Phosphate Removal Efficiency Research Articles

Spatiotemporal succession of phosphorous accumulating biofilms during the first year of establishment.

Many wastewater treatment plants are dependent on the utilization of microorganisms in biofilms. Our knowledge about the establishment of these biofilms is limited, particular with respect to biofilms involved in enhanced biological phosphorus removal (EBPR). These biofilms rely on polyphosphate-accumulating organisms (PAOs), requiring alternating oxic and anaerobic conditions for phosphorous uptake. This challenge has been solved using the Hias process, which combines moving-bed biofilm-reactor (MBBR) technology with physical transfer of biofilm-carriers from oxic to anaerobic zones. We combined biofilm fractionation with temporal analyses to unveil the establishment in the Hias process. A stable phosphorous removal efficiency of >95% was reached within 16 weeks of operation. Phosphorus removal, however, was not correlated with the establishment of known PAOs. The biofilms seemed associated with an outer microbiota layer with rapid turnover and an inner layer with a slow expansion. The inner layer showed an overrepresentation of known PAOs. In conclusion, our spatiotemporal analyses of phosphorous accumulating biofilm establishment lead to a new model for biofilm growth, while the mechanisms for phosphorous removal remain largely unresolved.

Microalgae Cultivation Using Municipal Wastewater and Anaerobic Membrane Effluent: Lipid Production and Nutrient Removal

Microalgae cultivation using wastewater is a combined process for pollutant removal and lipid production that has been widely studied in recent years. In this study, the effects of anaerobic membrane effluent (AME) and municipal wastewater (MW) ratios on microalgae growth and pollutant removal processes were investigated, and the lipid production properties were also explored. Results show that microalgae can grow in all AME/WW ratios, and a 40% AME content is the optimal condition for microalgal biomass accumulation (52.9 mg/L·d) and lipid production (0.378 g/L). Higher AME addition would inhibit microalgae growth. In addition, high ammonia (approximately 97%) and phosphate (around 90%) removal efficiencies can be achieved in all AME/WW ratio conditions, while the total nitrogen removal efficiencies decreased with the addition of AME. Total nitrogen and phosphate are the limiting factors in treating water to meet the requirements of the integrated wastewater discharge standard. This study provided a new method for anaerobic digestion and municipal wastewater treatment and also realized green energy production based on the sustainable development principles.

Investigation on surface water treatment using blended moringa oleifera seed and aloe vera plants as natural coagulants

The implementation and careful adaptation of treatment plants is currently the most common method for enhancing water quality, especially for large-scale supplies. Nowadays, natural coagulants are used for water treatment due to their environmental friendliness. moringa oleifera and Aloe vera plants are the known natural coagulants used for water. The main goal of this study was to evaluate the removal efficiency of color, turbidity, TDS, COD, and phosphate from surface water by utilizing the blended powder of moringa oleifera seeds (MOS) and Aloe vera plants (AVP). In this study also, pH, stirring speed of the jar test, coagulant dosage, and settling time were also considered as influencing factors on the removal percentages. The blended powder of moringa oleifera (MOS) and Aloe vera plants (AVP) removed color (87.1%), turbidity (88.5%), TDS (92.1%), COD (52.6%), and phosphate (93.9%) at different operating parameters at optimum condition. Furthermore, experimental data were statistically and mathematically analyzed using a central composite design (CCD) from response surface methodology (RSM), revealing that the quadratic model was significant for COD and phosphate removal. The model was also valid for the COD and phosphate removal based on the coefficient of determination, but the quadratic model for the removal of color, turbidity, TDS, and COD was aliased such that it is not appropriate for further investigation.

Treatment of Dairy Wastewater by Electrocoagulation using Iron Filings Electrodes

This study investigated the treatment of dairy wastewater using the electrocoagulation method with iron filings as electrodes. The study dealt with real samples collected from local factory for dairy products in Baghdad. The Response Surface Methodology (RSM) was used to optimize five experimental variables at six levels for each variable, for estimating chemical oxygen demand (COD) removal efficiency. These variables were the distance between electrodes, detention time, dosage of NaCl as electrolyte, initial COD concentration, and current density. RSM was investigated the direct and complex interaction effects between parameters to estimate the optimum values. The respective optimum value was 1 cm for the distance between electrodes, (60 – 120) min for detention time, 250 mg NaCl/L added, C0/6 = 5,775 mg COD/L as initial COD concentration, and 7.884 - 8.077 mA/cm2 as current provided. At the optimum parameter values, the optimum COD removal efficiency was 73.4%. Meanwhile, the study also performed removal efficiency for nitrogen (N) and phosphate (P) due to their effects on the aquatic life and systems. The optimum removal efficiency for phosphorus and nitrogen was 98.0% and 80.3%, respectively. Due to its effects on the environment and to comply with local legislations, treating these wastewaters using eco-friendly processes was highly recommended taking in consideration the economic feasibility, flexibility and easiness to operate. In addition, the study proved that the high surface area for iron filings played a crucial role in removing process.

Preparation and Adsorption Behavior of Ce(III)-MOF for Phosphate and Fluoride Ion Removal from Aqueous Solutions.

The discharge of inorganic pollutants like phosphate and fluoride is a cause of mounting concern to the world due to the substantial environmental and human health risk. Adsorption is one of the most common and affordable technologies widely utilized for removing inorganic pollutants such as phosphate and fluoride anions. Investigating efficient sorbents for the adsorption of these pollutants is extremely important and challenging. This work aimed at studying the adsorption efficiency of the Ce(III)-BDC metal-organic framework (MOF) for the removal of these anions from an aqueous solution using a batch mode. Powder X-ray diffraction (XRD), Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), Brunauer-Emmett-Teller (BET), and scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX) techniques evidenced the successful synthesis of Ce(III)-BDC MOF in water as a solvent without any energy input within a short reaction time. The outstanding removal efficiency of phosphate and fluoride was exhibited at an optimized pH (3, 4), adsorbent dose (0.20, 0.35 g), contact time (3, 6 h), agitation speed (120, 100 rpm), and concentration (10, 15 ppm) for each ion, respectively. The experiment on the effect of coexisting ions demonstrated that SO42- and PO43- ions are the primary interfering ions in phosphate and fluoride adsorption, respectively, while the HCO3- and Cl- ions were found to have interfered less. Furthermore, the isotherm experiment showed that the equilibrium data fitted well with the Langmuir isotherm model and the kinetic data correlated well with the pseudo-second-order model for both ions. The results of thermodynamic parameters such as ΔH°, ΔG°, and ΔS° evidenced an endothermic and spontaneous process. The regeneration of the adsorbent made using water and NaOH solution showed the easy regeneration of the sorbent Ce(III)-BDC MOF, which can be reused four times, revealing its potential application for the removal of these anions from aqueous environment.

Adsorption of phosphate in water by La/Al bimetallic-organic frameworks-chitosan composite with wide adaptable pH range

The limited metal sites of monometallic MOFs and the high influence of pH limit their adsorption capacity. To solve these problems, La/Al bimetallic MOFs/chitosan composite was prepared by hydrothermal synthesis and impregnation methods and then characterized by XRD, FTIR, SEM, BET and XPS techniques. The doping of La has no obvious effect on the structure of Al-MOFs, but chitosan has greatly changed the structure of La/Al bimetallic MOFs. The phosphate adsorption of the composite was affected by La/Al molar ratio, chitosan/bimetallic MOFs mass ratio, temperature, phosphate initial concentration, adsorbent dosage, pH, and coexisting ions. The optimum molar ratio of La/Al and mass ratio of chitosan/bimetallic MOFs are 0.5:1 and 5.0%, respectively. The addition of La and chitosan can provide additional adsorption active sites, inhibit metal leaching, and enhance the phosphate adsorption performance, stability, and acid-alkali resistance of the composite. Its maximum adsorption capacity was 264.48 mg·g−1. Its phosphate removal efficiency is above 90% at pH= 3.0–9.0. The actual phosphorus-containing wastewater with 7.064 mg·L−1 PO43- and initial pH 7.4 can be treated to meet Chinese first-class effluent quality standard. La, Al, amino groups, and hydroxyl groups play an important role in the adsorption process of phosphate. When pH < pHpzc (4.99), phosphate is adsorbed by electrostatic gravitation between it and protonated positively charged amino and hydroxyl groups on La and Al, while when pH > pHpzc, phosphate is removed by ligand exchange between it and hydroxyl groups on La and Al. A stable, low-cost, and efficient bimetallic MOFs-based phosphate adsorbent was designed and prepared in this paper, and the results can provide reference for researchers in environmental chemical engineering.

Zirconium Component Modified Porous Nanowood for Efficient Removal of Phosphate from Aqueous Solutions.

Rapid urban industrialization and agricultural production have led to the discharge of excessive phosphate into aquatic systems, resulting in a rise in water pollution. Therefore, there is an urgent need to explore efficient phosphate removal technologies. Herein, a novel phosphate capture nanocomposite (PEI-PW@Zr) with mild preparation conditions, environmental friendliness, recyclability, and high efficiency has been developed by modifying aminated nanowood with a zirconium (Zr) component. The Zr component imparts the ability to capture phosphate to the PEI-PW@Zr, while the porous structure provides a mass transfer channel, resulting in excellent adsorption efficiency. Additionally, the nanocomposite maintains more than 80% phosphate adsorption efficiency even after ten adsorption-desorption cycles, indicating its recyclability and potential for repeated use. This compressible nanocomposite provides novel insights into the design of efficient phosphate removal cleaners and offers potential approaches for the functionalization of biomass-based composites.

Energy from Waste: Poterioochromonas malhamensis Used for Managing Dairy Effluent and Producing Valuable Microalgal Lipid

Currently, microalgae have become a marvelous and resource-friendly alternative source of advantageous bioproducts, such as lipids, carbohydrates, proteins, or other bioactive compounds. Because of the richness of microalgae in these high-value-added metabolites, still, it is an underdeveloped source of sustainable energy and food. There are some hurdles to profitable production, such as culture contamination and costly harvesting techniques. In the current work, a chrysophyte was isolated from dairy wastewater, identified as Poterioochromonas malhamensis based on its morphology and partial 18S rRNA gene sequences. This isolate was used to remediate dairy waste water (DWW) and to obtain neutral lipids (fatty acids) from microalgae. Microalgal growth was optimized by using different concentrations of DWW, supplemented with all the nutritive requirements for better progression and flourishment. Maximum biomass yield 1.478 g L−1 was achieved by optimized cultural conditions (different concentrations of DWW with BBM media). This strain showed high nitrate and phosphate removal efficiency (87.45% and 88.96%), respectively in 15 days. The experimental results highlighted that the lipid content and the chemical oxygen demand (COD) removal were 31.60% and 88.84%, respectively, and the lipid profile of isolated microalga was C16:0, C16:1, C18:0, C18:1, and C18:2 fatty acids. For growth and treatment purposes, 75% DWW with Bold’s Basal Medium (BBM) media showed better results. This is the first report of DWW treatment using the microalga Poterioochromonas malhamensis, as far as we are aware. Its cultivation prevented the spread of pollution of freshwater sources, remedied the DWW, and generated important lipids for industry.

Impact of Dissolved Oxygen on the Performance and Microbial Dynamics in Side-Stream Activated Sludge Hydrolysis Process

Dissolved oxygen (DO) plays an important role in the performance of biological wastewater treatment systems. This study investigated the effect of the DO concentration on nutrient removal performance and microbial community structure in side-stream activated sludge hydrolysis (SSH) and conventional anaerobic/anoxic/aerobic (A2O) processes. The results showed that the change in DO had little effect on the removal performance of chemical oxygen demand (COD), and the removal efficiencies were about 90% for both reactors. Compared with the high DO level (4.1–6.9 mg/L), the A2O and SSH reactors had better nitrogen removal performance at low (0.5–2.2 mg/L) and moderate (2.2–3.9 mg/L) DO levels, with ammonia (NH4+-N) removal efficiencies of 88–89% and 89–91%, respectively, and total nitrogen (TN) removal efficiencies of 74–76% and 75–81%, respectively. Directly reducing the DO concentration from high to low reduced the phosphate removal efficiencies of the A2O and SSH reactors from 80.2% and 86.2% to 63.1% and 70.6%, respectively, while re-elevating the DO concentration to moderate levels significantly improved the phosphate removal efficiencies to 94.6% and 96.0%, respectively. Compared to the A2O reactor, the SSH reactor had more stable and better nutrient removal performance under different DO conditions, partly due to the additional carbon sources produced through the sludge fermentation in the side-stream reactor. The decrease in the DO concentration resulted in a decrease in the relative abundance of Acinetobacter but an increase in the relative abundance of Competibacter, potentially leading to the deterioration in phosphorus removal.

A novel calcium peroxide/attapulgite-Fe(II) process for high concentration phosphate removal and recovery: Efficiency and mechanism

Phosphorus (P) has been overused in livestock farming, which inevitably results in high-concentration P-containing wastewater. Managing total phosphorus discharge is important to prevent eutrophication in aquatic environments, thus it is critical to develop new technologies for the removal and recovery of high-concentration phosphate. In this study, a novel calcium peroxide/attapulgite (CP/ATP) composite was developed and coupled with Fe(II) for high-concentration phosphate removal and recovery. The results demonstrated that the optimal dosage of the CP/ATP-Fe(II) process was CP/ATP = 0.25 g/L and Fe(II) = 2 mM. The pH effect on phosphate removal was minimal, while phosphate removal efficiency rose by 16.7% with the temperature increased from 10 °C to 25 °C. The co-existing ions exhibited little effect on phosphate removal, and the CP/ATP-Fe(II) process showed effective phosphate removal from the real piggery wastewater. The P content of the precipitates after phosphate removal by this process was as high as 25.82%, indicating its good potential for P recycling. A significant synergistic effect existed in CP/ATP and Fe(II) for phosphate removal, and the SEM-EDS, XRD, Raman and XPS characterization exhibited that the phosphate removal mainly relied on the in-situ-formed Fe(III) and the participation of calcium (Ca) species. Co-precipitation was the predominant mechanism for phosphate removal, and the proportions of Fe(III)–P, Ca–P and Ca–Fe(III)–P in the precipitates were 51.5%, 31.2% and 17.3%, respectively. This study provides a highly efficient process for phosphate removal and recovery from wastewater, and insights into interactions among phosphorus, iron and calcium.

Adsorption of Direct Orange 46 and phosphate ions on waste tomato stem ash used as a bio‐based adsorbent

AbstractIt is necessary to use adsorbents derived from natural materials, such as biosorbents since they do not any damage to the environment, for pollutants elimination that contaminate the aquatic environment. Since the deficiency in the literature was determined in the study in which only the adsorbent obtained from tomato stem was used before this study, a waste material with tomato stem was selected as a natural adsorbent without chemical compounds. Phosphate and dye contaminants, which are often present in industrial and municipal wastewater, were eliminated by adsorption process. Fourier transform infrared (FTIR), x‐ray fluorescence (XRF), Zeta potential, and scanning electron microscope (SEM) with energy dispersive x‐ray (EDX) spectroscopy were used to analyze tomato stems. The tomato stems resulted in high pollutants removal efficiencies recording 99.31% of phosphate () removal efficiency and 99.44% of Direct Orange 46 (DO 46) dye removal efficiency at optimal conditions. The best conditions for phosphate adsorption were pH = 6.0, 2.0 g/L of tomato stems concentration, 50 mg/L initial phosphate concentration and a contact time of 120 min resulting in an adsorption capacity of 4.24 mg/g. The best conditions for DO 46 adsorption were pH = 12, 2.0 g/L of adsorbent concentration, initial dye of 200 mg/L concentration and a contact time of 120 min (q = 13.76 mg/g). For both adsorption experiments, the adsorbent size was chosen to be less than 500 μm. As a result of the adsorption experiments on tomato stem ash, Freundlich isotherm (R2: 0.94) was suitable for DO 46 dye adsorption and Temkin isotherm (R2: 0.99) was suitable for elimination. The phosphate (R2: 0.97) and dye (R2: 1) adsorption onto tomato stem ash was explained using a pseudo‐second‐order kinetic model. It has been determined that the adsorption of the DO 46 dye with the tomato stem ash is an exothermic (∆H: −3.174) process that occurs naturally due to its nature (∆G: −8.41). On the other hand, it was determined that the adsorption of was spontaneous (∆G: −5.21) and endothermic (∆H: 5.7357). According to the adsorption results obtained in this study, it is appropriate to use the tomato stem, which is generated as waste, as an adsorbent. It is thought that obtaining from bio‐based waste in the removal of pollutants such as dye and phosphate in water will both reduce the cost and create an advantage in terms of biodegradability.

Performance of simultaneous carbon, nitrogen, and phosphorus removal from vegetable oil refining wastewater in an aerobic-anoxic sequencing batch reactor (OA-SBR) system by alternating the cycle times

Carbon (C), nitrogen (N), and phosphorus (P) pollutants are among the most common environmental contaminants in different types of industrial wastewater, and they are a pollution factor that causes the eutrophication of receiving aquatic systems. An aerobic-anoxic sequencing batch reactor (O/A-SBR) system was studied to enhance the efficiency of vegetable oil refining wastewater treatment (VORW). Reactors were exploited with a total cycle period of 24 h (20 min filling, 17 h aeration, 4 h anoxic, 2 h settling, 20 min draw, and 20 min idle). SBR efficiency was evaluated by measuring pH, turbidity, chemical oxygen demand (COD), biochemical oxygen demand (BOD5), and nutrients such as nitrate, ammonium, and phosphate. The results showed better performance from the start of operation with COD (83%), BOD5 (94%), turbidity (80%), nitrate (93%), ammonium (96%), and phosphate (91%) removal efficiencies. As industrial wastewater treatment is an important and complicated issue regarding environmental pollution, SBR can provide a better solution. The O/A-SBR system is a promising option that the VOR industry may adopt as a pre-treatment due to its more effective, inexpensive, and simple operation for organic matter and nutrient removal.

Non-radical dominated degradation of chloroquine phosphate via Fe-based O-doped polymeric carbon nitride activated peroxymonosulfate: Performance and mechanism

The utilization of peroxymonosulfate (PMS)-based advanced oxidation process as a proficient approach for treating wastewater has garnered significant attention. However, the activation of PMS and the degradation of contaminants are highly dependent on or severely limited by the design and structured active sites of catalysts. Herein, an Fe-based O-doped polymeric carbon nitride catalyst, namely Fe-ONLH, was synthesized to activate PMS for the efficient removal of model pollutant chloroquine phosphate (CQP) via a non-radical dominant pathway with singlet oxygen (1O2). The rapid degradation of CQP in the developed Fe-ONLH/PMS system was achieved by the optimum degradation conditions predicted by Response Surface Method (RSM) and the catalyst dosage was considered to have the highest relative importance among the variables. Particularly, the ability of Fe and oxygen co-dopants to generate non-radical active species is mainly attributed to the various active sites on Fe-ONLH (e.g., Fe-O, graphite N, CO and NC-N2), which also exhibited advantages in adaptability of wide pH range, catalyst reusability, stability in complicated ionic environmental or water matrixes. Besides, probable intermediates and decomposition pathways of CQP attacked by non-radicals and radicals were analyzed. The current study provides new insights of Fe-base heterogeneous catalysts for PMS activation and non-radical pathway degradation of pollutants during wastewater treatment.

A new insight in enhancing phosphate enrichment in biofilm process: Comparison of the key metabolic pathways in highly-efficient and dominant PAOs based on metagenomics

The formation of dominant phosphate-accumulating organisms (PAOs) is essential for the high enrichment of phosphate in biofilm sequencing batch reactors (BSBR) for phosphorus recovery. The dominant PAOs in the biofilm process have not been isolated and purified, and the key metabolic pathways that promote the formation of dominant PAOs are still unclear. In this study, four strains of highly-efficient PAOs were obtained by an innovative isolation procedure. The relationship between the abundance of highly-efficient and dominant PAOs and the phosphate removal ability was compared. We found that the abundance of PAOs was positively correlated with the phosphate removal efficiency in vitro pure culture and complex biofilm process. Metagenomics analysis revealed that compared with highly-efficient PAOs cultured in vitro, dominant PAOs in biofilms had unique key metabolic pathways, F-ATPases and N-Acyl homoserine lactones (AHLs). F-ATPases are important for maintaining the proton motive force (PMF) required for the uptake of carbon sources by PAOs, and AHLs are participating in phosphate metabolism through quorum sensing (QS) mediated secretion of extracellular polymeric substance (EPS). The formation of dominant PAOs was promoted by optimizing carbon source uptake and phosphate metabolism. This study revealed that the difficult isolation of dominant PAOs was due to the AHLs-mediated QS, and we identified the key pathways regulating the formation of dominant PAOs in biofilms through genomics analysis. Our findings provide insights in enhancing phosphate enrichment in BSBR by modulating the components of microbial community under the low concentration of carbon source consumption.

Fe-modified fly ash/cotton stalk biochar composites for efficient removal of phosphate in water: mechanisms and green-reuse potential.

Excessive phosphate content input into natural water can lead to the waste of resource and eutrophication. Biochar is a kind of low-cost adsorbent. However, its adsorption capacity for phosphate is low. In order to solve this problem, Fe compound-modified fly ash/cotton stalk biochar composites (Fe-FBC) were prepared through co-pyrolyzed fly ash and cotton stalk at 800℃, followed by infiltration of FeSO4 solution. The samples were characterized by scanning electron microscopy, Brunauer-Emmett-Teller, X-ray diffraction, Fourier transform infrared spectroscopy, and zeta potential. After modification, the hydrophilicity and polarity of Fe-FBC increased. In addition, the pore volume, specific surface area, and surface functional groups were significantly improved. The adsorption behavior of Fe-FBC for the removal of phosphate from water can be well fitted by the pseudo-second-order kinetic and Sips isotherm adsorption model, with a maximum adsorption capacity of 47.91mg/g. Fe-FBC maintained a high adsorption capacity in the pH range of 3-10. The coexisting anions (NO3-, SO42-, and Cl-) had negligible effects on phosphate adsorption. The adsorption mechanisms of Fe-FBC include electrostatic attraction, ligand exchange, surface complexation, ion exchange, chemical precipitation, and hydrogen bonding. Moreover, the desorption process of phosphate was investigated, indicating that the phosphate-saturated Fe-FBC could use as slow-release phosphate fertilizer. This study proposed a potentially environmental protection and recycling economy approach, which consists of recycling resources and treating wastes with wastes.

Effective removal of nitrogen and phosphorus from a black-odorous water by novel oxygen-loaded adsorbents

Black-odorous water, caused by hypoxia and overloading of nitrogen and phosphorus, is ubiquitous in global urban rivers. In this study, we developed oxygen-loaded adsorbents by loading oxygen into activated carbon, Attapulgite, Phoslock, and Muscovite via vacuum-pressure swing method, and investigated their aeration and removal efficiency of phosphate, ammonia nitrogen, and total nitrogen in black-odorous water. Results showed that the addition of oxygen-loaded coal-based columnar activated carbon (OCC) or oxygen-loaded Muscovite (OM) alone could increase the dissolved oxygen (DO) concentration at the sediment–water interface to more than 6 mg·L-1 on the first day, and OCC could maintain the high level of oxidation–reduction potential (ORP) (up to + 327 mV) for 15 days. Most oxygen-loaded adsorbents remarkably reduced phosphate in water, essentially from 0.27 mg·L-1 to < 0.05 mg·L-1. Additionally, ammonia nitrogen and total nitrogen were reduced by more than 50 % by adding materials after oxygen loading treatment. The 16 s RNA results showed that Dechloromonas was dominant in abundance, and the reduction of nitrogen was mainly affected by microbial activity. Our results provided a series of oxygen-loaded adsorbent materials with potential engineering applications for rapid treatment of urban black-odorous water.

Highly efficient and selective removal of phosphate from wastewater of sea cucumber aquaculture for microalgae culture using a new adsorption-membrane separation-coordinated strategy

Highly efficient and selective removal of phosphate from wastewater of sea cucumber aquaculture for microalgae culture using a new adsorption-membrane separation-coordinated strategy

Titanium dioxide nanoparticles functionalized chitosan toward bio-based antibacterial adsorbent for enhanced phosphate capture

Developing an eco-friendly, sustainable and antibacterial adsorbent is significant for actual water treatment. Herein, a bio-based antibacterial adsorbent based on titanium dioxide (TiO2) nanoparticles functionalized chitosan (CS) was prepared through an in-situ hydrolysis strategy using titanium oxysulfate as the source of TiO2. The as-obtained CS/TiO2 nanocomposite was characterized by a variety of analytical techniques. According to the Langmuir mode, the adsorption capacity of CS/TiO2 reached 23.64 mg P g−1, almost 8 times higher than that of CS. In addition, the normalized adsorption capacity (adsorption value per Ti) of CS/TiO2 was calculated to be 102.68 mg P g−1 Ti−1, much higher than pure TiO2 (60.11 mg P g−1 Ti−1). Moreover, CS/TiO2 exhibited a highly selective capacity for phosphate removal in the presence of competing anions, and showed high stability in a wide pH range of 3.0–8.0. When the phosphate concentration was 2.0 mg P L−1, the removal efficiency of phosphate reached 99.5 % and the residual concentration was only 10 μg P L−1, which meets the USEPA standards for eutrophication prevention and control. In addition, after treatment by CS/TiO2, the phosphate concentration of two sewage water samples decreased from 1.50 and 1.0 mg P L−1 to <0.10 mg P L−1, meeting the standard of level II water based on the Environmental Quality Standard of China (GB3838–2002). Ligand exchange and electrostatic interactions are mainly responsible for phosphate adsorption by CS/TiO2. Furthermore, the CS/TiO2 nanocomposites exhibited excellent antibacterial activity, which could avoid biofouling contamination caused by microorganisms. Benefiting from the above advantages, the as-designed CS/TiO2 nanocomposite has great potential as a bio-based antibacterial adsorbent for phosphate capture or removal from wastewater.

Organics and Nutrient Transformation in a Microbial Fuel Cell Influenced by Antibiotics

AbstractThe present research focuses on the effect of the highly toxic and broad‐spectrum bacteriostatic antibiotic pollutant, tetracycline (TC) as a sole electron donor and co‐electron donor on the operational efficacy of a microbial fuel cell (MFC) in terms of nutrient and pollutants removal. It is observed that the removal efficiency of the MFC increases by the gradual increase in TC concentration (5–30 mg L−1). The maximum removal efficiency (59%), voltage production (372 mV), power density (81.4 mW m−2), and current density (232.5 mA m−2) are achieved in the MFC with 25 mg L−1 of TC. Moreover, the influential role of TC as a co‐substrate is also investigated using three substrates viz, acetic acid, sucrose, and albumin. The current results suggest that chemical oxygen demand (COD) removal efficiency, coulombic efficiency, and voltage output of each substrate are inversely proportional to the amount of TC and are in the order of acetic acid &gt; sucrose &gt; albumin. The nutrient removal efficiency of the MFC decreases with an increase in TC concentration, i.e., when TC is increased from 10 to 50 mg L−1, the nitrogen removal efficiency decreases from 78% to 38%, the sulfur removal efficiency decreases from 79% to 32%, and the phosphorous removal efficiency decreases from 72% to 24%. The results suggest that an MFC can be upgraded for large‐scale biological processes for antibiotic pollutant removal. Moreover, the adverse effect of TC in power generation of an MFC can serve as a biosensor for biological wastewater treatment processes to detect the antibiotic toxicity.

Understanding the process of phosphate removal in Fe0/H2O systems using the methylene blue method

The removal mechanisms of contaminants in Fe0/H2O are still poorly understood, and characterized by contradictory findings. Therefore, the present study aims to improve the understanding of the processes involved in phosphate removal in Fe0/H2O system. Herein, the methylene blue method (MB method) is used to trace the dynamics within the investigated systems. The MB method utilizes the differential adsorptive affinity of MB onto sand and sand coated with iron corrosion products to evaluate the degree of Fe0 corrosion in Fe0/H2O systems. The extent of MB discoloration and phosphate removal in various Fe0-based systems was characterized in parallel quiescent batch experiments for two weeks and two months. Parallel experiments with Orange II (O-II) as a model contaminant allowed an improved discussion of the results. The investigated systems were: (i) Fe0 alone, (ii) MnO2 alone, (iii) sand alone, (iv) Fe0 + sand, (v) Fe0 + MnO2, and (vi) Fe0 + sand + MnO2. Additional experiments were conducted to test the influence of Fe0 type, Fe0 and sand mass loadings on dye discoloration and phosphate removal in Fe0/sand system. Each system was characterized by: (i) pH value, (ii) Fe concentration, (iii) dye discoloration (MB, O-II), and (iv) phosphate concentration. Results showed that the MB method was capable of tracing the extent of iron corrosion in the various investigated systems and clarified the role of in-situ generated iron corrosion products (FeCPs) in the removal of phosphate. The suitability of mixing sand aggregates with Fe0 for efficient phosphate removal is demonstrated through the MB method. Overall, the appropriateness of the MB method to characterize the dynamics of Fe0/H2O systems is validated.