Mineralizing urban net-zero water treatment: Field experience for energy-positive water management

Abstract

An urban net-zero water treatment system, designed for energy-positive water management, 100% recycle of comingled black/grey water to drinking water standards, and mineralization of hormones and other organics, without production of concentrate, was constructed and operated for two years, serving an occupied four-bedroom, four-bath university residence hall apartment. The system comprised septic tank, denitrifying membrane bioreactor (MBR), iron-mediated aeration (IMA) reactor, vacuum ultrafilter, and peroxone or UV/HO advanced oxidation, with 14% rainwater make-up and concomitant discharge of 14% of treated water (ultimately for reuse in irrigation). Chemical oxygen demand was reduced to 12.9 ± 3.7 mg/L by MBR and further decreased to below the detection limit (<0.7 mg/L) by IMA and advanced oxidation treatment. The process produced a mineral water meeting 115 of 115 Florida drinking water standards that, after 10 months of recycle operation with ∼14% rainwater make-up, had a total dissolved solids of ∼500 mg/L, pH 7.8 ± 0.4, turbidity 0.12 ± 0.06 NTU, and NO-N concentration 3.0 ± 1.0 mg/L. None of 97 hormones, personal care products, and pharmaceuticals analyzed were detected in the product water. For a typical single-home system with full occupancy, sludge pumping is projected on a 12-24 month cycle. Operational aspects, including disinfection requirements, pH evolution through the process, mineral control, advanced oxidation by-products, and applicability of point-of-use filters, are discussed. A distributed, peroxone-based NZW management system is projected to save more energy than is consumed in treatment, due largely to retention of wastewater thermal energy. Recommendations regarding design and operation are offered.

Modeling the energy consumption of potable water reuse schemes

“…In contrast to the centralized reuse schemes explored in this study, decentralized potable reuse has the potential to reduce the energy consumption required for water conveyance and domestic water heating as well as enable almost complete local recycling of wastewater ( Englehardt et al., 2016 ). Based on pilot-scale testing and modeling, a 1 MGD decentralized plant was predicted to more than offset the primary energy it requires for water treatment (at a SEEC of 2.98 kWh/m 3 , similar to the 2.76 kWh/m 3 this study predicts for IPR with RO plus conventional wastewater treatment) by retaining heat and thus reducing the primary energy required for domestic water heating ( Wu and Englehardt, 2016 ). While energy-positive water reuse is a promising concept, small-scale systems have additional challenges related to robustness and the need for operator intervention, as shown in the development of a potable reuse system to meet the water needs of 120 people at Davis Station, Antarctica ( Zhang et al., 2017 ).…”

“…The use of blending limits the size of advanced treatment plants, particularly for small-blending-ratio DPR installations, which tends to raise the cost of recycled water ( Guo et al., 2013 ) and can limit the efficiency of critical components, such as RO pumps. Alternatively, although they are beyond the scope of this study, decentralized reuse schemes that minimize blending represent a promising approach to achieving “net-zero water” by treating wastewater where it is created, avoiding potential quality losses associated with blending, and retaining thermal energy ( Englehardt, Wu, Bloetscher, Deng, du Pisani, Eilert, Elmir, Guo, Jacangelo, LeChevallier, Leverenz, Mancha, Plater-Zyberk, Sheikh, Steinle-Darling, Tchobanoglous, 2016 , Wu, Englehardt, 2016 ).…”

Wastewater Treatment in Remote Arctic Settlements

“…In the state of Alaska (USA), it was suggested to implement a closed water supply cycle with wastewater reuse for irrigation and domestic purposes. Such a scheme includes primary treatment, a membrane bioreactor, electrocoagulation, physicochemical oxidation, and filtration [14]. This scheme was able to significantly reduce the COD-index to 0.7 mg/L.…”

Análisis de falla operacional de un sistema hidroneumático en instalación hospitalaria

“…Cualquier discusión de las limitaciones de presión en el lado de la succión requiere de la comprensión del término Carga Neta Positiva en la Succión (NPSH) [6][7][8][9][10]. Además, existen dos términos de carga positiva en la succión, la Carga Neta Positiva en la Succión requerida (NPSHR), la cual requiere el equipo de bombeo para prevenir la cavitación y es usualmente suministrado por el fabricante, y la Carga Neta Positiva en la Succión disponible (NPSHd) la cual depende fundamentalmente de las condiciones de operación y de la geometría del sistema de conducción.…”