Inhibition effect of swine wastewater heavy metals and antibiotics on anammox activity

Abstract

The feasibility of anaerobic ammonium oxidation (anammox) process to treat wastewaters containing antibiotics and heavy metals (such as the liquid fraction of the anaerobically digested swine manure) was studied in this work. The specific anammox activity (SAA) was evaluated by means of manometric batch tests. The effects of oxytetracycline, sulfathiazole, copper and zinc were studied. The experimental data of the short-term assays were fitted with an inhibition model to identify the half maximal inhibitory concentration (IC(50)). After 24 h exposures, IC(50)-values equal to 1.9, 3.9, 650 and 1,100 mg L(-1) were identified for copper, zinc, sulfathiazole and tetracycline respectively. The effect of prolonged exposure (14 days) to oxytetracycline and sulfathiazole was studied by means of repeated batch-assays. Anabolism and catabolism reactions were active during the inhibition tests indicating that anammox bacteria could grow even in the extreme conditions tested. Considering the average concentrations expected in swine wastewaters, the inhibitors studied do not seem to represent a problem for the application of the anammox process. However, in order to verify the effect of these compounds on the growth of anammox bacteria, continuous culture experiments could be conducted.

Short-Term and Long-Term Inhibitory Effects of Copper on Anammox Process

“…Lotti et al [33] reported the heavy metal concentration which causes the 50% decrease in Anammox activity(IC50) as 1.9 mg L −1 , on the other hand Zhang et al reported that the short-term inhibition IC50 level as 32.5 mg L −1 and Van del Rio et al [38] found for the same level of inhibition concentration as 19.3 mg L −1 . The variability of the results may be explained by the different Anammox species that take arole in the conversions.…”

“…Although some of the heavy metals are fundamental for microbial cell production, they are also common inhibitors for biological processes in high concentrations. Although some specific heavy metals have been studied Cd(II), Cu(II), Ni(II), Zn(II), Hg, Pb, Ag on Anammox activity [24][25][26][27][28][30][31][32][33][34], there has been little agreement on inhibition doses of these heavy metals. However, the experimental data are rather controversial, and there is no general agreement about inhibitory concentrations.…”

Do antibiotics have environmental side-effects? Impact of synthetic antibiotics on biogeochemical processes

“…The duration of the exposure of colistin used by Bressan et al (2013) on ammonia-oxidizing bacteria was 5 h. Schmidt et al (2012) already stated that Binhibition of cell division or protein biosynthesis may be observed only after test duration of several days.^The importance of incubation time was also shown in the BSubstrate Induced Respiration (SIR)^test of Thiele-Bruhn and Beck (2005); no effect was observed after 4 h, whereas respiration was inhibited by both oxytetracycline and sulfapyridine after 24 h. Short-term experiments that are shorter than the growth rate of the targeted bacteria, therefore, explore the effect of the antibiotic on enzyme activity. Studies regarding short-term effects (Bressan et al 2013;Costanzo et al 2005;Hou et al 2015;Katipoglu-Yazan et al 2013) can be contrasted to long-term effect studies: from days (Ahmad et al 2014;Alighardashi et al 2009;Conkle and White 2012;Fountoulakis et al 2004;Hou et al 2015;Ingvorsen et al 2003;Thiele-Bruhn and Beck 2005;Yamamura et al 2014), weeks (Campos et al 2001;Cui et al 2014;Klaver and Matthews 1994;Kotzerke et al 2008;Kotzerke et al 2011;Lotti et al 2012;Rico et al 2014;Roose-Amsaleg et al 2013;Toth et al 2011;Underwood et al 2011;Wunder et al 2013;Yan et al 2013), months (Fernandez et al 2009;Hansen et al 1992;Näslund et al 2008;Rosendahl et al 2012), to a year (442 days by Schmidt et al 2012). Conducting experiments for extended time periods is difficult because degradable antibiotics, as well as nutrients, can be quickly consumed unless continuously added …”

“…Two studies (Fernandez et al 2009;Lotti et al 2012) investigated the effect of antibiotics on the anammox process exploring both acute and chronic effects of four different antibiotics (oxytetracycline, tetracycline hydrochloride, sulfathiazole, and chloramphenicol). Only therapeutic concentrations (100-1000 mg/L) were tested in WWTP sludges.…”

A novel strategy for accelerating the recovery of an anammox reactor inhibited by copper(II): EDTA washing combined with biostimulation via low-intensity ultrasound

“…To date, we are aware of few publications concerning the inhibitory impact of Cu(II) on anammox activity [8,[10][11][12][13]. These publications indicate that AnAOB are highly sensitive to Cu(II).…”