•FCDI was explored for phosphorus removal and recovery from low-strength wastewaters.•Operational conditions were systematically investigated.•Enrichment experiments were conducted to obtain a ...concentrated phosphorus stream.
Phosphorus (P) concentrations as low as 10 mg/L P can lead to eutrophication in natural waters. Meanwhile, phosphorus is an important and non-renewable resource for humans, animals and plants. This study investigated the removal and recovery of phosphorus from low-strength wastewaters by flow-electrode capacitive deionization (FCDI) to realize the sustainable utilization of phosphorus. Effects of different operating parameters on the performance of FCDI for phosphorus removal were systematically studied, including applied voltage, flow rate and flow direction of feed water, initial phosphorus concentration, carbon black content and initial pH value. Results showed that the applied voltage and initial pH value had great influence on the phosphorus removal efficiency. The removal efficiency of phosphorus reached about 97% when the operating parameters were optimized. The FCDI system possessed good removal performance of phosphorus after six consecutive cycling tests. In addition, the low concentration of feed phosphorus solution (100 mg/L P) could be effectively concentrated by 16 times after 11 h of operation through the enrichment experiment, leading to a final concentration of 16.8 mg/L P in feed solution and 1567 mg/L P in the aqueous phase of flow electrodes. To conclude, these results revealed that FCDI system is effective in phosphorus removal and recovery, and has great application prospects in treatment of phosphorous wastewaters.
This paper presents a pilot scale study of an algal-based sewage treatment and resource recovery (STaRR) system capable of treating municipal sewage and recovering its nitrogen- and ...phosphorous-content as fertilizer. Core components of the STaRR system include i) mixotrophic cultivation of algal biomass in settled sewage; ii) hydrothermal liquefaction (HTL) of the resulting algal biomass, and iii) processing of the products of HTL to recover energy in the form of biocrude and nutrients in the form of struvite. Performance of a pilot-scale STaRR system in recovering nitrogen (N) and phosphorus (P) from settled sewage as struvite is documented and compared with that of existing and emerging technologies. Nutrient removal per unit energy input in the STaRR system is estimated as 257.1 g N/kWh and 36.6 g P/kWh while that in eight full-scale sewage treatment plants (STPs) averaged 74.3 g N/kWh and 135.1 g P/kWh. Energy required to treat primary effluent in the STaRR system (531.5 kWh/MG) is estimated to be lower than the average in the 8 STPs (1,037.9 ± 503.3 kWh/MG). While existing technologies had been originally designed for removal of nutrients rather than any recovery, a review of the literature revealed 12 emerging technologies for nutrient recovery. Nutrient recovery performance of the STaRR system (5.9% N and 71.6% P) is shown to be superior to that of those 12 emerging technologies. Recoveries recorded in the STaRR system translate to a yield of 2.4 kg struvite per 100 m3 of primary effluent. Results of this study imply that the STaRR system deserves due consideration as a greener and sustainable pathway for nutrient removal and recovery from sewage.
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•Demonstrated removals of 257.1 g N/kWh and 36.6 g P/kWh by algal system.•Algal system can recover ∼70% of P and ∼6% of N in settled sewage.•Algal system can recover 2.4 kg struvite/100 m3 of settled sewage.•Demonstrated higher nutrient recovery by algal system than emerging technologies.
Accumulation of inorganic and labile organic phosphorus (P) in intensive agricultural systems leads to P loss from soil which can cause serious environmental problems. Soil microbes are important in ...mobilizing soil non‐available P, however, little is known about the role of soil microbes in immobilizing P to reduce P loss. Here, we test whether stimulating microbial biomass to immobilize P could reduce the amount of labile P available for leaching. The distribution characteristics of Olsen P, organic P and microbial biomass P were determined in three intensive agricultural systems. In addition, we conducted a pot experiment with three P and four carbon (C) levels. CaCl2 extractable P was measured and used to indicate the risk of P leaching. We found that there was a positive relationship between soil organic C and microbial biomass P. Carbon addition drove the process of P immobilization and reduced CaCl2 extractable P. Microbial biomass P increased by 64% (p < .05) with the addition of C, and Olsen P and CaCl2 extractable P decreased by 28% and 17%, respectively. Our results show that C addition increased microbial immobilization of P and reduced forms of labile P susceptible to leaching. Stimulating microbes to immobilize P by adding C to soils may have the potential to reduce P loss from intensive agricultural systems, reducing their environmental impact.
Phosphate-solubilizing bacteria represent a bioalternative in making soil-immobilized phosphorus (P) available to plants, and consequently improve agriculture sustainability and reduce nutrient ...pollution. In this study, we examined whether
Rhizobium
sp. B02 inoculation can affect the soil P fractions. Moreover, we investigated how inoculation influences the growth, physiological traits, and productivity of the maize crop. Field tests were carried out to evaluate the combined application of strain B02 and reduced doses of P fertilizer. Soil P fractionation was performed after crop harvesting, assessing the P dynamics. To study the plant response, samplings were carried out in three phenological stages—the vegetative stage of the 7 fully emerged leaves with leaf collars (V7), the vegetative stage of the tassel (VT), and the reproductive stage of physiological maturity (R6). Using 50% of P fertilizer recommended, the strain inoculation increased the labile inorganic P fraction by 14% compared to the control treatment at the same dose, indicating that it favored the Pi mobility. Under these same conditions in the V7 and VT phenological stages, the inoculation significantly improved shoot length (28 and 3%) and shoot dry weight (9.8 and 12%). B02 inoculation increased grain yield by 696 kg ha
−1
using 50% of the recommended rate of P fertilizer, phenocopying the complete P fertilization treatment without inoculation. Therefore,
Rhizobium
sp. B02 inoculation replaced 50% of P fertilizer in maize and increased the soil P availability.
Un-restored (R0) and restored (in 2006 (R2006) and in 2002, (R2002)) coastal wetlands were selected to study phosphorus (P) storage capacity and the risk of P loss in the Yellow River Delta (YRD). ...The results showed that the maximum P sorption capacity (Qmax) in the wetland sediments varied between 201.8–1168.6 mg kg−1; the average value was 576.2 mg kg−1. Qmax increased with increasing time since restoration (R2002 > R2006 > R0). The eutrophication risk index (ERI) ranged between 0.27–2.07% and decreased with increasing time since restoration, but the relationship was not statistically significant (P > 0.05). A correlation analysis demonstrated that Feox, Mg, and Alox are the main P sorption agents in wetland sediments, whereas TOC, pH, and clay particles have an important effect on P sorption and release. The analysis suggests that we should restore degraded coastal wetlands to help reduce the P load to offshore waters.
•Phosphorus sorption increased with coastal wetland restoration in Yellow River Delta, China.•T he Feox、Mg、and Alox content dominanted phosphorus sorption in Yellow River Delta sediments.•Restored wetlands can be used for phosphorus reduction at coastal zone.
The crystallization of struvite in fluidized-bed crystallizer (FBC) was performed to treat synthetic wastewaters that contain phosphorous. Under optimal conditions (pH 9.5, molar ratio ...Mg/N/P = 1.3/4/1, struvite seed dose (53–297 μm) = 30 g L−1, total flow rate = 12 ml min−1, reflux = 120 ml min−1), the removal of phosphate (PR) and the crystallization ratio (CR) were 95.8% and 93.5%, respectively. Based on a thermodynamic prediction, the supersaturation, which was obtained from the difference between the theoretical solubility and phosphate concentration, predominated the crystallization efficiency and the properties of the struvite pellets, such as their morphology, particle size and apparent density. Coexisting ions NO3− (80, 160 ppm), CH2COOH− (260, 520 ppm), F− (650, 1300 ppm) and SO42− (650, 1300 ppm), were utilized to prepare P-containing wastewaters. Of these ions, SO42− (1300 ppm) remarkably reduced the capability of FBC to remove phosphate from solution. In the presence of NO3− and CH3COO− (for synthesizing TFT-LCD wastewater), and F− and SO42− (for synthesizing semiconductor wastewater), CR% was lower than in pure water, although the ultimate PR% did not differ significantly.
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•Phosphorus in water was recovered as homogeneous struvite crystals in a FBC reactor.•Effects of pH, co-existing ions and P concentration on FBC efficiency were tested.•pH was a major factor influencing struvite crystallization.•Removal of phosphate and crystallization ratio were optimized at a β of 2.98.•The co-existing ions modified morphology of struvite pellets.
The purpose of the work detailed here was to determine the impact of the distribution of natural organic matter and grain size on the resources and distribution of mobile phosphorus in the bottom ...sediments of small reservoirs located in catchments subject to different levels of anthropopressure. The research objects were five small reservoirs located in southeast Poland. In small retention reservoirs, it is the anthropogenic impact of the catchment and its geological structure, and to a lesser extent sediment granulation, that determine the distribution of phosphorus fractions (especially in inorganic compounds) and the share of total P they account for. In general, a higher level of contamination of sediments with organic matter (OSI
ON
increase) is shown to be associated with a higher content of the organic fraction of phosphorus and easily decomposable organic matter. Within small retention reservoirs under significant anthropogenic influence from the catchment, sandy sediments compared with silty sediments were significantly less loaded with potentially mobile phosphorus as well as with organic forms of phosphorus and (sometimes) nitrogen. The occurrence of humic-metal-phosphate complexes is determined by there being sufficient organic matter, especially humic fractions. Fractions of inorganic phosphorus compounds and organic matter have the terrigenous source of these pollutants in common. The organic sediment index can serve as an adjunctive indicator with which to assess the potential ability of the sediments in small retention reservoirs to internal supply of the water column in nutrients.
Graphical abstract Highlights ► SFA can aid sustainable P management in response to P scarcity and pollution. ► 18 recent P SFAs are assessed at different scales to identify P ‘hotspots’. ► ...Context-specific analyses are important to quantify P flows in a given system. ► Regardless of scale, P is lost from all sectors between mine, field and fork. ► Losses in the mining/fertilizer and food processing sectors must not be overlooked. ► P use efficiency and recovery is needed in mining, agriculture, food, household and waste sectors.
Black phosphorus (BP), a star‐shaped two‐dimensional material, has attracted considerable attention owing to its unique chemical and physical properties. BP shows great potential in photocatalysis ...area because of its excellent optical properties; however, its applications in this field have been limited to date. Now, a Z‐scheme heterojunction of 2D/2D BP/monolayer Bi2WO6 (MBWO) is fabricated by a simple and effective method. The BP/MBWO heterojunction exhibits enhanced photocatalytic performance in photocatalytic water splitting to produce H2 and NO removal to purify air; the highest H2 evolution rate of BP/MBWO is 21042 μmol g−1, is 9.15 times that of pristine MBWO and the NO removal ratio was as high as 67 %. A Z‐scheme photocatalytic mechanism is proposed based on monitoring of .O2−, .OH, NO2, and NO3− species in the reaction. This work broadens applications of BP and highlights its promise in the treatment of environmental pollution and renewable energy issues.
A Z‐scheme heterojunction of 2D/2D black phosphorus/monolayer Bi2WO6 was fabricated with enhanced photocatalytic performance under visible light irradiation. The highest NO removal ratio was up to 67 % and the H2 evolution ratio 21 042 μmol g−1. The black phosphorus nanosheets can be used for photocatalytic degradation of exhaust gases in air.
The activation of white phosphorus by main group elements and compounds is discussed. White phosphorus, extracted from phosphate minerals, is a critical raw material for many industrial products.
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