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.

Within the context of Ecological Sanitation (ECOSAN), human urine has been the subject of research and practice as a potential fertilizer in the recent years. Although quite a lot had been done with original undiluted urine with promising outcomes, not much appears in the literature which concentrates on dilute solutions of urine. This is important because unless waterless toilets are employed, urine will be diluted with flush water in actual use. In this work, dilute solutions of urine are investigated with emphasis on the recovery of plant nutrients. A natural zeolite namely clinoptilolite was loaded with nitrogen, phosphorus, and potassium as an indirect route of processing urine. The results have revealed that hydrolysis is completed in shorter times in dilute samples. Clinoptilolite could successfully remove plant nutrients from all dilute solutions. Nitrogen could be recovered up to 86% with higher efficiencies at higher concentrations in general. Recovery of orthophosphates increases with increasing concentration to reach 96%, however, potassium could not be recovered. The preliminary experiments with grass have revealed that nutrient loaded clinoptilolite was as effective as chemical fertilizers while direct application of original and diluted solutions of urine had shown inferior yields.

Providing clean water at relevant quality and quantity is a challenge that regulatory authorities have to face in metropolitan cities that seem to develop at their limits of sustainability. Istanbul strives to face such a challenge for its population of over 10 million, through six surface water resources. Two approaches of classification for the reservoirs are presented, one based on current regulations and an alternative based on a more detailed classification. The results have shown that nutrient control is the primary issue, and one of the reservoirs has already exceeded the limits of being eutrophic, one is at mesotrophic conditions, and the remaining four are at the limit of being eutrophic, indicating the significance of making the correct decision and taking pertinent measures for management and control. It has been observed that the only mesotrophic resource, which also has the best general quality class, has no industry and a very low population density, whereas the one that is already eutrophic is also the one with the lowest quality class, has the highest population density, and has the greatest percentage of urban land use within its watershed.

Ion exchange using clinoptilolite for the removal of peak concentrations of ammonia from domestic wastewater as a second stage, by itself and in combination with sand filters, is evaluated. It is observed that there is no significant loss of capacity of clinoptilolite when placed in sand filters. All three configurations studied are successful in the removal of peak concentrations of ammonia, and hence can be used as a polishing unit, to comply with the demands of stringent standards. Among those investigated, the combined scheme, with clinoptilolite and aerated sand filters where biological activity is enhanced, is found to be the most effective provided that sufficient time for the development of nitrifiers are allowed. The performance loss of the clinoptilolite was observed to be 10% after 10 cycles of regular operation and regeneration.

Water is supplied in the Greater Istanbul Metropolitan Area from the surface water of six main reservoirs. The present land use in the catchment areas of the reservoirs indicates that the area devoted to agricultural activities and to forests and meadows varies between 73 and 97% and that only a minor percentage, 1-26%, is devoted to settlements and industries. In contrast to the land use profile, the current environmental evaluation of the catchment areas reveals that point sources dominate over diffuse sources. However, this trend is expected to be reversed in the near future, making diffuse sources and control of fertilizers and pesticides the most significant issue. Pollutant loads regarding pesticides and fertilizers are calculated from unit loads based on area. These pollutants are observed to have a negative impact on water quality in terms of eutrophication and toxicity. In this paper, the status of fertilizers and pesticides are addressed and some protective measures for reducing the impact of agricultural pollutants in the reservoirs are recommended.