scholarly journals Improvement of phosphorus release from sludge by combined electrochemical-EDTA treatment

2021 ◽  
Vol 83 (8) ◽  
pp. 1824-1833
Author(s):  
Yunfeng Xu ◽  
Fanglu Hu ◽  
Xin Wang ◽  
Yangwei Qu ◽  
Lu Xu ◽  
...  
Keyword(s):  
Metal Ions ◽  
Extracellular Polymeric Substances ◽  
Ethylenediaminetetraacetic Acid ◽  
Organic Phosphorus ◽  
Electrochemical Treatment ◽  
Phosphorus Release ◽  
Dissolved Phosphorus ◽  
Sludge Flocs ◽  
Edta Treatment ◽  
Reactive Phosphorus

Abstract In this paper, combined with the addition of ethylenediaminetetraacetic acid (EDTA), the electrochemical treatment of waste activated sludge (WAS) was investigated to explore its effect on the release of phosphorus (P) from WAS. The results showed that during the electrochemical treatment, the addition of EDTA could significantly promote the release of P from the WAS to the supernatant, the optimal amount of EDTA was 0.4 g/g total suspended solids (TSS), when the release of total dissolved phosphorus (TDP), organic phosphorus (OP) and molybdate reactive phosphorus (PO43−-P) were 187.30, 173.84 and 13.46 mg/L, respectively. OP was the most likely form of P to be released during this process. Moreover, combined electrochemical-EDTA treatment could promote the release of P and metal ions from extracellular polymeric substances (EPSs) to the supernatant, and increase the solubility and disintegration of sludge. EDTA chelated the metal ions of sludge flocs and phosphate precipitates to cause sludge floc decomposition, thereby promoting the release of P from WAS.

Assessing Bioavailability of Typical Lakes and Reservoirs in Northeast China Based on Phosphorus Fractions

2021 ◽  
pp. 1-11
Author(s):  
Junqiu Wu ◽  
Yue Zhao ◽  
Ran Zhao ◽  
Liming Jia ◽  
Zimin Wei
Keyword(s):  
Microbial Biomass ◽  
Organic Phosphorus ◽  
Mineralization Rate ◽  
Dissolved Phosphorus ◽  
Positive Effects ◽  
Algae Blooms ◽  
Dissolved Reactive Phosphorus ◽  
Lakes And Reservoirs ◽  
Concentration Changes ◽  
Reactive Phosphorus

To explore the eutrophication degree in the typical lakes and reservoirs of the northeast region of China, the bioavailability of dissolved organic phosphorus (DOP) of the lakes has been examined in this study. The laboratory incubation was carried out at 20 °C for 55 days and the concentrations of total dissolved phosphorus (TDP), dissolved reactive phosphorus (DRP), DOP and the microbial biomass have been detected. Results showed that, during the process of incubation, the concentrations of TDP and DRP were increased, whereas the DOP was decreased, which leads to the decreased mineralization rate. In addition, the changes of microbial biomass were fluctuant, but they had significantly positive effects on the concentration changes and mineralization rate of DOP (p < 0.05). The correlation analysis among the phosphate fractions showed that the TDP significantly promoted the DRP concentration, mineralization rate of DOP and the cumulative mineralization of DOP. The kinetics model was conducted to predict the further mineralization of DOP and to analyze the pollution degree of the eight lakes and reservoirs. Accordingly, the lakes with high DRP and TDP had worse water quality and are prone to algae blooms.

Freeze–thaw combined with activated carbon improves electrochemical dewaterability of sludge: Analysis of sludge floc structure and dewatering mechanism

2021 ◽  
Author(s):  
Kai Hui ◽  
Lei Song ◽  
Zhenzhou Yin ◽  
Hongwei Song ◽  
Zehao Wang ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Extracellular Polymeric Substances ◽  
Combined Treatment ◽  
Electrochemical Treatment ◽  
Sludge Dewatering ◽  
Element Analysis ◽  
Sludge Flocs ◽  
Freeze Thaw ◽  
Floc Structure ◽  
Sludge Cake

Abstract Freeze–thaw (F/T) and electrochemistry are environment-friendly and efficient sludge treatment technologies. In this study, F/T and electrochemistry were combined in the pretreatment of sludge dewatering in the laboratory, and activated carbon (AC) was added to improve the electrochemical dewatering performance of sludge. During the experiment, the effect of F/T on the floc structure was analyzed by a laser particle analyzer and scanning electron microscope. F/T treatment not only improved the dewatering performance of sludge, but also promoted the aggregation of sludge flocs into larger particles. The median diameter (D50) increased from 45.27 µm to 128.94 µm. Then, the intracellular polymer of large-particle sludge was analyzed by three-dimensional excitation–emission matrix (3D-EEM). The tightly bound extracellular polymeric substances (TB-EPS) still contained a large amount of protein substances, which hindered the improvement of sludge dewatering performance. AC was added to the thawed sludge solution before electrochemical treatment (EP). The conductivity of AC enhanced the effect of EP, thereby cracking the sludge flocs. Thus, the light intensity of TB-EPS in the 3D-EEM fluorescence spectroscopy was decreased, and the D50 was also reduced to 105.3 µm. The final specific resistance of filtration and water content were reduced by 96.39% and 32.17%, respectively. Element analysis of the sludge cake after dehydration showed that the addition of AC significantly improved the combustion efficiency of the sludge cake. Moreover, preliminary economic analysis showed that the cost of this research was low, which indicated the potential application value of combined treatment.

Bioadsorption of Multiple Heavy Metal Ions by Rhizophora Apiculate sp. and Elaesis Guineensis sp.

2017 ◽  
Vol 14 (1) ◽  
pp. 15
Author(s):  
M.B. Nicodemus Ujih ◽  
Mohammad Isa Mohamadin ◽  
Milla-Armila Asli ◽  
Bebe Norlita Mohammed
Keyword(s):  
Heavy Metal ◽  
Metal Ions ◽  
Removal Efficiency ◽  
Heavy Metal Ions ◽  
Agricultural Waste ◽  
Living Organism ◽  
Heavy Metal Concentration ◽  
Industrial Area ◽  
Electrochemical Treatment ◽  
Chemical Oxidation

Heavy metal ions contamination has become more serious which is caused by the releasing of toxic water from industrial area and landfill that are very harmful to all living organism especially human and can even cause death if contaminated in small amount of heavy metal concentration. Currently, peoples are using classic method namely electrochemical treatment, chemical oxidation/reduction, chemical precipitation and reverse osmosis to eliminate the metal ions from toxic water. Unfortunately, these methods are costly and not environmentally friendly as compared to bioadsorption method, where agricultural waste is used as biosorbent to remove heavy metals. Two types of agricultural waste used in this research namely oil palm mesocarp fiber (Elaesis guineensis sp.) (OPMF) and mangrove bark (Rhizophora apiculate sp.) (MB) biomass. Through chemical treatment, the removal efficiency was found to improve. The removal efficiency is examined based on four specification namely dosage, of biosorbent to adsorb four types of metals ion explicitly nickel, lead, copper, and chromium. The research has found that the removal efficiency of MB was lower than OPMF; whereas, the multiple metals ions removal efficiency decreased in the order of Pb2+ > Cu2+ > Ni2+ > Cr2+.

scholarly journals Seasonal Variations of Phosphorus Species in the Overlying and Pore Waters of the Tuohe River, China

2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
Qing Xu ◽  
Xiaoping Yu ◽  
Yafei Guo ◽  
Tianlong Deng ◽  
Yu-Wei Chen ◽  
...  
Keyword(s):  
Seasonal Variations ◽  
Yangtze River ◽  
Algal Bloom ◽  
Soluble Reactive Phosphorus ◽  
Pore Waters ◽  
Phosphorus Species ◽  
Dissolved Phosphorus ◽  
Vertical Distributions ◽  
Reactive Phosphorus ◽  
Main Factor

Overlying sediment and pore waters were collected in summer and winter at upstream (Jintang) and downstream (Neijiang) sites of the Tuohe River, which is one of the five largest tributaries of the Yangtze River in China. Phosphorus species, including soluble reactive phosphorus (SRP), soluble unreactive phosphorus (SUP), and total dissolved phosphorus (TDP), and some diagenetic constituents including dissolved Fe(II), Mn(II), and sulfide in overlying and pore waters, were measured systematically. The seasonal variations and vertical distributions of phosphorus species in overlying and pore waters at both sampling sites were obtained to elucidate some aspects of the transport and transformations of phosphorus. Based on the profiles of pore and overlying waters as well as the TDN/TDP data during an algal bloom in 2007, it was clearly demonstrated that phosphorus was the main factor limiting the phytoplankton growth in the Tuohe River.

Relevance of microbial extracellular polymeric substances (EPSs) - Part II: Technical aspects

2001 ◽  
Vol 43 (6) ◽  
pp. 9-16 ◽  
Author(s):  
H.-C. Flemming ◽  
J. Wingender
Keyword(s):  
Metal Ions ◽  
Extracellular Polymeric Substances ◽  
Organic Molecules ◽  
Wastewater Sludge ◽  
Resistance Change ◽  
Biotechnological Potential ◽  
Oil Drilling ◽  
Friction Resistance ◽  
Drilling Muds ◽  
Dissolution Of Minerals

Extracellular polymeric substances (EPSs) are involved in both detrimental and beneficial consequences of microbial aggregates such as biofilms, flocs and biological sludges. In biofouling, they are responsible for the increase of friction resistance, change of surface properties such as hydrophobicity, roughness, colour, etc. In biocorrosion of metals they are involved by their ability to bind metal ions. In bioweathering, they contribute by their complexing properties to the dissolution of minerals. The EPSs represent a sorption site for pollutants such as heavy metal ions and organic molecules. This can lead to a burden in wastewater sludge; on the other hand, the sorption properties can be used for water purification. Other biotechnological uses of EPS exploit their contribution to viscosity, e.g., in food, paints and oil-drilling ‘muds’; their hydrating properties are also used in cosmetics and pharmaceuticals. Furthermore, EPSs may have potential uses as biosurfactants, e.g., in tertiary oilproduction, and as biological glue. EPSs are an interesting component of all biofilm systems and still hold a large biotechnological potential.

scholarly journals Phosphorus dynamics in the water of tropical semiarid reservoirs in a prolonged drought period

2018 ◽  
Vol 30 (0) ◽  
Author(s):  
Herika Cavalcante ◽  
Fabiana Araújo ◽  
Vanessa Becker
Keyword(s):  
Water Column ◽  
Organic Phosphorus ◽  
Soluble Reactive Phosphorus ◽  
Particulate Phosphorus ◽  
Semiarid Region ◽  
Drought Period ◽  
Chl A ◽  
Dissolved Phosphorus ◽  
Phosphorus Dynamics ◽  
Prolonged Drought

Abstract Aim To verify the vertical distribution of phosphorus in the water and to identify the predominant forms of P in the water column for understand the phosphorus dynamics in tropical semiarid reservoirs during a prolonged drought period. Methods Two reservoirs from the semiarid region of Rio Grande do Norte were analysed during the period from May 2015 to June 2016. Were analysed: Suspended solids (SS), chlorophyll a (Chl-a), dissolved oxygen (OD) and temperature. Vertical profiles were plotted for total phosphorus (PT), total dissolved phosphorus (PTD), particulate phosphorus (PP), dissolved organic phosphorus (POD) and soluble reactive phosphorus (FRS). Results The phosphorus values distributed in the water column were high for both reservoirs, presenting the highest values during the periods with lower depth. Gargalheiras presented greater predominance of PT and PP, while Cruzeta had the highest values of FRS. Chl-a and SS values were also consistent with phosphorus values: Chl-a was higher in Gargalheiras, while SS, mainly inorganic, were higher in Cruzeta. Gargalheiras presented anoxic conditions close to the sediment from May 2015 to December 2015, which may induce the release of phosphorus from the sediment to the water column. Values that are too high during the shallower months, especially in Cruzeta, may have been influenced by the release of P from sediment through wind resuspension. Conclusions The amounts and predominant types of phosphorus in the water column are of great importance to understand the phosphorus dynamics and will support restoration plans for the studied environments. In this study it was possible to verify that the reservoirs are susceptible to the release of P from the sediment due to the environmental conditions, mainly low depths, resuspension of the wind and anoxia in the hypolimnion.

scholarly journals The Biological methods of selenium nanoparticles synthesis, their characteristics and properties

2020 ◽  
pp. 6-20
Author(s):  
O. Tsehmistrenko
Keyword(s):  
Metal Ions ◽  
Green Synthesis ◽  
Alternative Energy ◽  
Extracellular Polymeric Substances ◽  
Crop Yields ◽  
Production Optimization ◽  
Total Charge ◽  
Coating Agent ◽  
Synthesis Of Nanoparticles ◽  
Biological Methods

Nanotechnologies have an impact on every sphere of life, change approaches to environmental recovery, introduce new methods of disease analysis and prevention, treatment, drug delivery and gene therapy, affect the provision of environmentally friendly alternative energy sources, increase crop yields, animal and poultry productivity. Physical, chemical, biological methods of synthesis of nanoparticles, selenium in particular, their properties and the factors participating in reduction of metal ions to nanoparticles are considered. Limitations of nanoparticle synthesis inherent in the biological method (identification and isolation of bioactive fragment responsible for biomineralization of metal ions, analysis of ways to develop individual nanoparticles) and factors contributing to the intensification of nanoparticle production (optimization of pH, temperature, contact time, mixing degree) changes in the total charge of functional organic molecules on the cell wall). It has been proved that these factors affect the size, morphology, composition of nanoparticles and their efficiency during the synthesis. The model of green synthesis with the use of physicochemical means and their biomedical applications have been summarized. There are organisms used for the synthesis of NPs - terrestrial and marine bacteria, bacterial extracellular polymeric substances as bioreductants, fungi, yeast, algae, viruses, microorganisms. It has been demonstrated the biochemical ways of microorganisms in order to fight the toxicity of metals during the synthesis of nanoproducts and the factors that determine the toxicity of metals that are converted into nanoparticles (size, shape, coating agent, nanoparticle density and type of pathogen). The biological role of selenium and features of its influence on an organism in a nanoscale scale are shown. Key words: nanotechnologies, nanoselenium, bacteria, green synthesis, enzymes.

Influence of calcium and EDTA on copper ion bioavailability in copper nanoparticle toxicity tests improves understanding of nano-specific effects

2020 ◽  
Vol 36 (7) ◽  
pp. 467-476
Author(s):  
Halis Boran
Keyword(s):  
Acute Toxicity ◽  
Metal Ions ◽  
Ethylenediaminetetraacetic Acid ◽  
Scale Effects ◽  
Copper Ion ◽  
Chelating Agent ◽  
Aquatic Organisms ◽  
Toxicity Tests ◽  
Cu Toxicity ◽  
Cu Ions

Metal-based nanoparticles (NPs) can release metal ions that are toxic to aquatic organisms; however, whether the toxicity is from metal ions rather than unique “nano-scale” effects of the NPs is unresolved. The present study aimed to compare the toxicity of Cu2+ and Cu-NPs in larval zebrafish ( Danio rerio) to clarify whether toxic effects are attributable to release of Cu ions and to determine the effect of the chelating agent ethylenediaminetetraacetic acid (EDTA) and calcium hardness (as CaCO3) on the Cu toxicity. First, the acute toxicity (96-h lethality) of Cu-NPs was determined in comparison to aqueous Cu in larvae exposed to CuSO4, and subsequently, sublethal tests with Cu-NPs and CuSO4 were conducted with additions of EDTA or calcium ions to evaluate alterations in expression of metallothionein-2 ( MT2) gene transcripts (quantitative real-time polymerase chain reaction). Acute toxicity of Cu in larvae exposed to CuSO4 was greater (LC50 = 226 µg Cu/L) than for larvae exposed to Cu-NPs (LC50 = 648 µg Cu/L). The expression of MT2 increased with Cu concentration ( p < 0.05), and the slope of the linear regression was significantly greater in fish exposed to CuSO4 (slope = 0.090) compared to Cu-NPs (slope = 0.011). Cu2+ was 2.9-fold more toxic than Cu-NPs. The presence of 5 mg/L EDTA and 220 mg/L CaCO3 significantly reduced the expression of MT2 (1.8-fold for EDTA, 2.3-fold for CaCO3) in larvae exposed to CuSO4. For larvae exposed to Cu-NPs, the presence of EDTA reduced the expression of MT2 (1.7-fold) relative to Cu-NP concentration. While Cu-NPs induced MT2 expression, the differences in concentration relationships of MT2 expression between Cu-NPs and CuSO4 indicated that factors other than release of Cu ions from Cu-NPs influenced acute toxicity of Cu-NPs. The conclusion drawn from this ecotoxicological risk assessment was that EDTA and calcium significantly decreased Cu toxicity in freshwater fish.

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