Heterotrophic–autotrophic sequential system for reductive nitrate and perchlorate removal

Abstract

Nitrate and perchlorate were identified as significant water contaminants all over the world. This study aims at evaluating the performances of the heterotrophic-autotrophic sequential denitrification process for reductive nitrate and perchlorate removal from drinking water. The reduced nitrate concentration in the heterotrophic reactor increased with increasing methanol concentrations and the remaining nitrate/nitrite was further removed in the following autotrophic denitrifying process. The performances of the sequential process were studied under varying nitrate loads of [Formula: see text] at a fixed hydraulic retention time of 2 h. The C/N ratio in the heterotrophic reactor varied between 1.24 and 2.77 throughout the study. Nitrate and perchlorate reduced completely with maximum initial concentrations of [Formula: see text] and 1000 µg/L, respectively. The maximum denitrification rate for the heterotrophic reactor was [Formula: see text] when the bioreactor was fed with [Formula: see text] and 277 mg/L methanol. For the autotrophic reactor, the highest denitrification rate was [Formula: see text] in the first period when the heterotrophic reactor performance was low. Perchlorate reduction was initiated in the heterotrophic reactor, but completed in the following autotrophic process. Effluent sulphate concentration was below the drinking water standard level of 250 mg/L and pH was in the neutral level.

An Overview of Electron Acceptors in Microbial Fuel Cells

“…Among the treatment alternatives, biological reduction is a cost effective method (Ucar et al, 2015a,b, 2016). Reduction of ${\text{CIO}}_4^{-}$ is shown as illustrated in Equation (25) (Ye et al, 2012).…”

Biological Reduction of Acid Red 14 by Elemental Sulfur and Methanol-Based Reactors

“…However, sulfurbased reactor's performance remained stable (Figure 3). 15 10 0 0 0 0 *: In the 7 th period, dye house effluent was treated which contained 5 mg/L AR14.…”

“…Despite its many advantages, as far as the author's knowledge, the use of sulfur-based autotrophic reactors are limited to the removal of heavy metals [9], [12], bromate [13] perchlorate [13], [14] and mainly nitrate [15] from drinking water due to its clean nature. Therefore, it is necessary to investigate the applicability of elemental sulfur-based reactors to various fields, especially to the textile industry.…”

Environmental effects of sulfur-based autotrophic and methanol based heterotrophic denitrification processes

“…Sülfatın kontrol altına alındığı bu çalışmanın ardından aynı ekip ototrofik denitrifikasyonun alkalinite ihtiyacını aynı sisteme metanol dozlayarak heterotrofik denitrifikasyonda üretilen alkalinite ile sağlamışlardır [15]. Tek reaktörde gerçekleştirilen bu süreç daha sonraları heterotrofik -ototrofik sıralı kolon sistemlerde gerçekleştirilmiş [9], [21] ve heterotrofik kolon -ototrofik membran sıralı sistemi ile 145 mg/L NO3 --N in tam giderimi sağlanmıştır [22]. Çalışmalar, heterotrofik ile ototrofik denitrifikasyon sistemlerinin kombinasyonunun iki prosese ait dezavantajlarını (asidite ve sülfat üretimi) minimize ettiğini göstermektedir.…”