Manure,which is an essential part of the agricultural cycle, possesses
a potential water and nutrient source essential for crop production.
Therefore, animal slurry can be treated to recover both water and
nutrient-rich streams. Konieczny et al. [86] recovered water from pig
slurry utilizing an integrated systemconsisting of centrifugation followed
by a two-step UF followed by NF. They tested four different plant
configurations (Fig. 8). UF and NF treatment of manure showed promising
results for water production, with quality in the drinking water
range for some components. However, the amount of ammonium in
the produced water was too high for drinking water use. Nevertheless,
for irrigation water ammonium is a valuable nutrient source.
Guo and Jin [87] investigated anaerobically digested cattle manure
treatment with RO pretreated by UF. It was observed that ammonia
was rejected with a rate of 77.1% at the first pass and only 54.2% at the
second pass, most probably due to the pH increase of the RO feed.
However, the concentration of NH4
+ in the final permeate was around
63 mg/l from the initial 836 mg/l. Rejection of other species such as K,
Na and Cl was observed to be as high as 90%. The decrease in ions
such as sodium and chloride boost the potential of irrigation in which
the nitrogen content will not cause oversupply.
Concerning the cost of the reclaimed water through membranebased
operations, energy consumption and then the cost in wastewater
treatment is lower than that of desalination. Raffin et al. [88]
analyzed nine different membrane wastewater treatment plants
based on UF/MF and RO technology. The energy demand of the analyzed
wastewater plants was rather broad, ranging from 0.69 to
2.3 kWh/m3 permeate. In comparison, energy demand for desalination
based on the Ashkelon desalination plant is above 3.9 kWh/m3,
which is 25–70% higher compared to the wastewater plants analyzed
in this study. For the best functioning wastewater treatment plant this
is a relatively high saving that can be achieved when irrigation water
is produced from wastewater compared to desalination. However,
energy demands are still higher than conventional treatment (0.3–
0.9 kWh/m3) [88].