Standards , Measurements And Testing Research Articles

Synergistic application of alum sludge and sequential extraction for phosphorus recovery from sewage sludge char

Phosphorus (P) recovery from sewage sludge (SS) (or its ash/char) is challenging due to the presence of heavy metals (HMs) in SS. This study proposed the integration of SS, alum sludge (AS), sequential wet extraction, and pyrolysis for P recovery without simultaneous HM extraction. SS + AS mixture (P:Al molar ratio = 3:1) was first acid pretreated to obtain amended SS, then pyrolyzed, and finally, P was extracted from the char using an alkali. Pyrolysis was conducted at low (400 °C), medium (600 °C), and high (900 °C) temperatures. The highest alkaline P recovery efficiency was 88 % from the amended SS char, while 32 % from the unamended SS char (both prepared at 400 °C). Overall, the highest P recovery in the amended process was 48 % higher than the unamended process despite 11 % P loss during acidic pretreatment. Standards measurements and testing (SMT) protocol and solid-state NMR (31P and 27Al) analyses revealed that acidic pretreatment of SS with AS induced apatite phosphate (AP) to non-apatite inorganic phosphate (NAIP) conversion in SS. As NAIP is more soluble in alkali than AP and HMs, higher alkaline P recovery was achieved for amended SS char than unamended SS char, without HM contamination. However, higher pyrolytic temperatures impaired P recovery due to the immobilization of P in the char carbon matrix and the formation of recalcitrant P phases. These findings were corroborated by complementary characterization techniques such as XPS, XRD, and FTIR. Some major HMs in SS and AS were concentrated in char, except Zn, which partially volatilized above 600 °C. This study demonstrated the applicability of AS for extracting P from SS, offering a potential pathway for the synergistic management of sludge waste streams.

A novel Electrolysis-integrated anammox system for intensified nitrogen removal and simultaneous phosphorus recovery as vivianite

A novel electrolysis-integrated anammox (Ele-anammox) process was developed for intensified nitrogen removal and concomitant phosphorus recovery from nutrient-rich wastewater. By conducting a parallel experiment, average removal efficiencies of total nitrogen (TN) and total phosphorus (TP) in Ele-anammox reactor reached 90.69% and 95.02% respectively, showing increases of 7.76% and 79.08%, as compared to the traditional anammox process. Anammox reaction and synergetic denitrification were mainly responsible for the reinforced N-removal. Successions of microbial communities revealed that Candidatus Kuenenia declined markedly while Candidatus Brocadia was enriched in Ele-anammox system, suggesting that electrical environment provided Candidatus Brocadia with a competitive advantage over other anammox bacteria. Based on the proposed current control strategy (the applied current was calculated to match the influent P loading), precise release of soluble Fe2+ could be achieved by anodic oxidation. Various elemental analysis methods, including the standards, measurements and testing (SMT) protocol, energy dispersive X-ray spectroscopy (eSEM-EDX), X-ray fluorescence spectrometry (XRF) and inductively coupled plasma emission spectroscopy (ICP-OES), jointly indicated that the solid phase of Ele-anammox was primarily Fe-P precipitation, which showed a similar Fe:P ratio with vivianite (Fe3(PO4)2·8H2O, 1.5). X-ray diffraction (XRD) analysis further validated the in-situ crystallization of vivianite, and semi-quantification implied a vivianite content of 85%. Mössbauer spectroscopy showed at least 51.48% ∼ 59.11% of iron was bound in vivianite, while impurity occupation and potential oxidization may impair the purity of P-recovery products, which should be concerned in future practice.

Sequential wet extraction of phosphorus from sewage sludge using alum sludge: Reassessing the aluminium-phosphorus speciation using experimental and simulation approach

Sewage sludge (SS) is a reclaimable phosphorus (P) source for fertilizer production, but it has a high toxic trace element (TE) concentration. Using alkaline leaching of SS, P can be extracted without simultaneous extraction of TEs. However, low P recovery efficiency during alkaline leaching is a major challenge. This study explored alkaline leaching of P from alum sludge (AS)-amended dry SS, with or without acidic pretreatment. The amendment with AS was intended to promote apatite to non-apatite inorganic phosphorus conversion for a higher alkaline P recovery. The highest orthophosphate (ortho-P) alkaline recovery was 74 % for the acid-pretreated SS + AS mix. Amending SS with AS averted the loss of ortho-P during acidic pretreatment by 59 % compared to the reference case (unamended SS). Standards Measurements and Testing (SMT) analysis revealed apatite to non-apatite inorganic phosphorus conversion during acidic pretreatment, especially in the amended SS. This conversion was due to the dissolution of Ca-P and adsorption of dissolved ortho-P on Al(OH)3 during acidic pretreatment. Visual MINTEQ modelling, solid-state NMR (31P, 27Al and 31P-1H CP-HETCOR) and Al 2p XPS data indicated a high abundance of Al(OH)3(s), which enhanced the ortho-P adsorption. There was no formation of AlPO4, possibly because the acid-sludge mixture reached the metastable equilibrium and not the true equilibrium during acidic pretreatment. 31P liquid NMR, SEM, FTIR and XRD provided additional insight into the effects of acidic pretreatment on sludges. Overall, Ca-P to Al-P conversion enhanced alkaline ortho-P recovery by about 12 % compared to the reference case (unamended + non-pretreated). This study demonstrated that P leaching efficiency from SS can be improved (with appropriate process modifications) irrespective of the intrinsic property of SS, thus making alkaline P recovery applicable in many regions globally. Additionally, the chemical co-treatment of SS + AS proposed is a prospective dual waste management strategy.

Functional analysis of extracellular polymeric substances (EPS) during the granulation of aerobic sludge: Relationship among EPS, granulation and nutrients removal

Extracellular polymeric substances (EPS) with high molecular weights, secreted from microorganisms, play a critical functional role in the aerobic granular sludge (AGS). To investigate the level and function of EPS during the granulation of aerobic sludge and in the mature AGS, a sequencing batch reactor (SBR) was operated for 70 days. Aerobic granules with an average diameter of 0.25 mm were obtained with reducing settling time of sludge. Simultaneous removals of COD, nitrogen and phosphorus by the mature AGS exceeded 90, 95 and 95%, respectively. The EPS content increased significantly to above 333 mg/g MLVSS during the initial stage, and after that, it stabilized at about 240 mg/g MLVSS as the mature AGS formed, higher than that of the seed sludge (212 mg/g MLVSS). The increased EPS contents showed a negative correlation with SVI values, while a strong positive relationship with the formation of the AGS. The protein/polysaccharide (PN/PS) ratio in the EPS increased from 1.42 to 4.17, and TP/MLSS increased to about 6%, with the formation of AGS. The proportion of extracellular-P increased with the increase of EPS, and then maintained stable at about 20%, indicating EPS promoted the removal of phosphorus. Furthermore, the results from the Standards, Measurements and Testing (SMT) and X-Ray Diffraction (XRD) showed that phosphorus in the AGS mainly existed in the form of inorganic phosphorus (IP) and the proportion of Ca5(PO4)3(OH) in IP was up to 92%. This investigation demonstrated that EPS had a positive relationship with the sludge granulation and nutrients removal.

Contents and Forms of Phosphorous in the Municipal Sewage Sludge of China

Municipal sludge samples (SS) were collected from 46 cities in China in 2016. The forms in which phosphorus occurred in the SS were evaluated using the Standards, Measurements and Testing (SMT) Program. The results showed that the average contents of total phosphorus (TP), inorganic phosphorus (IP), non-apatite inorganic phosphorus (NAIP), apatite phosphorus (AP), organic phosphorus (OP), and bioavailable phosphorus (NAIP+OP) in the SS were (17.32±5.13), (11.71±4.01), (9.18±3.44), (3.03±2.74), (4.54±4.23), and (13.72±4.36) g·kg-1, respectively. IP was the main form of phosphorus in the SS, accounting for more than 60% of the TP content. NAIP was the main form of IP, accounting for more than 66% of the IP content. There was a highly significant positive correlation between TP and bioavailable phosphorus in the SS (r=0.942, P<0.01), and bioavailable phosphorus accounted for 66.8%-96.1% of the TP content. The contents of phosphorus in the SS and the amounts of phosphorus discharged via SS disposal showed a decreasing trend from the east to the west of China. In 2016, the amount of phosphorus discharged into the environment via SS disposal amounted to 1.04×105 tons, of which 1.95×104 t entered the soil through SS land application, 4.69×104 t entered landfill sites, 1.47×104 t entered building materials, 2.34×104 t ended up in incineration ash, and 4.50 t were directly dumped or discarded. The phosphorus content of the SS of China presented a temporal trend of first increasing and then decreasing.

Alternative approach to the standard, measurements and testing programme used to establish phosphorus fractionation in soils

The fractionation of phosphorus in 9 soils was established according to the standards, measurements and testing (SMT) programme. Five fractions were so defined and phosphorus was analysed by spectrophotometry. In parallel, the phosphorus extracted in each fraction was determined using graphite furnace atomic absorption spectrometry (GFAAS) after validation of this technique using certified reference materials. Phosphorus in soils was named total phosphorus, inorganic and organic phosphorus, apatite and non-apatite inorganic phosphorus, depending on extractants. The use of both analytical techniques revealed differences between the concentration of phosphorus in soluble extracts and highlighted the fact that spectrophotometry was a selective analytical technique. In view of the resource- and time-consuming of the SMT procedure and the results obtained in the present study, an alternative method was proposed to estimate the fractionation of phosphorus in soil in order to precise the potential effects of phosphorus on plant nutrition when plant biomass is produced as part of metal-contaminated soil management.

Microbial Biomass and Community Composition Involved in Cycling of Organic Phosphorus in Sediments of Lake Dianchi, Southwest China

ABSTRACTOrganic phosphorus (Po) was a major fraction of phosphorus (P) in sediments of lakes, and microbes were involved in most of its relevant biogeochemical cycling. Forms and quantification of Po were investigated by sequential fractionation in 18 sediments of Lake Dianchi, Southwest China. Microbial biomass and community structure in these sediments were determined by phospholipid fatty acids (PLFAs). Distribution of Po fractions were in the rank order that humic Po > nucleic acid and polyphosphate > residual P > Ca-Al-Po > Fe-Po > sugar Po > acid soluble Po > H2O-Po. The recoveries of Po and Pi in these detailed sequential fractions including residual P shows that the total contents of Po in sediments of lakes were overestimated by the Standards, Measurements and Testing (SMT) protocol (ignition method). Microbial biomass including Gram-positive bacteria (14.4–20.0%), Gram-negative bacteria (32.7–38.4%), microeukaryotes (14.9–24.4%), aerobic bacteria (43.6–55.8%), anaerobic bacteria (0–2.9%) and type І methanotrophs (17.6–24.4%) were assigned. Microbial mass and their composition were strongly correlated with H2O-Po, Fe-Po, nucleic acid and polyphosphate, and humic Po, though residual P was likely inert for microbes in sediments. The formation and degradation of Po was closely related with microbial activities in sediments. These findings have implications for understanding the role of microbes on cycling of Po and organic matter in sediments of lakes.

Characteristics and Distribution of Phosphorus in Surface Sediments of Limnetic Ecosystem in Eastern China.

Phosphorus (P) is an essential nutrient for aquatic organisms; however, excessive P inflow to limnetic ecosystems can induce eutrophication. P concentrations in the rivers, wetlands and lakes of Eastern China have been amplified by fertilizer and sewage inputs associated with the development of industry and agriculture. Yet, knowledge of the distribution and speciation of P is lacking at the regional scale. We determined the distribution and speciation of P in limnetic ecosystems in Eastern China using Standards, Measurements and Testing (SMT) and phosphorus nuclear magnetic resonance (31P-NMR). The results indicate that P pollution in surface sediments was serious. Inorganic P (Pi) was the primary drive of variation in total P (TP) among different river systems, and Pi accounted for 71% to 90% of TP in surface sediment in Eastern China. Also, the concentrations of TP and Pi varied among watersheds and Pi primarily drove the variation in TP in different watersheds. Sediments less than 10-cm deep served as the main P reservoir. Environmental factors affect the speciation and origin of P. NaOH-Pi, HCl-Pi and organic P (Po) were related to pH accordingly at the regional scale. The physicochemical properties of sediments from different limnetic ecosystems affect the P speciation. HCl-Pi was higher in wetland sediments than in riverine and lake sediments in Eastern China. Conversely, NaOH-Pi was lowest in wetland sediments. Total Po concentration was lower in riverine sediments than in other sediments, but Mono-P was higher, with an average concentration of 48 mg kg−1. Diesters-P was highest in lake sediments. By revealing the regional distribution of TP, Pi and Po, this study will support eutrophication management in Eastern China.

Phosphorus speciation of sediments from lakes of different tropic status in Eastern China.

Information about the chemical composition of phosphorus (P) in sediment is critical for understanding P dynamics and eutrophication in lake ecosystems. Eutrophication as a result of P pollution still persists so we chose to determine the P characteristics of sediments from ten lakes of different trophic status and the relationships between P fractions and environmental factors. The results show that the Standards, Measurements and Testing (SMT) method combined with (31)P-nuclear magnetic resonance ((31)P-NMR) can efficiently show the P characteristics of sediment. Phosphorus concentrations in sediments decreased as the trophic status of the lake improved. Inorganic P (Pi) was the dominant form of total P (TP) in most of the lake sediments and was mainly comprised of HCl-Pi, a stable Pi fraction. Results of (31)P-NMR analysis show that the extracts were dominated by ortho-P (36.4-94.8%) and mono-P (4.0-36.2%), with smaller amounts of diester-P (.6-23.1%), pyro-P (.2-4.4%), and phon-P (.3-.7%). Analysis of the relationships between the P composition and the trophic status of the lakes indicated that the bioavailability of P forms has an influence on the surface water trophic conditions and the health of aquatic ecosystems.

PH dependent phosphorus release from waste activated sludge: contributions of phosphorus speciation

For phosphorus (P) recovery from waste activated sludge (WAS), the most important step is to release P into the solution, which is greatly dependent on the pH of the solution. The contributions of different P speciation to P release amount from WAS as well as P release kinetics were investigated at different pHs, with the Standards Measurements and Testing (SMT) protocol being used for P fractions tests. The results showed that the total P in the solid (TP(s)) release percentages were 36.2% and 12.4% at pH=2.0 and pH=11.0, respectively. P speciation and fractions study made clear that the released P comes mainly from dissolving of inorganic P (IP) under acid condition, but from non-apatite inorganic P (NAIP) and organic P (OP) under alkaline condition. Simulation study using Visual MINTEQ indicated that the P release amount came from the experimental results is unanimous.

Phosphorus Speciation and Vertical Variation in Sediments from Lake Baihua

This paper reports a study on vertical distribution characteristics of phosphorus speciation in samples collected at four sites from Baihua Lake, based on the Standards, Measurements and Testing (SMT) programme. In this study, the total phosphorus (TP) concentrations of these sediments samples varied from 944.86 to 2591.56 mg/kg and inorganic phosphorus (IP) was the main phosphorus fraction. For this heavily contaminated sediment, the IP mainly consisted of the Fe/Al-P. The vertical variation of the phosphorus had a tendency to decrease with the depth at sites JYS and YPZ. Since the concentrations of the TP in sediments were high and the phosphorus release potential and bioavailability were significant, the lake is still facing an ecological risk.

Forms and Bioavailability of Phosphorus in the Suspended Solids of A&lt;sup&gt;2&lt;/sup&gt;/O Process

To investigate the potential bioavailability and mobility of phosphorus (P) in suspended solids, the Standards, Measurements and Testing (SMT) programmers was employed to characterize the distribution of P in suspended solids from different treatment stage of KunmingWWTP.Results showed that: the main form of total phosphorus (TP) in suspended solids was inorganic phosphorus (IP) ,which accounted for 47%~60%.Amongdifferent forms of inorganic phosphorus, Iron-phosphorus was the dominant forms accounted for 82 % of total phosphorus while calcium-phosphorus was only the minor par. Throughout the process, the trend of changes in content is close between total phosphorus and organ phosphorus. Bioavailable phosphorus in suspended solids ranged from 5.903 mg·g-1to7.376mg·g-1 and occupied 89.64%to94.16% of the total phosphorus pool.

Phosphorus Fractionation in Core Sediments from Haihe River Mainstream, China

Sediments from Haihe River mainstream, located in Xingjiaquan, Zhangjiazui, Tianjin, were collected and examined on the basis of P fractionation. SMT (standards, measurements and testing) procedure was adopted to investigate the changes in P concentration with depth in the core sediments collected from the different sampling sites of Haihe River mainstream. The relationships among different P fractions, such as exchangeable P (Ex-P), metal oxide bounded P (NaOH-P), organic matter and grain size, were also discussed. The results indicate that in both sites the rank order of P fractions was HCl-P > Organic P (OP) > NaOH-P > Ex-P in terms of their concentration. The Ex-P represented < 4% of the sediment total P, while the NaOH-P ranged 5–21%. The calcium bound phosphorus (HCl-P) showed considerable contribution (53–80%) to the sediment total P loads. Silt/clay sized sediments exhibited significantly higher concentrations of HCl-P and Ex-P in both sites. However, coarse-sand-sized sediments exhibited significantly higher concentrations of OP in both sites and NaOH-P in Xingjiaquan. Multivariate statistics were performed to identify the factors that influenced the sediment P.

Analytical phosphorus fractionation in sewage sludge and sediment samples

The Standards, Measurements and Testing (SMT) harmonized procedure for phosphorus fractionation in freshwater sediments (SMT protocol), which was developed within the framework of the Standards, Measurements and Testing (SMT) Programme of the European Commission, has been applied to different environmental samples such as sewage sludge, river and marine sediments. The phosphorus contents in the extracts were spectrophotometrically determined; the measurement conditions and the matrix effects were evaluated for each fraction. The partitioning patterns obtained for sewage sludge and sediment samples reveal that the distribution between inorganic and organic phosphorus forms is independent of the matrix composition of the samples. In addition, a higher available phosphorus content was found in sewage sludges due to the higher percentages of labile phosphorus forms, which suggests possible internal phosphorus release. Finally, one simplified pseudototal microwave digestion method was performed for total phosphorus determination which was validated by its application to the reference material BCR-684.

MEASUREMENT OF OPTICAL PROPERTIES OF GREENHOUSE CLADDING MATERIALS: HARMONISATION AND STANDARDISATION

The aim of this European SMT (Standards, Measurements and Testing) project was the development of testing methods for measuring the ageing and the condensation behaviour of plastic films. For the ageing task, the degradation rates of the most important physical, optical and mechanical properties of the film were measured. Amongst others, harmonisation had to be achieved on measuring the optical properties of plastic films. For this purpose identical samples of four different co-polymer films and also special antifog films were measured by the partners. Measured were the direct and diffusive light transmittance, haze, the UV- transmittance and the IR-transmittance (longwave). Harmonisation has been achieved on the terminology, methods, set-up, repetitions, wavelength bands, etc. of the optical properties of greenhouse plastic films.

Shortened screening method for phosphorus fractionation in sediments: A complementary approach to the standards, measurements and testing harmonised protocol

The SMT protocol, a sediment phosphorus fractionation method harmonised and validated in the frame of the standards, measurements and testing (SMT) programme (European Commission), establishes five fractions of phosphorus according to their extractability. The determination of phosphate extracted is carried out spectrophotometrically. This protocol has been applied to 11 sediments of different origin and characteristics and the phosphorus extracted in each fraction was determined not only by UV-Vis spectrophotometry, but also by inductively coupled plasma-atomic emission spectrometry. The use of these two determination techniques allowed the differentiation between phosphorus that was present in the extracts as soluble reactive phosphorus and as total phosphorus. From the comparison of data obtained with both determination techniques a shortened screening method, for a quick evaluation of the magnitude and importance of the fractions given by the SMT protocol, is proposed and validated using two certified reference materials.

Analytical approaches to the determination of phosphorus partitioning patterns in sediments.

Three methods for phosphorus fractionation in sediments based on chemical extractions have been applied to fourteen aquatic sediment samples of different origin and characteristics. Two of the methods used different approaches to obtain the inorganic fractions. The Hieltjes and Lijklema procedure (HL) uses strong acids or bases, whereas the Golterman procedure (G) uses chelating reagents. The third one, the Standards, Measurements and Testing (SMT) protocol, was proposed in the frame of the SMT Programme (European Commission) which aimed to provide harmonisation and the validation of such methodologies. This harmonised procedure was also used for the certification of the extractable phosphorus contents in a sediment certified reference material (CRM BCR 684). Principal component analysis (PCA) was used to group sediments according to their composition and the three extraction methods were applied to the samples including CRM BCR 684. The data obtained show that there is some correlation between the results from the three methods when considering the organic and the residual fractions together. The SMT and the HL methods are the most comparable, whereas the G method, using a different type of reagent, yields different distribution patterns depending on sample composition. In relation to the inorganic phosphorus, the three methods give similar information, although the distribution between non-apatite and apatite fractions can be different.

Characterisation of road sediments near Bordeaux with emphasis on phosphorus.

Road sediments from the region of Bordeaux (France) were analysed for trace metals, hydrocarbons (including Polycyclic Aromatic Hydrocarbons, PAHs) and phosphorus. The aim of the study was to assess their potential risk for the environment. The sediments were collected by means of a sweeper. The particles are mostly sandy clay loam and silty clay loam with 5.6-8.3% CaO. Heavy metal concentrations are generally below the French and Dutch standards for polluted soils, but a few samples have higher concentrations, e.g., 547 mg kg(-1) for Zn, and 222 mg kg(-1) for Pb. PAH concentrations are above the Dutch target value for polluted soils, and could be a threat to the environment: pyrene (2600 microg kg(-1)) and fluoranthene (1400 microg kg(-1)) have the highest concentrations, whereas chrysene (340 microg kg(-1)) has the lowest. Consequently, these sediments must be considered as waste according to the French circular no 2001-39 from 18 June 2001 and cannot be disposed of anywhere. The Standards Measurements and Testing (SMT) protocol for sequential extraction of phosphorus in sediments was used to determine the forms of phosphorus in the samples. Total phosphorus concentration is 620 mg kg(-1) on average, with a maximum of 933 mg kg(-1); organic phosphorus content is low (36 mg kg(-1) on average). The protocol could be slightly amended, especially with regards to organic phosphorus at low concentrations and could then be used for the determination of phosphorus in other materials such as sludge from detention ponds.

Analytical methods for the determination of spirit drinks

This article discusses the results of a project funded by the European Commission (EC) Framework IV Standards Measurements and Testing (SMT) Programme to provide official methods for the determination of spirit drinks. The project involved four main partners and over 60 laboratories in the resulting validation studies that evaluated 11 analytical methods, of which 10 were subsequently validated in the four-year study. The methods tested were determinations for: alcoholic strength; total dry extract; volatile acidity; esters; “congeners”; hydrocyanic acid; anethole; glycyrrhizic acid; chalcones; total sugar; and, egg yolk. The majority of the validated methods have been adopted into, or are under discussion for, European Union (EU) legislation.

Development of a harmonised phosphorus extraction procedure and certification of a sediment reference material.

A harmonised procedure for the determination of the forms of phosphorus in freshwater sediments, developed in the frame of the European Programme, Standards, Measurements and Testing (SMT) has been used for a certification campaign for a reference material. This operationally defined scheme is a good compromise between method performance and reproducibility. Furthermore, the method is rather simple to implement and could be used by water managers on a routine basis. A homogeneous and stable sediment reference material has been prepared and will be available before mid 2001. The so-called SMT protocol, together with the reference material, are useful tools in the field of water management, especially at a time when quality assurance is of paramount importance in laboratory analyses. Knowledge of the bioavailable forms of phosphorus is important not only for analysis of sediments but also for sludge and soils. Therefore, the SMT protocol could be extended to these materials.