The use of source separated human urine as fertilizer is one of the major suggestions of the new sanitation concept ECOSAN. Urine is rich in nitrogen, phosphorus and potassium which act as plant nutrients, however its salinity is high for agricultural and landscape purposes. Moreover, characteristics change significantly throughout storage where salinity increases to higher values as the predominant form of nitrogen shifts from urea to ammonium. Transferring nitrogen in human urine onto the natural zeolite clinoptilolite and using the subsequently recovered ammonium from the exhausted clinoptilolite for agricultural/landscape purposes is suggested as an indirect route of using urine in this work. Results reporting the outcome of the proposed process together with characterization of fresh and stored urine, and preliminary work on the application of the product on the landscape plant Ficus elastica are presented. Up to 97% of the ammonium in stored urine could be transferred onto clinoptilolite through ion exchange and about 88% could be recovered subsequently from exhausted clinoptilolite, giving an overall recovery of 86%. Another important merit of the suggested process was the successful elimination of salinity. Preliminary experiments with Ficus elastica had shown that the product, i.e. clinoptilolite exhausted with ammonium, was compatible with the synthetic fertilizer tested.
Collection of wastewater in segregated streams is one of the new concepts in domestic wastewater management. One such stream is yellow water which is mainly human urine. Direct use of this richest fraction in terms of nutrients on plants as fertilizer is one of the recommendations as the final end use. Indirect use of urine as fertilizer may also be exercised after various modes of processing. One of those is processing with clinoptilolite to transfer plant nutrients onto the zeolite and then to recover them subsequently. One of the significant factors in this process is the initial nutrient loading with which clinoptilolite is charged. This paper aims to investigate the transfer of ammonium and potassium from source-separated urine onto clinoptilolite, concentrating upon surface concentrations attained and removal efficiencies under various initial ammonium loadings. The results have indicated that variations in initial loading have no significant effect in terms of removal efficiencies up to 10 mg NH(4) (+)/g clinoptilolite. Highly acceptable efficiencies could be attained up to 15 mg NH(4) (+)/g clinoptilolite after which the efficiency goes down as initial loading is increased. Overall, increased initial loadings result in higher final surface concentrations but decreased removal efficiencies.
Source-separated human urine may be used as a source of fertilizers indirectly through processing with clinoptilolite. The suggested form of fertilizer is clinoptilolite loaded with plant nutrients from urine, where nitrogen and phosphorus will be released upon contact with water. Triggered by the need for handling high concentrations remaining in the liquid phase to be disposed of, this paper aims to present the option of improving the residual nutrient quality through stagewise processing with clinoptilolite, while investigating any improvement in nutrient removal. Two sets of experiments, stagewise operation under (i) constant loadings and (ii) variable loadings in each stage, are discussed. Stagewise operation has been observed to be successful for attaining reduced residual liquid phase concentrations as well as improvements in nitrogen recovery as compared to single-stage operation. Comparing constant and variable stagewise loadings, the final concentration is 10 times lower with variable loadings. The latter is comparable to a level found in only 1% of conventional domestic wastewater volume. Stagewise operation was beneficial from the standpoint of both additional nutrient recovery and for residuals control, with more pronounced benefits for attaining higher quality residual liquid phase concentrations to be disposed of.
Human urine is a rich source of plant nutrients and yellow water, i.e., source separated human urine, contains the greatest portion of nitrogen, phosphorus and potassium in regular domestic wastewater. Hence yellow water constitutes a highly concentrated liquid phase of those plant nutrients. Adsorption/ion exchange is one of the physicochemical processes which have a high potential for nutrient recovery from human urine. Motivated by the successful results obtained for nitrogen through processing with the natural zeolite clinoptilolite, it was the aim of this work to investigate the success of the process in terms of phosphorus recovery. Within this context, removal of phosphorus from human urine through contacting with clinoptilolite and its release from the surface of the exhausted clinoptilolite, which is suggested as an alternative fertilizer, upon contacting with tap water to mimic irrigation, and rain water to mimic precipitation events were examined. Surface concentrations of up to 1.33 mg P/g clinoptilolite could be attained under the experimental conditions employed, with indications of a likely increase in surface concentrations through increasing the initial loading. The results have revealed that 95-99 % of phosphorus in the liquid phase could be transferred onto clinoptilolite, and 88-99 % of this could be recovered to provide an overall recovery of 83-94 %. This indicates that when urine is processed with clinoptilolite, not only nitrogen but also phosphorus is removed from the solution and upon contacting the exhausted clinoptilolite with water, not only nitrogen but also phosphorus will be released and be made available to plants.
It had previously been shown that ammonium selective natural zeolite clinoptilolite may be used successfully as an ion exchanger for ammonium removal and nitrogen control from domestic wastewater. The process had been reported to be acceptable either by itself alone or as an upgrade. In this work, the possibility of using clinoptilolite for ammonium removal from fertilizer production wastewater was investigated. The fertilizer plant under consideration was rather a non-typical one with a lower ammonium strength than what is normally expected, and a variable effluent concentration. Batch experiments were performed to assess the capacity of clinoptilolite towards ammonium removal from an industrial wastewater at two different pHs. Flow experiments for the characterization of system behavior under continuous feeding conditions at different contact times were conducted for breakthrough analysis. Both real and simulated fertilizer wastewater samples were investigated and the results have shown that the real one may successfully be represented by the simulated one. Experimental results have shown that surface capacities exceeding 14 mg ammonium g(-1) clinoptilolite could be attained, complete removal of ammonium may be achieved with empty bed contact times of 10 min or higher and ion exchange with clinoptilolite could be used successfully to comply with the effluent standards given for the fertilizer plant.
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