NH4-N Removal Through Nitrification and Hydrogenotrophic Denitrification in Simple Attached Growth Reactors

The Status of Domestic Water Demand: Supply Deficit in the Kathmandu Valley, Nepal

“…High levels of arsenic, ammonia, and iron in the deep groundwater, and nitrates and E. coli in shallow groundwater, exceeding World Health Organization (WHO) guidelines, have been reported in the Kathmandu Valley [14][15][16][17]. A study by Sakamoto et al [18] showed that almost all water from the rivers and shallow wells in the core valley was not suitable for drinking because of the presence of E. coli, and only 29% of the deep tube wells had drinkable water [18].…”

“…However, treatment of groundwater at the household level, including disinfection, filtration, and boiling before consumption (particularly during the wet season), is recommended to deal with microbial contamination. For the treatment of physicochemical contamination, the simple-in-operation, low cost, and energy efficient ammonia and nitrate removal system developed by Khanitchaidecha et al [17] could be used at the household or community scale. For iron removal, aeration, sedimentation and filtration before denitrification could be applied, as suggested by Khanitchaidecha et al [23].…”

Hydrogenotrophic Denitrification of Groundwater Using a Simplified Reactor for Drinking Water: A Case Study in the Kathmandu Valley, Nepal

“…The development of alternative removal processes, especially for nitrogen species, is therefore necessary. A promising reactor for NH 4 + -N removal from groundwater, which is low-cost, low-maintenance, and has excellent performance, has been developed [18][19][20]. However, the system is capable of removing only NH 4 + -N through oxidation of NH 4 + -N to NO 3 − -N by nitrifying bacteria, and the NO 3 − −N produced during nitrification remains of great concern [20].…”

“…Recently, hydrogenotrophic denitrification (HD), which is a type of autotrophic denitrification, has drawn much attention as a promising technology for nitrate removal from groundwater [19,21,[23][24][25][26][27][28][29][30][31][32][33][34][35][36] because it offers certain advantages over heterotrophic denitrification systems. First, biomass generation can be reduced, thereby reducing clogging and the cost of post-treatment [33].…”

“…This leads to high costs for infrastructure and operation, frequent cleaning, post-treatment requirements, and high maintenance. In contrast, simplified HD systems, for example, using an attached growth reactor, can be well suited for application in developing countries owing to their user-friendliness [19,21,23]. To date, most research on the development of HD reactors for groundwater has been conducted in the laboratory using synthetic groundwater, and little information is available on the application of HD for raw groundwater treatment and the behavior of HD systems under on-site conditions.…”