Phenol Shock Load Research Articles

Simultaneous nitrification and denitrification (SND) bioaugmentation with Pseudomonas sp. HJ3 inoculated for enhancing phenol and nitrogen removal in coal gasification wastewater.

A simultaneous nitrification and denitrification (SND) bioaugmention system with Pseudomonas sp. HJ3 inoculated was established to explore the potential of simultaneous phenol and nitrogen removal in coal gasification wastewater (CGW). When the concentration of influent chemical oxygen demand (COD) and total phenols (TPh) was 1,765.94 ± 27.43 mg/L and 289.55 ± 10.32 mg/L, the average removal efficiency of COD and TPh at the stable operating stage reached 64.07% ± 0.76% and 74.91% ± 0.33%, respectively. Meanwhile, the average removal efficiency of NH4 +-N and total nitrogen (TN) reached 67.96% ± 0.17% and 57.95% ± 0.12%, respectively. The maximum SND efficiency reached 83.51%. Furthermore, SND bioaugmentation performed with good nitrification tolerance of phenol shock load and significantly reduced toxic inhibition of organisms. Additionally, the microbial community analysis indicated that Pseudomonas sp. HJ3 was the predominant bacterium in the SND bioaugmentation system. Moreover, the indigenous nitrogen removal bacteria such as Thauera, Acidovorax and Stenotrophomonas were enriched, which further enhanced the nitrogen removal in the SND bioaugmentation system. The results demonstrated the promising application of SND bioaugmentation for enhancing simultaneous phenol and nitrogen removal in CGW treatment.

Stability of continuous and fed batch sequential anaerobic–anoxic–aerobic moving bed bioreactor systems at phenol shock load application

ABSTRACTThe stability of two sequential moving bed bioreactor systems operated in anaerobic–anoxic–aerobic continuous moving bed bioreactor (CMBR: R1–R2–R3) and semi-continuous fed batch moving bed bioreactor (FMBR: B1–B2–B3) modes was assessed for phenol shock load (PSL) applications in the presence of thiocyanate and ammonia. Both the systems were exposed to 3000 mg phenol/L (PSL-I) and 3500 mg phenol/L (PSL-II) for 3 days each from initial 2500 mg phenol/L without any intermediate concentration at 6 days HRT (hydraulic retention time). The effect of PSL-I on R1 was reversible within 10–12 days. At PSL-II, R1 required 2 days stop of feed for stability and resumed removal efficiency of phenol (15%) and COD (3%). R2 remained robust to sustain both PSLs and recovered within 15 days from peak influent concentrations of 1727 mg phenol/L (removal: 67%) and 324 mg SCN−-/L (removal: 68–70%). In B1, effluent COD increased by 2%, though effluent phenol decreased by 3% than the pre-shock condition after PSL-I exposure. B2 acted similar to R2 when exposed to PSLs. The effect of PSL-I on R3 and B3 was negligible. However, at PSL-II R3 became vulnerable for nitrification, whereas phenol, COD and SCN− removal remained unaffected. In B3, PSL-II caused a decrease in phenol, SCN− and NH+4−N removal. In B3, stop of feed for 4 days also did not improve nitrification. The performance of the CMBR system was better than that of the FMBR system for organic shock load exposure in the presence of multiple pollutants.

Illumina MiSeq sequencing reveals long-term impacts of single-walled carbon nanotubes on microbial communities of wastewater treatment systems

In this study, phenol wastewater treatment systems treated with different concentrations of single-walled carbon nanotubes (SWCNTs) (0–3.5g/L) were exposed to phenol and carbon nanotubes (CNTs) shock loadings to investigate the long-term impacts of SWCNTs on microbial communities. Phenol removal remained high efficiency (>98%) in SWCNTs-treated groups but decreased in non-treated group (85.1±1.9%) when exposed to high concentration of phenol (500mg/L). However, secondary dosing of SWCNTs in SWCNTs-treated groups would decrease the phenol removal efficiency. Illumina MiSeq sequencing revealed that the diversity, richness and structure of microbial communities were shifted under phenol shock loading, especially under high phenol concentration, but not under CNTs shock loading. In response to phenol and CNTs shock loadings, Rudaea, Burkholderia, Sphingomonas, Acinetobacter, Methylocystis and Thauera became dominant genera, which should be involved in phenol removal. These results suggested that a proper amount of SWCNTs might have positive effects on phenol wastewater treatment systems.

Application of immobilized and granular dried anaerobic biomass for stabilizing and increasing anaerobic bio-systems tolerance for high organic loads and phenol shocks

This study focuses on the stability and tolerance of continuous-flow bioreactors inoculated with anaerobic methanogens in three different configurations: (R1) dried granular biomass immobilized in PAC-enriched hydrophilic polyurethane foam, (R2) dried granular biomass, and (R3) wet granular biomass. These systems were tested under two different organic loading rates (OLR) of 6.25 and 10.94 (gCOD/(Lreactor∗d)), using a glucose-based synthetic mixture. The effect of an instantaneous shock load of phenol (5g/L for three days), and of phenol inclusion in the feed (0.5g/L) were also tested. At the lower OLR, all reactors performed similarly, however, increasing the OLR lead to a significant biomass washout and failure of R3. Biomass in R1 was more tolerant to phenol shock load than R2, though activity was recovered in both systems after about one month. PAC provided protection and shortened the adaptation time for 0.5g/L phenol that continuously was fed.

Biological removal of phenol from saline wastewater using a moving bed biofilm reactor containing acclimated mixed consortia.

In this study, the performance of an aerobic moving bed biofilm reactor (MBBR) was assessed for the removal of phenol as the sole substrate from saline wastewater. The effect of several parameters namely inlet phenol concentration (200–1200 mg/L), hydraulic retention time (8–24 h), inlet salt content (10–70 g/L), phenol shock loading, hydraulic shock loading and salt shock loading on the performance of the 10 L MBBR inoculated with a mixed culture of active biomass gradually acclimated to phenol and salt were evaluated in terms of phenol and chemical oxygen demand (COD) removal efficiencies. The results indicated that phenol and COD removal efficiencies are affected by HRT, phenol and salt concentration in the bioreactor saline feed. The MBBR could remove up to 99% of phenol and COD from the feed saline wastewater at inlet phenol concentrations up to 800 mg/L, HRT of 18 h and inlet salt contents up to 40 g/L. The reactor could also resist strong shock loads. Furthermore, measuring biological quantitative parameters indicated that the biofilm plays a main role in phenol removal. Overall, the results of this investigation revealed that the developed MBBR system with high concentration of the active mixed biomass can play a prominent role in order to treat saline wastewaters containing phenol in industrial applications as a very efficient and flexible technology.

Influence of operational parameters on nitrogen removal efficiency and microbial communities in a full-scale activated sludge process

To improve the efficiency of total nitrogen (TN) removal, solid retention time (SRT) and internal recycling ratio controls were selected as operating parameters in a full-scale activated sludge process treating high strength industrial wastewater. Increased biomass concentration via SRT control enhanced TN removal. Also, decreasing the internal recycling ratio restored the nitrification process, which had been inhibited by phenol shock loading. Therefore, physiological alteration of the bacterial populations by application of specific operational strategies may stabilize the activated sludge process. Additionally, two dominant ammonia oxidizing bacteria (AOB) populations, Nitrosomonas europaea and Nitrosomonas nitrosa, were observed in all samples with no change in the community composition of AOB. In a nitrification tank, it was observed that the Nitrobacter populations consistently exceeded those of the Nitrospira within the nitrite oxidizing bacteria (NOB) community. Through using quantitative real-time PCR (qPCR), nirS, the nitrite reducing functional gene, was observed to predominate in the activated sludge of an anoxic tank, whereas there was the least amount of the narG gene, the nitrate reducing functional gene.

Treatment of phenolic wastewater in an anaerobic fixed bed reactor (AFBR)—Recovery after shock loading

An anaerobic fixed bed reactor (AFBR) was run for 550 days with a mixed microbial flora to stabilize synthetic wastewater that contained glucose and phenol as main carbon sources. The influent phenol concentration was gradually increased from 2 to 40 mmol/l within 221 days. The microbial flora was able to adapt to this high phenol concentration with an average of 94% phenol removal. Microbial adaptation at such a high phenol concentration is not reported elsewhere. The maximum phenol removal observed before the phenol shock load was 39.47 mmol/l or 3.7 g phenol/l at a hydraulic retention time (HRT) of 2.5 days and an organic loading rate (OLR) of 5.3 g/l.d which amounts to a phenol removal rate of ca. 15.8 mmol phenol/l.d. The chemical oxygen demand (COD) removal before exposing the reactor to a shock load corresponded with phenol removal. A shock load was induced in the reactor by increasing the phenol concentration from 40 to 50 mmol/l in the influent. The maximum phenol removal rate observed after shock load was 18 mmol/l.d at 5.7 g COD/l.d. But this was not a stable rate and a consistent drop in COD and phenol removal was observed for 1 week, followed by a sharp decline and production of fatty acids. Recovery of the reactor was possible only when no feed was provided to the reactor for 1 month and the phenol concentration was increased gradually. When glucose was omitted from the influent, unknown intermediates of anaerobic phenol metabolism were observed for some time.

Evaluation of an Anaerobic Granule Biosensor for Upset Early Warning Detection

In this study a porous pot reactor was used to simulate an activated sludge stage and an anaerobic granule biosensor (AGB), as an upset early warning system for activated sludge treatment process, was configured in a down-flow mode with a side-stream of the influent wastewater fed to the top. The hydraulic retention time (HRT) for the porous pot and AGB systems was 12 hours and 6 hours, respectively. The influent was made up of synthetic wastewater. In the first group of toxic loading tests, the prepared cupric chloride solutions were separately injected into both the porous pot and AGB systems at six different concentrations (5, 10, 15, 20, 30, and 45mg Cu/L), and phenol solutions were used at four different concentrations (10, 20, 30, and 45mg phenol/L) in the second group of toxic loading tests. In addition, a control study was included for reference. The porous pot reactor and AGB were monitored for pH, ORP, COD, solids, and ammonia concentrations following a simulated toxic event. The COD removal efficiency of porous pot system decreased dramatically in response to the addition of Cu and phenol. The greatest decrease in COD removal efficiency was from 92% to 52% at a Cu concentration of 30 mg/L, and was from 98% to 76% at a phenol concentration of 45mg/L. The longest time of COD removal efficiency continuous decreasing was 23 hours at a Cu concentration of 45 mg/L, and 7 hours at a phenol concentration of 10mg/L. Similar to the response in COD removal, the ammonia removal efficiency decreased significantly after the Cu shock loading. As the porous pot reactor was challenged with the Cu or phenol shock load, the AGB received an equivalent dose. The most sensitive parameter reflecting the toxic shock load in the AGB was the ORP. The ORP changed more rapidly and uniformly than the pH over both the range of Cu concentrations and phenol concentration tested. The shortest response time to

Response of pulse phenol injection on an anaerobic–anoxic–aerobic system

The performance of a three-stage suspended growth continuous system consisting of anaerobic–anoxic–aerobic reactors was evaluated after injection of a pulse phenol shock load in the anaerobic reactor. The synthetic feed contained phenol, cyanide, thiocyanate and ammonia-nitrogen. Anaerobic reactor required 22 days to regain its previous cyanide removal efficiency and the reactor achieved a new steady state in terms of phenol removal. The anoxic reactor achieved its previous phenol and the thiocyanate removal efficiency in seven to nine days. In the aerobic reactor, nitrification was severely inhibited due to the washout of nitrifying bacteria. The aerobic reactor was the most sensitive in terms of phenol shock load in the three-stage system.

Stable augmentation of activated sludge with foreign catabolic genes harboured by an indigenous dominant bacterium.

Comamonas sp. rN7 is a phenol-degrading bacterium that represents the dominant catabolic population in activated sludge. The present study examined the utility of this bacterium for establishing foreign catabolic genes in phenol-digesting activated sludge. The phc genes coding for phenol hydroxylase and its transcriptional regulators of C. testosteroni R5 were integrated into the chromosome of strain rN7. The specific phenol-oxygenating activity of a resultant transformant designated rN7(R503) was three times higher than the activity of strain rN7, and the phc genes were stably inherited by rN7(R503) grown in a non-selective laboratory medium. Inoculation of phenol-acclimatized activated sludge with rN7(R503) resulted in a high phenol-oxygenating activity and improved resistance to phenol-shock loading compared to sludge inoculated with either no cells, rN7 or R5. Quantitative competitive polymerase chain reaction (PCR) showed that the phc genes were retained in the rN7(R503)-inoculated sludge at a density of more than 108 copies per ml of mixed liquor for more than 35 days, whereas those in the R5-inoculated sludge disappeared rapidly. No transfer of the phc genes to other indigenous populations was apparent in the rN7(R503)-harbouring sludge. From these results, we concluded that the phenol treatment of the activated sludge was enhanced by the phc genes harboured by the rN7(R503) population. This study suggests a possible bioaugmentation strategy for stably utilizing foreign catabolic genes in natural ecosystems.

Biological mechanisms involved in bioflocculation disturbances caused by phenol

The research focused on the clarification of the biological mechanisms involved in bioflocculation disturbances caused by the exposure of suspended biomass to phenol shock loading. Contact experiments were performed by exposing activated sludge biomass under non-growth and under growth conditions to various concentrations of phenol. Severe damage to the settling of biosolids could be observed, especially under growth conditions. The following mechanisms were found to be relevant to these disturbances: (1) cellular lysis resulted in the creation of a fraction of small particles (<0.45 μm) which could be considered as mostly cellular debris, due to their sizes and especially to their lack of oxygen uptake; (2) lower hydrophobicity of biosolids surfaces, could be a result of the amphiphatic properties exerted by the phenol molecule, as well as by the cellular components released to the aqueous phase by lysis and by membranal damage; (3) the exposure to phenol caused the unbinding of exocellular biopolymers from biosolids surfaces to the aqueous solution, creating conditions of poor settleability resulting from: (a) bioflocs characterized by low density; (b) dispersion of small biofloc fragments; (c) dispersion of single cells; (4) phenol loading was found able to lower the cellular ATP concentrations and this inhibition of the cellular bioenergetics could also be a factor impairing the boflocculation process.

Response to various shock loadings of the constant recycle‐sludge‐concentration activated‐sludge process

AbstractThe stability of the model of a completely mixed activated‐sludge process holding the recycle sludge concentration, XR, as a system constant subjected to pH, temperature, potassium cyanide, and phenol shock loading was investigated. Soft‐drink bottling wastewater was used and maintained at 1000 mg/liter chemical oxygen demand (COD). The hydraulic ratio and recycle sludge concentration were maintained at 0.3 and 7000 mg/liter, respectively. An initial dilution rate of ¼ hr−1 was maintained for pH and temperature shock loading, with ¼ and ⅛ hr−1 for KCN shock loading and ¼, ⅛, and \documentclass{article}\pagestyle{empty}\begin{document}$\frac{1}{16}$\end{document} hr−1 for phenol shock loading. It was found that the present system could handle pH shock loading as low as 4.0 and as high as 10.4 without any serious disruption of biological solid concentration and filtrate COD. At pH 4.0 shock loading, filamentous organisms were predominant. Temperature shock loading could be handled from 23 to 36°C without any leakage of effluent filtrate COD. At 46°C temperature shock, a 14 hr period was required to recuperate to the new steady state and provided only 85% of COD removal efficiency. For KCN (50 mg/liger) and phenol (85 mg/liter) shock loading, the dilution rates should be lower than \documentclass{article}\pagestyle{empty}\begin{document}$\frac{1}{16}$\end{document} hr−1 in order to shorten the transient period and improve the effluent quality. Biological kinetic constants included cell yield value, maximum growth rate, and the saturation constant, which was varied with the qualitative shock applied.