•Seasonal plant collocation wetland system performed well at low temperature.•Plant growth and plant uptake were sustainable during the year-round experiment.•DO and ammonia oxidizing bacteria were ...enriched benefitting from plant collocation.
In the present study, a novel seasonal plant collocation system (SPCS), specifically the Potamogeton crispus and Phragmites australis series system, was investigated to enhance the performance of surface flow constructed wetlands (SFCWs) at low temperature. Results of a year-round experiment showed that SPCS conquered the adverse effect of low temperature and achieved sustainable nutrients removal. In addition, during winter, removal efficiencies of NH4-N, TP, COD, and TN in SPCS were 18.1%, 17.6%, 10.1% and 5.2% higher than that in the control, respectively. P. crispus and P. australis complemented each other in terms of plant growth and plant uptake during the experiment period. Furthermore, it emerged that P. crispus could increase the quantity of ammonia oxidizing bacteria by 10.2%, due to its high oxygen enrichment ability. It is suggested that seasonal plant collocation has a promising future in SFCWs of areas being affected by climate change, e.g. northern China.
Water pollution caused by Cu2+ ions poses a significant threat to the ecosystem and human health, hence the development of highly cost-effective, highly operation-convenient and highly efficient ...natural polymer-based adsorbents is urgently needed. To overcome this serious problem, a novel cost-effective magnetic chitosan composite adsorbent (CsFeAC) was prepared with magnetic macroparticles and highly porous activated carbon carrier using the sol-gel method. Several methods, namely SEM, BET, FTIR, XRD, TGA and VSM, were applied to characterize the adsorbent. Batch tests were conducted to investigate Cu2+ adsorption properties of CsFeAC at different pH values, contact time, initial Cu2+ concentrations and temperatures. The adsorption fits better to the Langmuir isotherm and follows the pseudo-second-order model, suggesting that it is a monolayer adsorption and the rate-limiting step is the chemical chelating reaction. The saturated adsorption capacity is found to be 216.6 mg/g. Thermodynamics analysis suggests that the adsorption process is endothermic, with increasing entropy and spontaneous in nature. BET and XRD tests confirm that the higher specific surface area and lower crystallinity of CsFeAC significantly improve the absorption capacity and rate. FTIR spectra reveal that the amino and hydroxyl groups play an important role in the chelating adsorption. The supermagnetic property of CsFeAC facilitates its easy separation characteristic. Further recycling experiments show that CsFeAC still retains 95% of the original adsorption following the 5th adsorption-desorption cycle. All these results demonstrate that CsFeAC is a promising recyclable adsorbent for removing Cu2+.
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•A novel magnetic chitosan composite adsorbent was prepared by the sol-gel method.•The adsorbent was characterized by SEM, BET, FTIR, XRD, TGA and VSM methods.•The adsorption fits well with the Langmuir isotherm and pseudo-second-order model.•The adsorbent exhibited high adsorption capacity for the Cu2+ irons.•Easy separation and good reusability make the adsorbent attractive for further practical application.
Application of biochars to remove inorganic nitrogen (NH4+, NO2−, NH3, NO, NO2, N2O) from wastewater and agricultural fields has gained a significant interest. This study aims to investigate the ...relationship between ammonium sorption and physicochemical properties of biochars derived from different kinds of fruit peel. Biochars from three species of fruit peel (orange, pineapple and pitaya) were prepared at 300, 400, 500 and 600 °C with the residence time of 2 h and 4 h. Their characteristics and sorption for ammonium was evaluated. The results show a clear effect of pyrolysis conditions on physicochemical properties of biochars, including elemental composition, functional groups and pH. The maximum NH4+ adsorption capacities were associated with biochars of orange peel (4.71 mg/g) and pineapple peel (5.60 mg/g) produced at 300 °C for 2 h. The maximum NH4+ adsorption capacity of the pitaya peel biochar produced at 400 °C for 2 h was 2.65 mg/g. For all feedstocks, biochars produced at low temperatures showed better NH4+ adsorption capacity. It was found that biochars had better adsorption efficiency on ammonium at a pH of 9. Adsorption kinetics of ammonium on biochars followed the pseudo-second-order kinetic model while Langmuir isotherm model could well simulate the adsorption behavior of ammonium on biochars. The adsorption mechanism of ammonium on biochars predominantly involved surface complexation, cation exchange and electrostatic attraction. Conclusively, the fruit peel-derived biochars can be used as an alternative to conventional sorbents in water treatment.
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•Biochars from three kinds of fruit peel were prepared.•Biochar derived from pineapple peel had a higher sorption capacity for NH4+.•Elemental and functional groups play a critical role in adsorption of NH4+.•Biochar has better adsorption capacity for ammonium at low temperature.•Chemical adsorption is the dominant mechanism of NH4+ adsorption.
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•High oxygen supply efficiency is observed in SFCWs with P. crispus in cold winter.•High average removal rates of COD (92.45%) and NH4+-N (93.70%) were obtained.•The underground part ...of P. australis enhanced wetlands performance in winter.
In this study, enhanced organics and nitrogen removal efficiency in SFCWs by different submerged plants for polluted river water treatment under cold temperature was evaluated. High average removal efficiencies of COD (92.45%), NH4+-N (93.70%) and TN (55.62%) were achieved in experimental SFCWs with Potamogeton crispus compared with SFCWs with other plants. SFCWs with underground Phragmites australis root also presented better performance than the unplanted systems, indicating its positive role of contamination removal in winter. The results of this study indicated SFCWs with hardy submerged plant P. crispus could be a more effective and sustainable strategy for removing organics and nitrogen in shallow nutrient enriched river water ecosystems under cold climate.
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•Seven types of food wastes were selected and collected for making biochars.•Optimal pyrolysis temperature for preparing biochars is 300 °C.•The biochar made from fruit pericarps was ...best in removing ammonia nitrogen.•Highest ammonia removal efficiency was achieved at a dosage of 3 g/L at 25 °C.•Starchy staples, meat and bone based biochars had lower ammonia removal efficiency.
Biochar derived from waste has been increasingly considered as a potential green adsorbent due to its significant ability and affordable production costs. This study prepared and evaluated 7 types of food waste-based biochars (FWBBs) (including meat and bone, starchy staples, leafy stemmed vegetables, nut husks, fruit pericarp, bean dreg and tea leaves). The impacts of raw materials, pyrolysis temperatures (300, 400, 500, 600 and 700 °C), and residence time (2 h and 4 h) on the removal of ammonia nitrogen at different ammonia nitrogen concentrations (5, 10, 20, 50, 100, 150 mg/L) were investigated. The batch equilibrium and kinetic experiments confirmed that a FWBB dosage of 3 g/L at 25 °C could remove up to 92.67% ammonia nitrogen. The Langmuir isotherm model had the best fit to equilibrium experimental data with a maximum adsorption capacity of 7.174 mg/g at 25 °C. The pseudo-second order kinetic model well describes the ammonia nitrogen adsorption.
The current methods used for the production of activated carbon (AC) are often chemical and energy intensive and produce significant amount of chemical waste. Thus, clean production of AC is ...important to reduce its overall production cost and to limit the adverse effect on the environment. Therefore, the main aim of this study is to develop a clean method for AC production from woody biomass with low chemical consumption. Herein, this study reports a facile strategy for reducing chemical usages in the production of high-performance AC, by introducing a crucial pre-pyrolysis step before chemical activation of biomass. The ACs prepared were characterised using scanning electron microscopy, Fourier transform infrared spectroscopy, nitrogen and carbon dioxide gas adsorption measurements. All these characterisations indicated that produced ACs have similar physicochemical properties. The strategy reduced chemical use by 70% and produced high-performance ultra-microporous ACs with excellent carbon dioxide adsorption capacity (4.22–5.44 mmol m−2). The facile pre-pyrolysis method is recommended for further research as a cleaner activated carbon preparation method from biomass feedstock.
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•Pre-pyrolysis reduced chemical consumption by 70.00% for AC production.•Pre-pyrolysis produced high-performance ultra-micropore AC.•Excellent CO2 capture performance for ZnCl2 activated AC.•All AC showing similar physicochemical properties.
•Partial nitrification granular sludge was successfully cultivated in a SBR.•The effluent NH4+-N/NO2−-N ratio was about 1:1 with NAR at 87.8%.•MLSS and SVI30 of SBR were 14.6 g/L and 25.0 mL/g, ...respectively.•Nitrosomonas affiliated to the AOB was the predominant group.
Partial nitrification granular sludge was successfully cultivated in a sequencing batch reactor as a pretreatment for anaerobic ammonium oxidation (Anammox) through shortening settling time. After 250-days operation, the effluent NH4+-N and NO2−-N concentrations were average at 277.5 and 280.5 mg/L with nitrite accumulation rate of 87.8%, making it as an ideal influent for Anammox. Simultaneous free ammonia (FA) and free nitrous acid (FNA) played major inhibitory roles on the activity of nitrite oxidizing bacteria (NOB). The MLSS and SVI30 of partial nitrification reactor were 14.6 g/L and 25.0 mL/g, respectively. Polysaccharide (PS) and protein (PN) amounts in extracellular polymeric substances (EPS) from granular sludge were about 1.3 and 2.8 times higher than from seed sludge. High-throughput pyrosequencing results indicated that Nitrosomonas affiliated to the ammonia oxidizing bacteria (AOB) was the predominant group with a proportion of 24.1% in the partial nitrification system.
Recently, the application of the microbial fuel cell (MFC)-based biosensor for rapid and real-time monitoring wastewater quality is very innovative due to its simple compact design, disposability, ...and cost-effectiveness. This review represents recent advances in this emerging technology for the management of wastewater quality, where the emphasis is on biochemical oxygen demand, toxicity, and other environmental applications. In addition, the main challenges of this technology are discussed, followed by proposing possible solutions to those challenges based on the existing knowledge of detection principles and signal processing. Potential future research of MFC-based biosensor has been demonstrated in this review.
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•MFCs-based biosensor is an innovative technology for wastewater quality detection.•No transducer is needed for MFC-based biosensors to read and convert the signal.•MFCs sensor's limitations are sensitivity, irreproducibility, labor scaling and stability.•Future research on improving electrodes' material and configurations is essential.
Concentration of eight heavy metals in surface and groundwater around Dhaka Export Processing Zone (DEPZ) industrial area were investigated, and the health risk posed to local children and adult ...residents via ingestion and dermal contact was evaluated using deterministic and probabilistic approaches. Metal concentrations (except Cu, Mn, Ni, and Zn) in Bangshi River water were above the drinking water quality guidelines, while in groundwater were less than the recommended limits. Concentration of metals in surface water decreased as a function of distance. Estimations of non-carcinogenic health risk for surface water revealed that mean hazard index (HI) values of As, Cr, Cu, and Pb for combined pathways (i.e., ingestion and dermal contact) were >1.0 for both age groups. The estimated risk mainly came from the ingestion pathway. However, the HI values for all the examined metals in groundwater were <1.0, indicating no possible human health hazard. Deterministically estimated total cancer risk (TCR) via Bangshi River water exceeded the acceptable limit of 1 × 10−4 for adult and children. Although, probabilistically estimated 95th percentile values of TCR exceeded the benchmark, mean TCR values were less than 1 × 10−4. Simulated results showed that 20.13% and 5.43% values of TCR for surface water were >1 × 10−4 for adult and children, respectively. Deterministic and probabilistic estimations of cancer risk through exposure to groundwater were well below the safety limit. Overall, the population exposed to Bangshi River water remained at carcinogenic and non-carcinogenic health threat and the risk was higher for adults. Sensitivity analysis identified exposure duration (ED) and ingestion rate (IR) of water as the most relevant variables affecting the probabilistic risk estimation model outcome.
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•Deterministic and probabilistic approaches were used to determine health risk.•Water Ingestion pathway contributed the most to estimated risk.•People exposed to river water were at risk.•No health hazard was observed for groundwater drinking.•ED and IR of water were the major contributors to probabilistic risk calculation.
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