Abstract
State regulatory and other agencies identified that nitrogen loading from the wastewater treatment plants (WWTPs) discharging around its periphery has adversely affected the San Francisco Bay (SFB) water quality. Here we consider the upscaling of the zeolite-anammox process treatment to nitrogen removal from relatively high-ammonia content (~500 NH3-N mg/L) anaerobic-digester (AD) filtrate to facilitate reductions in WWTP nitrogen discharge. First, by operating a 210 L barrel reactor as a trickling filter with a 10% by volume initial bio-zeolite seeding fraction, we found that 6–8 weeks elapsed before the anammox activity became apparent. Moreover, the 10-mm zeolite aggregate reactor achieved an 89% ammonia-N removal compared to the 85% achieved by the 20-mm aggregate. We then evaluated the performance of the trickling-filter design in a 68 m3 Baker tank nearly filled with 20-mm zeolite aggregate seeded with bio-zeolite at about 1.5% by volume. At an average inflow of 42 m3/day, about one year elapsed before achieving adequate anammox activity and acceptable treatment. Unfortunately, inadequate suspended solids pre-treatment of the AD filtrate resulted in clogging problems in the Baker tank reactor, so we evaluated aerobic-anaerobic cycling within the tank and then operated it (anaerobically) as a nitrate-scavenging tank. In the final anaerobic operational stage, nitrate effluent concentrations were <1 mg/L, perhaps due to dissimilatory nitrate reduction to ammonium by the anammox process, but ammonia removal fractions were only about 47%.
Highlights
As discussed in a companion paper (Collison and Grismer [1]), San Francisco Bay (SFB) estuary water quality is adversely affected by nitrogen loading from wastewater treatment plant (WWTP)discharges on the Bay periphery (SFEI [2])
Analysis of the changing effluent ammonia- and nitrate-N concentrations from the barrel reactors study enabled the assessment of the time required for the anammox bacteria to become fully functional in terms of ammonia removal while gaining insight into the effects of the zeolite particle size on the ‘maturation’ process and the likely clogging problems associated with AD filtrate Total Suspended Solids (TSS) loading
In this second paper, considering the upscaling of the zeolite-anammox nitrogen removal process to commercial applications, we investigated the treatment of relatively high-ammonia content (~500 NH3 -N mg/L) anaerobic-digester (AD) filtrate to a discharge project goal of
Summary
As discussed in a companion paper (Collison and Grismer [1]), San Francisco Bay (SFB) estuary water quality is adversely affected by nitrogen loading from wastewater treatment plant (WWTP)discharges on the Bay periphery (SFEI [2]). As discussed in a companion paper (Collison and Grismer [1]), San Francisco Bay (SFB) estuary water quality is adversely affected by nitrogen loading from wastewater treatment plant (WWTP). There is an increasing regulatory scrutiny of WWTP nitrogen discharges intensifying WWTP interest in developing cost-effective methods to reduce nitrogen loading in their discharge. The ammonium-rich filtrate is returned to the WWTP head works for further treatment where it can increase the ammonium loading to the WWTP treatment train by as much as 30%, despite the very small contribution (1–5%) to the total WWTP flow (Lackner et al [3]).
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