, 8600 Dübendorf, Switzerland Tel: +41 (0)44 823 52 86 Fax: +41 (0)44 823 53 99 www.eawag.ch / www.sandec.ch UN-Habitat Water for Asian Cities Programme Nepal Pulchowk, PO Box 107, Kathmandu, Nepal Tel: +977 1 55 42 816 Fax: +977 1 55 39 877 www.unhabitat.org STUN is a joint collaboration project of Eawag (Swiss Federal Institute of Aquatic Science and Technology) and UN-Habitat Water for Asian Cities Programme Nepal (The United Nations Human Settlement Programme). March 2009 © Swiss Federal Institute of Aquatic Science and Technology (Eawag), 2009 Contents Contents ............................................................................................................................ i Abstract ............................................................................................................................ ii Figures ..............................................................................................................................iii Tables ...............................................................................................................................iii Annex ............................................................................................................................... iv Abbreviations ................................................................................................................... vi 1 Introduction ............................................................................................................... 1 1.1 Project Design .................................................................................................................. 2 2 Study Area ................................................................................................................. 4 2.1 EcoSan Overview Kathmandu Valley ................................................................................. 4 2.2 Visited Sites...................................................................................................................... 5 2.3 Siddhipur ......................................................................................................................... 7 3 Production and Market Environment ......................................................................... 1 3.1 Predominant Soil Types and Soil Fertility ........................................................................... 1 3.2 Fertilizer Market Overview ............................................................................................... 3 3.3 Local Agricultural Practices ............................................................................................... 5 4 Struvite Production Process Inputs ............................................................................13 4.1 Urine .............................................................................................................................. 13 4.2 Magnesium .................................................................................................................... 28 5 Struvite Production Process Outputs .........................................................................36 5.1 Struvite .......................................................................................................................... 36 5.2 Processing Effluent ......................................................................................................... 41 6 Management and Economics ....................................................................................43 6.1 Urine Value .................................................................................................................... 43 6.2 Estimated Struvite Value ................................................................................................ 47 6.3 Community Scale Struvite Production in Siddhipur .......................................................... 49 6.4 Management Approaches for Struvite Production ........................................................... 50 7 Conclusions ...............................................................................................................52 References .......................................................................................................................54 Annex ..............................................................................................................................57 - i - Abstract Struvite production at a community scale within a peri-urban settlement of Kathmandu is possible. Urine Community Approx. 350 liters of urine can be collected per Social acceptance of struvite is high in the adult household member and year with an Newar community. Concerns are indicated EcoSan toilet. about the acceptance in other, higher casts (Brahmins, Chetris). The collected urine shows nutrient concentra- tions at the lower range of expected values. Observed interest and enthusiasm for struvite within the community of Siddhipur are remark- The presently available usage options for able. source separated urine are suboptimal. It is es- timated that for approx. 60% of the collected The rural character of the community poses urine the utility value could be improved. questions whether promotion of direct applica- tion is preferable over struvite precipitation. Whereas half of the farmers prefer struvite Magnesium precipitation others prefer direct application Magnesium products are scarce in Nepal. Sourcing is difficult but possible. Due to the Economics nonexistent demand prices are comparably high. The current local nutrient value of urine is es- timated to approx. 250 NRp·m-3 (3.70 CHF). At present magnesium sulphate is the product 20% of this value can be fixed as struvite, 80% of choice. Bittern and locally quarried magne- remain in the processing effluent. site might have a potential for the future. The effluent it of major concern as the major part of nutrients cannot be precipitated as Agriculture struvite. It is unlikely that struvite production becomes economically feasible unless viable The present availability of industrially produced and efficient usage/treatment options are mineral fertilizer is good. Organic fertilizers are available for the effluent. sparse as cattle are rare and composting and EcoSan toilets are the only available sources. The present magnesium input costs are of the same order as the likely price struvite can Whereas nitrogen is applied sufficiently phos- achieve on the market. Additional labour and phorous and potassium are assumed to be defi- processing costs are not included yet. cient. A full-scale community wide struvite production Struvite, having a phosphate content of 29%, scheme could at present generate approx. 170 could become a welcome additional source of kg struvite per year with an estimated value of phosphorous. 5’000-7’000 NRp (75-100 CHF). The practical reactor set-up and operation as well as further research in project phase II will bring addi- tional and more assured results. - ii - Figures Figure 1: Overview of topics of interest STUN Phase I ............................................................................................ 3 Figure 2: Overview of Kathmandu Valley and the visited communities ................................................................. 5 Figure 3: Arial view of Siddhipur V.D.C ................................................................................................................... 8 Figure 4: A traditional saaga composting pit .......................................................................................................... 9 Figure 5: Nepalese soil analysis results (pH, organic matter, nitrogen, phosphorous, potassium) ........................ 1 Figure 6: Soil acidity map of Bhaktapur District ...................................................................................................... 2 Figure 7: FGD Participants ..................................................................................................................................... 25 Figure 8: Household Survey .................................................................................................................................. 25 Figure 9: Nutrient fixation by struvite precipitation ............................................................................................. 41 Figure 10: Institutional Arrangement of Siddhipur user Committee .................................................................... 50 Tables Table 1 Major and micro plant nutrients ................................................................................................................ 2 Table 2 Functions and deficiency symptoms of various plant nutrients ................................................................. 2 Table 3 Available fertilizers in Siddhipur ................................................................................................................. 4 Table 4 Basic farm characteristics ..........................................................................................................................