More Like this

1. Effects of external recirculation on a two‐stage mainstream anaerobic‐anammox treatment system

   https://doi.org/10.1002/wer.1019  

   Li, Xiaojin ; He, Zhen ( February 2019 , Water Environment Research)

   Nitritation‐anammox treatment can be a potentially energy‐ and resource‐efficient technology for treating mainstream wastewater. However, the issue of nitrate residue from anammox treatment remains to be addressed. Herein, external recirculation of the anammox effluent to a hybrid anaerobic reactor (HAR), which was also to provide a continuous flow with lowCOD/N for the nitritation‐anammox reactor, was employed to decrease the residue compounds. The recirculation ratio of 50% was observed to be the optimal to achieve the best overall performance with potential savings in energy demand. Specifically, in the operation scenario ofR = 50%, the highestCODremoval of ~90% by theHARwas achieved. Meanwhile, the lowestCOD/NH₄⁺‐N ratio of ~2.0 in theHAReffluent ensured the lowest observedNO₃⁻‐N/NH₄⁺‐N ratio of ~14% in the nitritation‐anammox reactor. These results have demonstrated the feasibility of applying external recirculation for nitrate residue removalviadenitrification in the anaerobic pretreatment stage.

   Nitritation‐anammox treatment is an attractive method for mainstream wastewater treatment.

   Nitrate residue from anammox processes contributes to total nitrogen in the final effluent.

   Recirculation of anammox effluent to an anaerobic reactor can decrease nitrate residue.

   A recirculation ratio of 50% results in a low COD/NH₄⁺ratio of 2 that benefits the subsequent anammox.

    

   more » « less
2. Evaluation of anammox biocathode in microbial desalination and wastewater treatment

   https://doi.org/https://doi.org/10.1016/j.cej.2018.02.088  

   Bahareh Kokabian, Veera Gnaneswar ( June 2018 , Chemical engineering journal)

   This study presents the use of an autotrophic microorganism, Anammox bacteria, as a sustainable biocatalyst/biocathode in microbial desalination cells (MDCs) for energy-positive wastewater treatment. We report the first proof of concept study to prove that anammox mechanism can be beneficial in MDCs to provide simultaneous removal of carbon and nitrogen compounds from wastewater while producing bioelectricity. A series of experiments were conducted to enrich and evaluate the anammox mechanism and the process performance in continuous, fed-batch mode conditions. Coulombic efficiency of MDCs and nitrite and ammonium removal of wastewater increased in successive batch studies. A maximum power density of 0.092 Wm−3 (or a maximum current density of 0.814 A m−3) with more than 90% of ammonium removal was achieved in this system. We calculated the Nernst potential for the nitrite reduction in the anammox biocathode chamber and compared with experimental values. Sequential removal of carbon and nitrogen compounds in anode and cathode chambers respectively, was also evaluated. Further, the inhibition effect of high nitrogen concentrations and the variations in microbial community profiles, especially, anammox presence was studied at different carbon and ammonia concentrations. Experimental studies and microbial community analysis are presented in detail. 

   more » « less
3. Reduction in urban water use leads to less wastewater and fewer emissions:analysis of three representative U.S. cities

   https://doi.org/10.1088/1748-9326/ab8dd8  

   Gursel, Aysegul Petek ; Chaudron, Camille ; Kavvada, Ioanna ; Horvath, Arpad ( July 2020 , Environmental Research Letters)

   Electricity consumption and greenhouse gas (GHG) emissions associated with wastewater flows from residential and commercial water use in three major cities of the United States are analyzed and compared for the period 2010–2018. Contributions of unit wastewater treatment processes and electricity sources to the overall emissions are considered. Tucson (Arizona), Denver (Colorado), and Washington, DC were chosen for their distinct locations, climatic conditions, raw water sources, wastewater treatment technologies, and electric power mixes. Denver experienced a 20% reduction in treated wastewater volumes per person despite a 16% increase in population. In Washington, DC, the reduction was 19%, corresponding to a 16% increase in population, and in Tucson 14% despite a population growth of 3%. The electricity intensity per volume of treated wastewater was higher in Tucson (1 kWh m⁻³) than in Washington, DC (0.7 kWh m⁻³) or Denver (0.5 kWh m⁻³). Tucson’s GHG emissions per person were about six times higher compared to Denver and four times higher compared to Washington, DC. Wastewater treatment facilities in Denver and Washington, DC generated a quarter to third of their electricity needs from onsite biogas and lowered their GHG emissions by offsetting purchases from the grid, including coal-generated electricity. The higher GHG emission intensity in Tucson is a reflection of coal majority in the electricity mix in the period, gradually replaced with natural gas, solar, and biogas. In 2018, the GHG reduction was 20% when the share of solar electricity increased to 14% from zero in 2016. In the analysis period, reduced wastewater volumes relative to the 2010 baseline saved Denver 44 000 MWh, Washington, DC 11 000 MWh and Tucson 7000 MWh of electricity. As a result, Washington, DC managed to forgo 21 000 metric tons of CO_2-eqand Denver 34 000 metric tons, while Tucson’s cumulative emissions increased by 22 000 metric tons of CO_2-eq. This study highlights the variability observed in water systems and the opportunities that exist with water savings to allow for wastewater generation reduction, recovering energy from onsite biogas, and using energy-efficient wastewater treatment technologies.

    

   more » « less
4. A microbial desalination process with microalgae biocathode using sodium bicarbonate as an inorganic carbon source

   https://doi.org/https://doi.org/10.1016/j.ibiod.2018.04.003  

   Thomas J. Arana, Veera Gnaneswar ( May 2018 , International biodeterioration & biodegradation)

   This research investigates a novel platform for an energy-yielding wastewater treatment and desalination scheme in which the organic matter present in wastewater is purposely fed to the exoelectrogenic bacteria to produce bioelectricity in a three-compartment bioelectrochemical system called photosynthetic microbial desalination cell (PMDC). The role of an inorganic carbon source in the microalgae biocathode was studied. Addition of sodium bicarbonate (NaHCO3) increased power production, microalgae growth and desalination rate. A power density of 660 mW/m3 was measured which is about 7.5 times higher than the PMDCs without NaHCO3. Desalination rate was more than 40% after 72 h. Overall, the process could be energy-positive while producing 4.21 kWh per m3 of wastewater treated including desalination energy savings and microalgae biomass energy potential. 

   more » « less
5. UTEP–EPW university–utility partnership: Concentrate enhanced–recovery reverse osmosis process for high water recovery from silica‐saturated desalination concentrates

   https://doi.org/10.1002/wer.1176  

   Tarquin, Anthony ; Walker, William Shane ; Delgado, Guillermo ; Bustamante, Angel ( July 2019 , Water Environment Research)

   Since the 1970s, The University of Texas at El Paso and El Paso Water have had a synergistic university–utility partnership, and in 2002, we began a sequence of investigations of enhanced recovery of water from silica‐saturated reverse osmosis concentrate: (a) two‐pass nanofiltration (NF) and reverse osmosis (RO) treatment, (b) lime softening for silica removal, (c) vibratory shear enhanced processing (VSEP), (d) continuous‐flow seawater RO treatment of brackish RO concentrate, and finally (e) high‐recovery concentrate enhanced‐recovery reverse osmosis (CERRO) process. Studies funded by El Paso Water, Texas Water Development Board, U.S. Bureau of Reclamation, and WateReuse Research Foundation were conducted at the Kay Bailey Hutchison (KBH) Plant in El Paso and the Brackish Groundwater National Desalination Research Facility in Alamogordo, NM, and showed that as much as 88% of the water could be recovered from silica‐saturated KBH concentrate using the CERRO process. Full‐scale implementation of the CERRO process at well sites in El Paso has resulted in 70%–75% recovery of RO concentrate with a specific energy consumption of 1.23 kWh/m³(4.6 kWh/kgal) and total estimated cost of approximately $0.59/m³($2.25/kgal). Cost‐effective high‐recovery desalination technologies such as CERRO are essential for drought‐proof water supply in arid cities such as El Paso.

   This two‐decade UTEP‐EPW research partnership was sustained by a long‐term commitment to research and consistent financial support from EPW.

   Universities can collaborate to leverage utility funding toward larger external grant funding to advance research and development in a win–win partnership.

   The high‐recovery CERRO process was developed through multiple phases of concentrate management research, which would not have been possible without long‐term research commitment and risk tolerance from EPW.

   CERRO systems are being implemented at full scale in El Paso to recover water from silica‐saturated RO concentrate at an estimated specific energy consumption of 1.23 kWh/m³(4.6 kWh/kgal) and total amortized cost of $0.59/m³($2.25/kgal).

    

   more » « less