Preparation and characterization of a decentralized modular yellow water nutrient recovery system

The peculiarity of human urine as a resource, in terms of ethical and cultural considerations, and human perception, demands the development of a highly decentralized modular system, to enable the feasibility of the emerging concept of nutrient recovery in this regard. Consequently, a modular reactor, with packed bed of granular Gastropod shell (GS) was constructed for nutrient recovery from yellow water and the operational parameters were derived in simulated and pilot studies. Prior to the design of the modular reactor, both the raw and calcined GS were screened in a batch reactor for nutrient fraction recovery (i.e. total phosphorus (TP) and total nitrogen (TN)). The TP recovery was more favorable than the TN, but the TN recovery was the rate determining step. Despite the low TN capture efficiency of the reactor, the hydrolysis of the urea fraction that promotes nitrogen loss from yellow water was greatly impeded. The system showed higher selectivity for the nutrient fraction than the other constituents of the human urine, as manifested in the high residual COD and creatinine values in the treated yellow water. The volume of yellow water treated and the nutrient recovery capacity of the modular reactor were HRT dependent. A diminution in the nutrient recovery efficiency was observed in the pilot study, when compared with the simulated studies of the same HRT.