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Poo is gold (WUR)
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Resource recovery from black water
Thesis summary:
New sanitation concepts are based on separation at source of household wastewater
streams, e.g. into grey water and black water (faeces and urine), and have a large
potential to recover the important resources energy, nutrients and water. A promising
treatment system for highly concentrated black water, collected with vacuum toilets,
was designed, consisting of anaerobic treatment followed by struvite precipitation for
phosphorus recovery and autotrophic nitrogen removal. A UASB (Upflow Anaerobic
Sludge Blanket) reactor removed on average 78% of the influent organic load at a
relatively short hydraulic retention time (HRT) of 8.7 days. The methane production
was 1.8 m3 CH4 per m3 of black water, which can be converted to 56 MJ/p/y as
electricity and 84 MJ/p/y as heat by combined heat and power (CHP). Autotrophic
nitrogen removal was selected to remove the nitrogen from black water in a two
reactor nitritation-anammox process. Partial nitritation of the ammonium in the
UASB effluent was successfully achieved in a continuous system operated at 34 °C
and at 25 °C. The main fraction, 85 to 89%, of total nitrogen could be removed in the
anammox reactor at 35 °C and 25 °C, however only after the calcium concentration of
the black water of 42 mg/L was increased with an additional 39 mg/L for better
granulation and biomass retention. The strong global warming gas nitrous oxide
(N2O) was emitted in the two reactor nitritation-anammox process and more
research is needed to elucidate the mechanisms of N2O emission. Phosphorus was
conserved for 61% in the UASB effluent and precipitation of phosphate as struvite can
result in a recovery of 0.22 kgP/p/y, representing 10% of the global artificial
phosphorus fertilizer production. The remaining part of the phosphorus ended up in
the UASB sludge, mainly due to precipitation (39%) because of a low dilution and a
high pH in the black water. This sludge may be used as a phosphorus-enriched
organic fertilizer, provided it is safe with respect to heavy metals, pathogens and
micro-pollutants. Although black water is very complex matrix, it was possible to
detect the presence of a selection of hormones and pharmaceuticals. The presence of
persistent micro-pollutants, which are not susceptible for biodegradation, makes the
application of advanced physical and chemical treatment unavoidable. More research
is needed with respect to the presence and removal of heavy metals, pathogens and
micro-pollutants in new sanitation concepts.
campus full address
Wageningen UR, hoofdgebouw
Droevendaalsesteeg 4
6708 PB Wageningen
the Netherlands
country
Netherlands
contact person/researcher/expert
Marthe Sophie de Graaff
key words
new sanitation, separation at source, resource recovery, black water, anaerobic treatment, UASB reactor, partial nitritation, anammox, nitrous oxide, phosphorus, struvite, hormones, pharmaceuticals, LC MS/MS
creator of profile
Klaas Metselaar
email contact person
klaas.metselaar@wur.nl
institution(s)
Wageningen
visibility of the part "ii innovation profile"
Public
origins of the idea
Research institution
spatial scale
Lab
primary use of project
Mixed use
sectors of innovation
Water, Waste
upscaling potential
Lab
type of innovation
Technical, Agriculture
innovation status
Concepts/Ideas/Designs
time to market
2 – 3 years