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Biofilm enhances the performances of biological wastewater treatment systems. This study aimed to investigate the feasibility of using biodegradable polyhydroxyalkanoate (PHA) pellets as novel biofilm carrier for phenol biodegradation. Two identical laboratory-scale reactors were operated with fill, react, settle, draw and idle periods in the ratio of 2:12:2:1:7 for a 24-h cycle. One reactor was supplemented with 2% (v/v) of PHA pellet and operated as sequencing batch biofilm reactor (SBBR), whereas the other reactor was operated as sequencing batch reactor (SBR) and used as the control reactor. The performances of SBBR and SBR in degrading phenol were studied at three phases with the introduction of 300, 500 and 1000 mg L-1 phenol, respectively. The removal of phenol was found best described using zero-order kinetics, with R2 > 0.97. At all phases, the phenol removal rate during react period for SBBR (7.30 ± 0.55 to 9.33 ± 1.06 mg L-1 min-1) was found higher compared to those for SBR (4.28 ± 0.66 to 8.35 ± 0.68 mg L-1 min-1), with significance difference observed at low phenol concentration. Whereas for chemical oxygen demand biodegradation kinetics, SBRR exhibited significantly higher rate compared to SBR at all phases. From the scanning electron microscopy image, the attachment of activated sludge onto PHA pellet was observed. The results indicated the potential of PHA serving as alternative biofilm carrier in biofilm process.

Five metal-tolerant endophytic isolates (Bipolaris sp. LF7, Diaporthe miriciae LF9, Trichoderma asperellum LF11, Phomopsis asparagi LF15, Saccharicola bicolor LF22), with known metal-tolerance attributes and biocontrol activities against Ganoderma boninense, were tested for growth-promoting activities independent of (in vitro) and associated with plants (height, weight, root mass and stem circumference) (in vivo). Results revealed that metal-tolerant endophytes did not significantly render benefit to host plants as plant growth was compromised by the presence of metals. Lower production of indole-acetic acid (0.74-21.77 μg mL-1), siderophores (8.82-90.26%), and deaminase activities of 1-aminocyclopropane carboxylic acid (3.00-69.2 μmol mg protein-1 hr-1) were observed.

In this study, the bioaccumulation and biosorption of aqueous metals (cadmium, copper, lead, zinc and trivalent chromium) by live and dead cells of Penicillium simplicissimum (isolate 10) were investigated and compared. Removal experiments under varying cell concentrations, pH and initial metal concentrations revealed that live cells generally achieved highest metal removal rates when 0.80 g fresh weight of cells was used, with metal solutions at pH 5 and concentrations of 50–100 mg L−1 (up to 150 and 200 mg L−1 for cadmium and lead, respectively). On the contrary, biosorption of metals by dead cells occurred at maximum rates when as little as 0.15 g dry weight of cells was used, in conditions of pH 5–7 (metal dependent) and lower metal concentration of 50 mg L−1. This comparative analysis suggested that although effective bioremediation by live cells required more cell biomass and preferred the five metals at concentrations of 50–100 mg L−1, the amount of metals removed by live cells were significantly higher (36.2–86.4% for 100 mg L−1 and pH 5) than by dead cells (8.5–58.9%). The results indicated that bioaccumulation is a favourable process that aids in metal removal together with biosorption, and is presumably more effective than the independent process of biosorption alone (by dead cells). Hence, the metal removal potential of P. simplicissimum, especially live cells of this indoor metal-tolerant isolate, may be applied to wastewaters for effective removal within optimum pH range and metal concentrations.

In the absence of various metal ions, live cells of Penicillium simplicissimum decolorized Crystal Violet (CV), Methyl Violet (MV), Malachite Green (MG) and Cotton Blue (CB) (75.6–90.8%, 0.5–2 h) more efficiently than dead cells (43.9–75.2%, 4 h). Cu(II) enhanced CB removal by live and dead cells (64.1–82.0%) but with Cd(II), Zn(II) and Cr(III), removal of CV, MV and MG were inhibited. Pb(II) inhibited dye removal by live cells (63.1–78.1%), while dead cells remained unaffected (40.6–74.0%). Dye removal was attributed to binding to hydroxyl, carbonyl, amino, phosphoryl and nitro groups based on FTIR analyses. Dye-metal-fungi interactions revealed new binding sites and non-involvement of specific functional groups that previously interacted with single dyes. Hence, this study indicated that isolate 10 (especially live cells) is capable of removing dyes from dye-metal solutions.

Two metal-tolerant endophytes (Diaporthe miriciae LF9 and Trichoderma asperellum LF11) were studied in vitro for antifungal activities using dual culture assay. Both isolates inhibited Ganoderma boninense (GB) under metal and non-metal stress, with higher inhibition by T. asperellum LF11 than D. miriciae LF9. T. asperellum LF11 was unaffected by the metals, consistently inhibiting GB (100%) in both conditions. In contrast, inhibitory activities by D. miriciae LF9 was encouraged under metal (32.81–70.64%) compared to non-metal (14.07%) stress; higher in Cu2+ (70.64%) and Zn2+ (63.10%) than Pb2+ (51.79%) and Cd2+ (32.81%). These in vitro activities differed from in vivo findings. After 12 weeks, infected seedlings of oil palms inoculated with D. miriciae LF9 showed lower disease incidence (DI) in non-metal (33%) and multi-metal (67%) treated soils, thus suggesting enhanced tolerance of seedlings towards infection. Treatment with D. miriciae LF9 also delayed the onset of symptoms in the seedlings. Disease severity (DS) was lower for seedlings in non-metal (11%) and multi-metal (22%) treated soils, suggesting D. miriciae LF9 slowed the disease development. On the contrary, T. asperellum LF11 was less effective. Seedlings did not show improved tolerance under non-metal (67%) and multi-metal (100%) stress conditions. The isolate was also less successful in slowing disease development with DS of 33% and 56% observed in seedlings in non-metal and multi-metal treated soils, respectively. The lower endophytic inhibition towards GB in multi-metal treated soils was possibility attributed to higher metal toxicities by the several metals present, thus portraying complex interactions among metals, endophytes and seedlings. Nevertheless, the endophytes suppressed GB in both conditions, hence can be further studied for enhanced performance in metal-laden soils.

A non-white rot fungus, Penicillium simplicissimum (isolate 10), was investigated for its biodegradation activities towards toxic triphenylmethane (TPM) dyes such as Crystal Violet (CV), Methyl Violet (MV), Malachite Green (MG), and Cotton Blue (CB). High decolorization efficiencies of 98.7, 97.5, 97.1, and 96.1% were observed for CV, MV, MG, and CB, respectively, within 2 h of incubation in the dye solutions (50 mg L−1, pH 5.0, 25 ± 2 °C). UV–visible spectral analysis of dyes conducted before and after treatment with P. simplicissimum indicated the occurrence of biodegradation. This was confirmed when enzymatic analyzes revealed induced production of manganese peroxidase (MnP, EC 1.11.1.13; 23.31 U mL−1), tyrosinase (EC 1.14.18.1; 16.18 U mL−1), and triphenylmethane reductase activities (1.15 U mL−1), particularly in biodegrading MG. For MV and CB, increased activities of tyrosinase (20.35 and 18.74 U mL−1, respectively) were detected, whereas no enzyme activities were detected for CV. Dye biodegradation by P. simplicissimum led to reduced toxicity (particularly for MG) based on phytotoxicity and microbial toxicity assays. It was concluded that P. simplicissimum showed potential in biodegrading and detoxifying TPM dyes via MnP, tyrosinase and triphenylmethane reductase activities, resulting in less harmful treated dye solutions.

In this study, sago waste (SW) exhibited great potential in developing an efficient adsorbent in removing methylene blue (MB) from aqueous solution. Three types of adsorbents, namely, powdered SW, carboxymethyl sago pulp (CMSP) hydrogel beads and CMSP-immobilized SW hydrogel beads (CMSP-SW), were produced using SW as the precursor. The MB adsorption was investigated in a batch system to study the effects of experimental parameters of contact time, shaking speed (100–250 rpm), pH (4–10), dosage of SW (0.05–0.30 g) and initial MB concentration (50–250 mg/L). Among the adsorbents, CMSP hydrogel beads showed the lowest adsorption capacity; however, it showed capability in immobilizing SW to prevent the fungal infection and to ease the separation process. The combination of SW and CMSP has resulted in high adsorption capacity of CMSP-SW hydrogel beads for methylene blue, with Langmuir maximum adsorption capacity of 158 mg/g. Equilibrium adsorption data of CMSP-SW were observed to be fitted well into Langmuir isotherm model demonstrating adsorption process was limited to monolayer. On the other hand, the adsorption kinetics of MB onto CMSP-SW was found to be fitted well into pseudo-second order model, suggesting adsorption process was chemisorption. Based on the results obtained from the intraparticle diffusion model, CMSP-SW exhibited two-stage intraparticle diffusion. The reusability test using 50 mg/L of MB showed that the CMSP-SW could be reused up to three cycles with a total of 171 mg/g of MB being removed.

Bioregeneration is a process of restoring the adsorptive capacity of the spent adsorbents through microbial action. In this study, the effects of acclimated biomass concentration, biomass acclimation concentration, dosage of granular activated carbon (GAC) and type of GAC on the bioregeneration efficiency (BE) of GAC loaded with phenol and p-nitrophenol (PNP), respectively, were investigated. The quantification was conducted by monitoring the time courses of adsorbed substrate amount during bioregeneration under the sequential adsorption and biodegradation approach. The mean BEs of phenol- and PNP-loaded GAC were found to be 78 ± 2 and 77 ± 1%, respectively. The results revealed that increasing acclimated biomass concentration and adsorbent dosage did not have an observable effect on the BEs of phenol- and PNP-loaded GAC. Additionally, the BEs were found to be almost the same for the bioregeneration of phenol-loaded GAC using biomass acclimated to 350 and 600 mg/L of phenol, respectively. The BEs of phenol-loaded GAC 830 (thermal-activated) and GAC 1240+ (thermal- and acid-activated) did not show any observable difference, but the BE of PNP-loaded GAC 1240+ was found to be greater than that of PNP-loaded GAC 830 indicating that the improvement of BE of spent GAC through further chemical activation was dependent on the type of adsorbate.

Four fungal isolates: Simplicillium chinense (iso 9, accession no. KX425621), Penicillium simplicissimum (iso 10, KP713758), Trichoderma asperellum (iso 11, KP792512), and Coriolopsis sp. (1c3, KM403574) were subjected to a series of induced-tolerance training under high metal concentrations to determine if greater tolerance could be achieved from constant exposure to such conditions. Adaptive tolerance assay (Tolerance Index, TI) and Field-Emission Scanning Electron Microscopy with Energy Dispersive X-ray (SEM-EDX) characterized their metal tolerance. “Untrained” S. chinense, P. simplicissimum and T. asperellum showed tolerance towards 4000–4500 ppm Al(III) (TI: 0.64–0.71), 1000 ppm Cr(III) (0.52–0.83) and Pb(II) (0.32–0.88). With tolerance training, tolerance towards 2000–6000 ppm Al(III), 500–3000 ppm Pb(II) and 2000–3000 ppm Cr(III) were achieved (TI: 0.01–0.82) compared to untrained cultures (0.00–0.59). In contrast, tolerance training for Coriolopsis sp. and P. simplicissimum was less successful, with TI values similar or lower than untrained cultures. SEM-EDX analysis proposed biosorption and bioaccumulation as mechanisms for metal removal. The latter was demonstrated with the removal of Cr(III) and Pb(II) by S. chinense (12.37 and 11.52 mg g−1, respectively) and T. asperellum (10.44 and 7.50 mg g−1). Induced-tolerance training may render benefit in the long run, but this delicate approach is suggestively species and metal dependent.

This study aims to evaluate the influence of operational factors (i.e. substrate concentration, activated sludge concentration and acclimation concentration) and the microbial communities of activated sludge on the aerobic biodegradation of phenol and p-nitrophenol (PNP). During the biodegradation process, the phenol or PNP biodegradation and activated sludge growth kinetics were determined and the interaction effects of the operational factors on the kinetics were assessed. The phenol biodegradation kinetics was well described by zero-order model (R2 > 0.813). At low phenol concentration (

The insufficiency of mechanistic kinetic model which incorporated the adsorption–coupled reduction mechanism of Cr(VI) was identified and subsequently, reinforced mechanism which better describe the adsorption–reduction of Cr(VI) by sawdust sorbent is proposed. The H+ ion term which was presumably constant in the previous mechanism is currently incorporated into the proposed mechanism, showing the reduction of 2 mol of Cr(VI) require 1 mol of H+ ion. As such, the poorer fit of former kinetic model at increasing initial Cr(VI) concentration and solution pH and decreasing dosage of sawdust was justified. The proposed mechanism is admissible when the H+ concentration is greater than the Cr(VI) concentration at all the arbitrary time of measurement. In the case of reverse condition, the proposed mechanism could no longer describe the Cr(VI) adsorption–reduction process adequately since the surface of sorbent is not fully protonated. The kinetic model derived from the proposed mechanism suggests that the kinetics of Cr(VI) adsorption–reduction is first-order with respect to Cr(VI), organic contents participating in Cr(VI) reduction and H+. Later, the inhibition coefficient derived from the new kinetic model permits the quantification of inhibition effect of various metals acting on the rate of Cr(VI) removal, giving rise to more factual understanding in real application.

This study focuses on the modelling and optimization of process variables for the immobilization of activated sludge in polyvinyl alcohol (PVA)/alginate cryogel beads using response surface methodology (RSM). The results from analysis of variance showed that the models were reliable and significant in predicting the biodegradation rate and beads breakage. The interaction effects of the five independent variables, namely number of freezing-thawing cycle, bead size as well as PVA, alginate and CaCl2 concentrations, were statistically analyzed using central composite design (CCD). Alginate concentration was classified by models for contributing the most significant effect on both responses. The interactions between alginate concentration with CaCl2 concentration, alginate concentration with number of freezing-thawing cycle and alginate concentration with bead size significantly affected the performances of cryogel beads on p-nitrophenol (PNP) biodegradation rate and beads breakage. The predicted results were in conformity with the experimental runs, in which the maximum PNP biodegradation rate of 7.4 mg/L h and minimum breakage of 0 % could be achieved using 8.0 wt % of PVA, 1.411 wt % of sodium alginate, 3.012 wt % of CaCl2, 3.659 mm of bead and 3 cycles for freezing-thawing process. At low initial PNP concentration of 100 mg/L, the PVA/alginate-AS cryogel beads were reusable with no significant loss in PNP biodegradation efficiency for 20 consecutive biodegradation cycles.

A facile and scalable one-pot synthesis method was designed to fabricate N-doped biochar from wood residue for peroxymonosulfate (PMS) activation. The urea:wood residue w/w ratio was varied from 0:1 to 100:1, and the intrinsic (surface chemistry) and extrinsic (morphology, specific surface area, etc.) properties of the N-doped biochar were systematically investigated. Notably, the urea:wood residue w/w ratio played a significant role in tuning the N species composition in the N-doped biochar. A higher urea:wood residue w/w ratio resulted in greater at.% of graphitic N and higher specific surface area. The results show that the catalyst prepared with urea:wood residue w/w ratio of 100:1 (NC800-20) manifested the greatest catalytic activity as PMS activator for organics removal due to its highly favorable combination of intrinsic (highest at.% graphitic N) and extrinsic (excellent specific surface area) properties. The catalyst loading, PMS dosage and pH were found to be operationally crucial for PMS activation. Under the best condition, the NC800-20 can be used to degrade various organic pollutants. The recyclability of NC800-20 was studied and while the catalytic activity gradually deteriorated over successive cycles, it can be completely restored by simple calcination at 500 °C. The used catalyst was extensively characterized, revealing insights into the mechanism of PMS activation. The prevailing mechanism for PMS activation was the nonradical pathway. Overall, this research provides insights into preparing N-doped biochar with favorable extrinsic and intrinsic properties from biowaste for sustainable pollutant removal via PMS activation.

The metal removal efficiency of live and dead fungal cells of Penicillium simplicissimum (isolate 10, KP713758) was tested against 100 ppm toxic metals Cd, Cu, Pb, Zn and trivalent Cr in single-metal solutions and in mixtures with 50 ppm triphenylmethane (TPM) dyes (Cotton Blue, Crystal Violet, Methyl Violet, and Malachite Green). Results revealed that live cells were more effective at removing metals from single (10.8–70.0%) and dye-metal mixtures (5.3–62.2%) than dead cells (5.1–27.4%). The dyes in dye-metal mixtures influenced metal uptake capacity. All four dyes inhibited the uptake of Cd (0.9–7.1%), Zn (5.3–7.7%), Cu (5.0–25.8%) and Cr (47.3–60.7%) by live cells. The exception was the enhance removal of Pb by live cells (48.6 to 56.3–62.2%) in the presence of dye (MG or CB). Pb uptake was not affected by MV (51.8%), but was inhibited by CV (31.9%). For dead cells, uptake of metals (Cd, Cr and Zn) in single (3.2–27.4%) and dye-metal solutions (0.7–27.4%) was similar, whilst removal of Cu (6.4–13.5%) and Pb (33.6–44.0%) was inhibited by all four dyes. P. simplicissimum is concluded to have potential to remove toxic metals even in the presence of TPM dyes, with preferred use of live cells than dead cells.

Penicillium simplicissimum (isolate 10), a metal tolerant fungus, tolerated 1000 mg/L Cu and 500 mg/L Zn, but were inhibited by Cd (100 mg/L), evident by the Tolerance Index (TI) of 0.88, 0.83, and 0.08, respectively. Live cells of P. simplicissimum were more effective in removing Cr (88.6%), Pb (73.7%), Cu (63.8%), Cd (33.1%), and Zn (28.3%) than dead cells (5.3–61.7%). Microscopy approach via SEM-EDX and TEM-EDX suggested that metal removal involved biosorption and bioaccumulation, with metal precipitates detected on the cell wall, and in the cytoplasm and vacuoles. FTIR analysis revealed metals interacted with amino, carbonyl, hydroxyl, phosphoryl (except Cd) and nitro groups in the cell wall. Biosorption and bioaccumulation of metals by live cells reduced Cu and Pb toxicity, observed from good root and (4.00–4.28 cm) and shoot (8.07–8.36 cm) growth of Vigna radiata in the phytotoxicity assay.

Studies on the development of alternative adsorbent using rice husk have been extensively reported. However, relatively little has been reported on the comparative adsorptive removal of phenolic compounds using rice husk activated with different methods as well as their bioregeneration potential and reusability. This study aimed to investigate the adsorption capacities of rice husk activated with nitric acid (ARH), ethylenediamine (MRH), and potassium hydroxide (KRH), respectively, for 4-chlorophenol (4-CP) and 2,4-chlorophenol (2,4-DCP) in comparison to powdered activated carbon (PAC) and the bioregeneration efficiencies and reusability of chlorophenol-loaded activated rice husks. For both cases using 4-CP and 2,4-DCP as adsorbates, the adsorption capacities were found in the order of KRH > PAC > ARH > MRH. Despite the much lower abiotic desorption efficiencies, the bioregeneration efficiencies were found comparable for all the adsorbents (>80% for the first cycle except for 2,4-DCP-loaded KRH). ...

Fifteen endophytic isolates were recovered from the phytoremediator plant Phragmites. Phylogenetic analysis revealed they were primarily from the class Sordariomycetes and Dothiodiomycetes. Most of the endophytes in Sordariomycetes were from the orders Diaporthales (six isolates, e.g., Diaporthe, Phomopsis), Hypocreales (two isolates, e.g., Gliomastix, Trichoderma), and Xylariales (one isolate, e.g., Arthrinium), while members from Dothideomycetes were from the order Pleosporales (six isolates, e.g., Bipolaris, Curvularia, Microsphaeropsis, Saccharicola). The endophytes demonstrated varying responses to the metals (Al3+, Cu2+, Zn2+, Pb2+, and Cd2+) and concentrations (10, 25, 50, 100, and 200 mg L−1) tested, with isolates of Dothideomycetes predominantly more tolerable to metals (80–97% tolerance) than Sordariomycetes (73–90% tolerance). Pb2+ was the least harmful towards the endophytes, while Al3+ appeared to be highly toxic with mean tolerable range (TR) of > 200 and 25–50 mg L−1, respectively. Endophytes thriving in toxic metals may further be applied for biocontrol, bioremediation, or growth-promoting purposes in metal-contaminated areas.

In this study, Fe 3+ was embedded in graphitic carbon nitride (g-C 3 N 4 ) and used as a catalyst for acid orange 7 (AO7) removal via peroxymonosulfate (PMS) activation. The w/w% Fe 3+ dopant was varied (0 – 2.5) and the changes in the physical and chemical characteristics of g-C 3 N 4 after Fe 3+ doping were studied. The results indicated that, while there was no distinct change in the g-C 3 N 4 morphology, Fe 3+ doping increases the specific surface area and catalytic active sites for enhanced PMS activation. However, increasing the Fe 3+ doping decreased the structural stability of the g-C 3 N 4 . It was found that the g-C 3 N 4 with 2.5 w/w% Fe 3+ dopant (denoted as gCN-Fe3) gave the highest AO7 removal rate (initial rate constant, k i = 0.096 min -1 ) with at least 5.6 higher than that of g-C 3 N 4 . The effects of PMS dosage, gCN-Fe3 loading and pH on AO7 removal were investigated. The results showed that increasing the gCN-Fe3 loading provided ∼3.7 times better performance enhancement compared to increasing the PMS dosage while pH 5 ( k i = 0.151 min -1 ) was the optimum pH. The chemical scavengers were employed to identify the dominant reactive species. Based on the results, it is proposed that higher valent Fe species generated from the interaction between PMS and Fe 3+ is the dominant reactive species. The results also indicated that gCN-Fe3 can still retain its catalytic activity after three cycles and AO7 mineralization was achieved. Besides AO7, the gCN-Fe3/PMS system can be employed to degrade various other organics including antibiotics and endocrine disruptors. This indicates that the catalyst has promising application as PMS activator for organics removal.

The feasibility of using polyvinyl alcohol (PVA) hydrogel beads encapsulating powdered activated carbon (PAC) and biomass for the enhancement of o-cresol removal via simultaneous adsorption and biodegradation was investigated in this study. The optimum concentrations of PVA and PAC used to synthesize spherical PVA hydrogel beads with 3–4 mm diameter were found to be 7.5 and 0.5% (w/v), respectively. The results of kinetic studies showed that the rate constant of o-cresol removal for the initial o-cresol concentration range of 100–400 mg/L could be sustained when the immobilized biomass supplemented with PAC in hydrogel beads was used. However, the removal of o-cresol was inhibited for the initial o-cresol concentration above 150 mg/L when only immobilized biomass in the beads was used. Thus, the supplementation of PAC to the immobilized biomass in the beads could enhance the removal of o-cresol via simultaneous adsorption and biodegradation.

The effects of dry biomass density in cryogel beads, shaking speed and initial concentration ratio of phenol to 4-chlorophenol (4-CP) on the bioregeneration efficiencies of binary phenol and 4-CP-loaded granular activated carbon (GAC) for phenol and 4-CP, respectively, were investigated under the simultaneous adsorption and biodegradation approach. The results revealed higher bioregeneration efficiencies of binary-loaded GAC for phenol and 4-CP at higher dry biomass density but moderate shaking speed. The optimum dry biomass density in cryogel beads and shaking speed for use in bioregeneration were found to be 0.01 g/mL and 250 rpm, respectively. With respect to the initial phenol to 4-CP concentration ratio, the bioregeneration efficiencies were lower under increasing phenol and 4-CP initial concentrations, respectively, with the effect being more conspicuous under increasing 4-CP concentration. Higher bioregeneration efficiencies were achieved with the use of immobilized rather than suspended biomasses.

The potential of crosslinked carboxymethyl sago pulp (CMSP) beads immobilized with powdered activated carbon (PAC) as an adsorbent for methylene blue (MB) adsorption was investigated. The finely powdered PAC had an excellent adsorption capacity for MB but was disadvantageous for the separation process from treated effluents. To ease the separation process, the CMSP medium could be advantageous for the process by acting an immobilizing medium for PAC. The MB adsorption reached equilibrium at the 14th hour, and further adsorption was studied to determine the effects of the CMSP concentration, PAC dosage, and pH. Different CMSP concentrations in the preparation of CMSP–PAC beads showed no significant differences; this proved that CMSP–PAC adsorbed more MB than CMSP did. The MB adsorption increased with increasing PAC concentration, whereas the CMSP–PAC beads disintegrated at pH 11.5. In the equilibrium study, the Langmuir isotherm fit well into the experimental data with a linear correlation coefficient (R2) of 0.9837 and a maximum adsorption capacity of 250 mg/g. The kinetic study showed that pseudo-second-order kinetics accommodated the experimental data well with an R2 value of 0.9512 and a pseudo-second-order rate constant value of 3.61 × 10−3 min−1. The crosslinked CMSP–PAC beads have the potential to remove MB dye, and this could be exploited as an alternative to treating colored dye effluents produced by industries such as the textile, printing, and cosmetics industries. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44271.

We examined the inhibitory effect of 2,4-dichlorophenol (2,4-DCP) on nitrogen removal in the sequencing batch reactor (SBR) system. The reactor was operated with FILL, REACT (nitrification: denitrification), SETTLE, DRAW and IDLE phases in the duration ratio of 2: 12 (9: 3): 1: 1: 8 for a 24 h cycle time. The deterioration of 2,4-DCP removal efficiency from 100 to 41% was observed when the influent concentration of 2,4-DCP was increased to 30mg/L. The residual 2,4-DCP remaining in the mixed liquor was found to inhibit the nitrification process, resulting in the decrease of nitrogen removal efficiency to 25 %. For kinetic study, the result showed that the experimental data of ammoniacal nitrogen (AN) removal at every stage fitted well to the first-order kinetics equation with high R2 values. The rate constant of AN removal, k AN , decreased with increasing influent concentration of 2,4-DCP, from 0.053 to 0.0006/min when 2,4-DCP concentration increased from 0 to 30 mg/L, respectively. However, the observed gradual recovering of AN removal with respect to the removal efficiency and kinetics during the recovery stage indicated that the inhibitory effect of 2,4-DCP on the nitrification process was reversible.

The performance of moving bed sequencing batch reactors (MBSBRs) added with 8 % (v/v) of polyurethane (PU) foam cubes as carrier media in nitrogen removal was investigated in treating low COD/N wastewater. The results indicate that MBSBR with 8-mL cubes achieved the highest total nitrogen (TN) removal efficiency of 37% during the aeration period, followed by 31%, 24% and 19 % for MBSBRs with 27-, 64- and 125-mL cubes, respectively. The increased TN removal in MBSBRs was mainly due to simultaneous nitrification and denitrification (SND) process which was verified by batch studies. The relatively lower TN removal in MBSBR with larger PU foam cubes was attributed to the observation that larger PU foam cubes were not fully attached by biomass. Higher concentrations of 8-mL PU foam cubes in batch reactors yielded higher TN removal.

A kinetic model consisting of first-order desorption and biodegradation processes was developed to describe the bioregeneration of phenol- and p-nitrophenol-loaded powdered activated carbon (PAC) and pyrolyzed rice husk (PRH), respectively. Different dosages of PAC and PRH were loaded with phenol or p-nitrophenol by contacting with the respective phenolic compound at various concentrations. The kinetic model was used to fit the phenol or p-nitrophenol concentration data in the bulk solution during the bioregeneration process to determine the rate constants of desorption, k(d), and biodegradation, k. The results showed that the kinetic model fitted relatively well (R(2)>0.9) to the experimental data for the phenol- and p-nitrophenol-loaded PAC as well as p-nitrophenol-loaded PRH. Comparison of the values of k(d) and k shows that k is much greater than k(d). This indicates clearly that the desorption process is the rate-determining step in bioregeneration and k(d) can be used to characterize the rate of bioregeneration. The trend of the variation of the k(d) values with the dosages of PAC or PRH used suggests that higher rate of bioregeneration can be achieved under non-excess adsorbent dosage condition.

(ii) investigate the degradation pathways and (iii) model the growth and biodegradation kinetics, all under the condition of increasingly higher phenol concentrations (step-up shock loading). With the use of activated sludge acclimated to phenol concentration of 140 mg∙l−1 (low-strength phenol-acclimated activated sludge), complete degradation of phenol with a COD removal efficiency of more than 95% was achieved up to 1 050 mg∙l −1 of initial phenol concentration. At low initial phenol concentrations, the experimental results were indicative of the meta-cleavage pathway for phenol degradation. When the initial phenol concentration was above 630 mg∙l −1 , the degradation results were indicative of both meta- and ortho-cleavage pathways. The values of the Haldane kinetic parameters indicated a low degree of inhibition exerted by the presence of increasing phenol concentration. This was substantiated by the observation that the rate constant of phenol removal decreased by only 33% even though the initial phenol concentration was increased by 15 times from 70 to 1 050 mg∙l −1 . Thus, the activated sludge acclimated to only 140 mg∙l −1 of phenol could successfully treat up to 1 050 mg∙l −1 of phenol without experiencing complete inhibition during the degradation process. Keywords: Phenol removal, low-strength phenol-acclimated activated sludge, degradation pathway, Haldane kinetic parameter

The objective of this study was to evaluate the effects ofNi(II) and Cr(VI) individually and in combination on the simultaneous removal of chemical oxygen demand (COD), nitrogen and metals under a sequencing batch reactor (SBR) operation. Three identical laboratory-scale SBRs were operated with FILL, REACT, SETTLE, DRAW and IDLE periods in a ratio of 1:12:1:2:8 for a cycle time of 24 h until the steady state was achieved. Nickel(II) at increasing concentrations up to 35 mg/L was added to one of the reactors; Cr(VI) at increasing concentrations up to 25 mg/L was added to a second reactor; while a combination of Ni(II) and Cr(VI) in equal concentrations up to 10 mg/L was added to a third reactor. The results demonstrate that both Ni(II) and Cr(VI) exerted a more pronounced inhibitory effect on the removal of ammonia nitrogen (AN) than on COD removal. Synergistic and antagonistic inhibitory effects on the rates of COD and AN removal, respectively, were observed for the 50% Ni(II) and 50% Cr(VI) (w/w) mixture in the concentration range between 10 and 20 mg/L. The simultaneous presence of 50% Ni(II) and 50% Cr(VI) at a concentration of 20 mg/L resulted in system failure.

In this study, the removal of Cu(II) from aqueous solutions using living and non-living cultured sludges of different sludge ages was investigated. For non-living sludge, only the metabolism-independent bio-adsorption process occurred and Langmuir model was adequate to describe the adsorption isotherm. When living sludge was used as the adsorbent, a proposed model incorporating the bio-adsorption and bioaccumulation processes in sequence was found to fit better than the Langmuir model and provided a better interpretation of the metal uptake by living sludge. The bioaccumulation process was observed to be the predominant process in removing Cu(II) from the aqueous solutions.