Tetrazolium Chloride-dehydrogenase Activity Research Articles

Enhancing nitrogen removal from domestic sewage with low C/N ratio using a biological aerated filter system with internal reflux-coupled intermittent aeration

Biological aerated filter (BAF) systems with internal reflux-coupled intermittent aeration enhance the removal of nitrogen pollutants from low-C/N ratio domestic sewage. Two experimental systems with the same specifications, a BAF system with internal reflux-coupled intermittent aeration (system A) and a traditional BAF system (system B) was constructed to explore the efficiency of nitrogen removal. Overall, the nitrification in system B was higher than that in system A due to the influence of aeration model. Conversely, the system A can use the alternating anoxic (DO<0.5 mg·L−1) and aerobic (DO around 1 mg·L−1) environment to obtain better Total Nitrogen (TN) removal rate of 21.56 mg·(kg·h)−1 in the bottom of 30–70 cm zone of the reactor by combining reflux nitrate with influent COD. This section had a low specific oxygen uptake rate but high triphenyl tetrazolium chloride-dehydrogenase activity, indicating that the system enhanced nitrogen removal by denitrification in this section. The 16 S rDNA high-throughput sequencing analysis showed that the diversity index of system A was higher than that of system B. The abundance of microorganisms involved in denitrification was higher in the 30–50 cm zone of system A, mainly in the phylum (10.63%) and the phylum Bacillus (32.05%), indicating that system A was used for denitrification through nitrate reflux and intermittent aeration.

Removal of artificial sweeteners and their effects on microbial communities in sequencing batch reactors

Concern is growing over contamination of the environment with artificial sweeteners (ASWs) because of their widespread existence in wastewater treatment plants (WWTPs). To evaluate ASWs removal and the effect on activated sludge, acesulfame (ACE), sucralose (SUC), cyclamate (CYC) and saccharin (SAC) were introduced individually or in mixture to sequencing batch reactors (SBRs) in environmentally relevant concentrations (100 ppb) for 100 days. Comparisons between ACE removal in a full-scale WWTP and in lab-scale SBRs were conducted. Results showed that CYC and SAC were completely removed, whereas SUC was persistent. However, ACE removal in lab-scale SBRs was significantly greater than in the full-scale WWTP. In SBRs, chemical oxygen demand (COD), ammonia nitrogen (NH4+-N) and total nitrogen (TN) removal appeared unchanged after adding ASWs (p > 0.05). Adenosine triphosphate (ATP) concentrations and triphenyl tetrazolium chloride-dehydrogenase activity (TTC-DHA) declined significantly (p < 0.05). The mixed ASWs had more evident effects than the individual ASWs. Microbial community analyses revealed that Proteobacteria decreased obviously, while Bacteroidetes, Chloroflexi and Actinobacteria were enriched with the addition of ASWs. Redundancy Analysis (RDA) indicated ACE had a greater impact on activated sludge than the other ASWs.

Impact of preozonation on the bioactivity and biodiversity of subsequent biofilters under low temperature conditions—A pilot study

The combination of preozonation and subsequent biological granular activated carbon (O3/BAC) filtration is well known as a promising method for the removal of many pollutants. Temperature and nutrients are the dominant factors in external conditions to influence the biological communities. To explore the influence of preozonation under low temperature, the factors such as dissolved oxygen (DO), dissolved organic carbon (DOC) and NH 4 + -N were analyzed from the sampling ports every week; triphenyl tetrazolium chloride-dehydrogenase activity (TTC-DHA) and the nitrifying activity were detected along the bed height of biofilter at four levels (10, 40, 70 and 110 cm) on the 90th, 110th, and 130th day; microbial community, based on 16S rRNA gene-denaturing gradient gel electrophoresis (DGGE), was monitored on the 130th day of the operation. The observed microbial property showed that preozonation had a positive influence on bioactivity, biomass and nitrifying activity. Community analysis showed no significant difference on the biodiversity of nitrifying bacteria between the parallel filters in the inlet end based on the method employed. This result showed that biofilters’ performance is not correlated well with microbial biodiversity. The elevated functionality in O3/BAC filters can be a result of increased microbial activity, which was promoted by preozonation.

Enhancement of anammox activity by addition of compatible solutes at high salinity conditions

The enhancement effect of compatible solutes on anammox activity under salinity stress was investigated. Glycine betaine (GB) was the most effective in alleviating salt toxicity, although all the compatible solutes (GB, trehalose and ectoine) were found to be valid. Acclimation potential of anammox biomass under salinity of 30g/L increased significantly with GB addition. The recovery time in the reactor with GB addition (RB) (49days) accompanied by a more stable stoichiometric ratio was 2.65 times shorter than in the control reactor (RC) (130days). After 49days, the extracellular polymeric substances and the tetrazolium chloride-dehydrogenase activity were 217.9mg/gVSS and 38.7μgTF/gVSS/h in RB, 1.86 times lower and 3.17 times higher than the levels in RC, respectively. RB possessed evident superiority in the aspects of microbial population proportion. And thus, compatible solutes addition was regarded as one of the feasible solution to counteract saline inhibition on anammox.

Measuring the activity of heterotrophic microorganism in membrane bioreactor for drinking water treatment

In order to quantify the activity of heterotrophic microorganism in membrane bioreactor (MBR) for drinking water treatment, biomass respiration potential (BRP) test and 2,3,5-triphenyl tetrazolium chloride–dehydrogenase activity (TTC–DHA) test were introduced and modified. A sludge concentration ratio of 5:1, incubation time of 2h, an incubation temperature that was close to the real operational temperature, and using a mixture of main AOC components as the substrate were adopted as the optimum parameters for determination of DHA in drinking water MBR. A remarkable consistency among BDOC removal, BRP and DHA for assessing biological performance in different MBRs was achieved. Moreover, a significant correlation between the BRP and DHA results of different MBRs was obtained. However, the TTC–DHA test was expected to be inaccurate for quantifying the biomass activity in membrane adsorption bioreactor (MABR), while the BRP test turned out to be still feasible in that case.

Effects of temperature and feed strength on a carrier anaerobic baffled reactor treating dilute wastewater

A carrier anaerobic baffled reactor (CABR), containing hollow-sphere bamboo carriers, was used to examine theeffects of organic and temperature shock loads for a constant hydraulic retention time. The relationships among themacroscopic observables (pH, COD and SS), catabolic intermediates (VFA) and microcosm alternation (TTC–DHA)were studied. A slight fluctuation in pH was observed, ranging from 6.5 to 7.5 throughout the experiments. TheCABR had a COD removal efficiency of 91% with an effluent suspended solids (SS) of 15 mg L −1 at 28°C and a feedstrength of 600 mg L −1 chemical oxygen demand (COD). The reactor could run steadily without souring due to thevolatile fatty acids (VFA) production (<150 mg L −1) and low VFA/alkalinity ratio (<0.23), although the effluent VFAconcentration increased with decreasing operational temperature. For a substrate low in nutrient, the microorganismsconverted the limited substrate into acetate to supply the essential nicotinamide adenine dinucleotide for cellularsynthesis. The tetrazolium chloride–dehydrogenase activity (TTC–DHA) of the attached biomass was higher thanthat of flock biomass at low feed concentration, whereas the result was the opposite at high feed concentration.Microorganisms with lower activity but higher shock resistance were dominant in the first chamber. Therefore, theCABR had high shock resistance and adaptability irrespective of temperature and feed strength.

Study on the Modified triphenyl tetrazolium chloride – dehydrogenase activity (TTC-DHA) Method in Determination of bioactivity in the up-flow aerated bio-activated carbon filter

The study applied triphenyl tetrazolium chloride-dehydrogenase activity (TTC-DHA) method to detect the activities of attached biofilm on bio-activated carbon (BAC) samples in the up-flow aerated biological activated carbon filter (UABACF) treating textile secondary effluent. Modification to the conventional TTC-DHA determination method was proposed. In the modification, BAC samples were used directly to measure TTC-DHA without pre-separating the attached biofilm from carbon samples. After modification, the mean values of biofilm TTC-DHA activities for the BAC samples at different heights of the biofilter were 25 to 193 times higher than those measured in conventional way. In addition, the microbial activity distribution related more closely to substrate removal along the height of the reactor after modification. The results indicated that high activity of the bacteria that are firmly fixed on the porous surface of the media would be ignored during pre-separation of the attached biofilm from media surface. The study also indicated the influence of granular activated carbon (GAC) adsorption on the bio-activity of attached biofilm. GAC adsorption was favorable in the improvement of the activities within the biofilter, especially when the attached films were destroyed. The modification of TTC-DHA determination method made this technique more convenient and accurate in activity measurement of biofilm fixed on porous surface structured activated carbon. Keywords: Up-flow, aerated bio-filter, BAC, TTC-DHA, bioactivity

Study on the Modified triphenyl tetrazolium chloride – dehydrogenase activity (TTC-DHA) Method in Determination of bioactivity in the up-flow aerated bio-activated carbon filter

The study applied triphenyl tetrazolium chloride-dehydrogenase activity (TTC-DHA) method to detect the activities of attached biofilm on bio-activated carbon (BAC) samples in the up-flow aerated biological activated carbon filter (UABACF) treating textile secondary effluent. Modification to the conventional TTC-DHA determination method was proposed. In the modification, BAC samples were used directly to measure TTC-DHA without pre-separating the attached biofilm from carbon samples. After modification, the mean values of biofilm TTC-DHA activities for the BAC samples at different heights of the biofilter were 25 to 193 times higher than those measured in conventional way. In addition, the microbial activity distribution related more closely to substrate removal along the height of the reactor after modification. The results indicated that high activity of the bacteria that are firmly fixed on the porous surface of the media would be ignored during pre-separation of the attached biofilm from media surface. The study also indicated the influence of granular activated carbon (GAC) adsorption on the bio-activity of attached biofilm. GAC adsorption was favorable in the improvement of the activities within the biofilter, especially when the attached films were destroyed. The modification of TTC-DHA determination method made this technique more convenient and accurate in activity measurement of biofilm fixed on porous surface structured activated carbon. Keywords: Up-flow, aerated bio-filter, BAC, TTC-DHA, bioactivity

Enhancement of organic pollutant biodegradation by ultrasound irradiation in a biological activated carbon membrane reactor

The effect of ultrasonics in a biological activated carbon membrane reactor on the removal of organic pollutants in micro-polluted water was investigated through parallel experiments. Results showed that ultrasonics at a power of 10 W could enhance biological activity significantly. The effect of ultrasonic treatment could be maintained for 24 h, so the time interval for ultrasonic treatment should be set at 24 h. The ultrasonic effect on biodegradation was studied through the organic load of the bioreactor, 2,3,5-triphenyl tetrazoliumchloride-dehydrogenase activity (TTC-DHA) of biological activated carbon and the apparent molecular size distribution (AMSD) of the organic compounds in influent and effluent water. The ultrasonic field in the reactor was analyzed and the mechanism of biological activity enhancement by ultrasonics was investigated.

INT–dehydrogenase activity test for assessing anaerobic biodegradability of organic compounds

This study assessed anaerobic biodegradability of organic compounds from microorganism activity. Dehydrogenase activity can be a good parameter characterizing the microorganism activity. A modified method of 2-(p-iodophenyl-3-(p-nitrophenyl)-5-pheny tetrazolium chloride-dehydrogenase activity determination was proposed in anaerobic biodegradability assessment. Cubic spline curves were adopted to link the data points. This curve was integrated twice to calculate areas. The microorganism activity index in anaerobic biodegradability assessment was calculated by standardizing the integral. According to the results of the activity index, 14 kinds of organic compounds were classified into readily, partially, and poorly biodegradable under anaerobic conditions, respectively. As a result, some conclusions for anaerobic biodegradability of organic compounds were reached, based on the activity index value.

Use of calcium peroxide to provide oxygen for contaminant biodegradation in a saturated soil

Laboratory studies were conducted in solid-phase reactors on a silty loam contaminated with bis-(2-ethylhexyl) phthalate (BEHP) to determine the conditions under which calcium peroxide (CaO 2) would promote the aerobic bioremediation of water-saturated soil. Closed 500 ml solid-phase reactors were operated to determine whether CaO 2 stimulated the biodegradation of BEHP in saturated soil. Ex situ bioremediation conditions were then simulated by mixing water-saturated soil for 6 h before placing the soil in three vented, 2 l solid-phase reactors for 50 days. Biodegradation of BEHP was quantified using four different measurements of microbial activity: (1) oxygen concentrations in the reactor gas; (2) bacterial colony-forming units (CFU); (3) fungal CFU; and (4) 2-( p-iodophenyl)-3-( p-nitrophenyl)-5-phenyl tetrazolium chloride dehydrogenase activity (INT-DHA). CaO 2 released molecular O 2, which retarded dewatering but substantially enhanced BEHP biodegradation. After 20 days, BEHP in the amended reactor was reduced from 20.3 to roughly 5 g kg −1 vs. 15 g kg −1 in the reactor without CaO 2. Bacterial growth was favored over fungal growth at elevated moisture and BEHP levels.