The hypothesis that the combination of the flocculent polyaluminium chloride (PAC) with the lanthanum-modified bentonite Phoslock® (Flock & Lock) could sink effectively a water bloom of cyanobacteria ...and could shift a turbid, cyanobacteria infested lake to a clear water lake was tested in a controlled laboratory experiment and a whole lake experiment. In the laboratory, a relatively low dose of the flocculent PAC (2.2 and 4.4 mg Al l−1) was insufficient to sediment positively buoyant cyanobacteria (Microcystis aeruginosa). Similarly, the lanthanum modified clay (dosed at 390 mg l−1) was insufficient to sediment the positively buoyant cyanobacteria. However, the combination of PAC and Phoslock® effectively sedimented cyanobacteria flocks. Likewise, a combined treatment of 2 tons PAC and 18 tons Phoslock® in Lake Rauwbraken in April 2008 effectively sedimented a developing cyanobacteria bloom of Aphanizomenon flos-aquae. The average chlorophyll-a concentration in the two years prior to this Flock & Lock treatment was 19.5 (±36.5) μg l−1, while it was as low as 3.7 (±4.5) μg l−1 in the years following the treatment. The combined treatment effectively reduced the amount of total phosphorus (TP) in the water column from on average 169 (±126) μg P l−1 before the application to 14 (±15) μg P l−1 after the treatment. Based on mean summer chlorophyll-a and TP concentrations, the lake was shifted from a eutrophic/hypertrophic state to an oligo/mesotrophic state. From directly after treatment in April 2008 until and including 2013, Lake Rauwbraken remained in an oligo-mesotrophic clear water state with TP reduced to less than 10% of the pre-treatment. This result shows that eutrophication in relatively small, isolated, stratifying lakes can be restored by targeting both water column and sediment P using a combination of flocculent and solid phase P-sorbent.
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•The combination of PAC and Phoslock® (Flock & Lock) precipitates cyanobacteria flocks.•Flock & Lock sedimented a developing cyanobacteria bloom in Lake Rauwbraken.•Flock & Lock reduced TP to less than 10% of the values before Flock & Lock.•Flock & Lock changed the lake from hypereutrophic to oligo-mesotrophic.•Lake Rauwbraken is already more than four years in the oligo-mesotrophic state.
In the present work, we have generated a new second-nearest neighbour modified embedded atom method potential (2NN-MEAM) for the W–P system to investigate the impact of P impurity segregation on the ...strength of symmetric 〈110〉 tilt coincident site lattice grain boundaries (GBs) in tungsten. By incorporating the impurity-induced reduction of the work of separation in the fitting strategy, we have produced a potential that predicts decohesion behaviour as found by ab initio density functional theory (DFT) modelling. Analysis of the GB work of separation and generalized stacking fault energy data derived from DFT and the 2NN-MEAM potential show that P-impurities reduce the resistance to both cleavage and slip. Mode I tensile simulations reveal that the most dominant mode of GB failure is cleavage and that pristine GBs, which are initially ductile, on most accounts change to brittle upon introduction of impurities. Such tendencies are in line with experimentally observed correlations between P-impurity content and reduced ductility.
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•We fit a 2NN-MEAM potential to model P-induced embrittlement of W grain boundaries.•The potential accurately predicts the impact of P on brittle and ductile mechanisms.•Increased impurity coverage is found to promote reduced grain boundary strength.•P-impurities contribute to reduced plasticity and preference for cleavage.
Phoslock® is a lanthanum (La) modified bentonite clay that is being increasingly used as a geo-engineering tool for the control of legacy phosphorus (P) release from lake bed sediments to overlying ...waters. This study investigates the potential for negative ecological impacts from elevated La concentrations associated with the use of Phoslock® across 16 case study lakes. Impact-recovery trajectories associated with total lanthanum (TLa) and filterable La (FLa) concentrations in surface and bottom waters were quantified over a period of up to 60 months following Phoslock® application. Both surface and bottom water TLa and FLa concentrations were <0.001 mg L−1 in all lakes prior to the application of Phoslock®. The effects of Phoslock® application were evident in the post-application maximum TLa and FLa concentrations reported for surface waters between 0.026 mg L−1–2.30 mg L−1 and 0.002 mg L−1 to 0.14 mg L−1, respectively. Results of generalised additive modelling indicated that recovery trajectories for TLa and FLa in surface and bottom waters in lakes were represented by 2nd order decay relationships, with time, and that recovery reached an end-point between 3 and 12 months post-application. Recovery in bottom water was slower (11–12 months) than surface waters (3–8 months), most probably as a result of variation in physicochemical conditions of the receiving waters and associated effects on product settling rates and processes relating to the disturbance of bed sediments. CHEAQS PRO modelling was also undertaken on 11 of the treated lakes in order to predict concentrations of La3+ ions and the potential for negative ecological impacts. This modelling indicated that the concentrations of La3+ ions will be very low (<0.0004 mg L−1) in lakes of moderately low to high alkalinity (>0.8 mEq L−1), but higher (up to 0.12 mg L−1) in lakes characterised by very low alkalinity. The effects of elevated La3+ concentrations following Phoslock® applications in lakes of very low alkalinity requires further evaluation. The implications for the use of Phoslock® in eutrophication management are discussed.
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•Lanthanum (La) concentrations were investigated following Phoslock® treatment in 16 lakes.•La recovery reached an end-point between 3 and 12 months post-application.•La3+ ions were unlikely to cause ecotoxicological effects in moderate-high alkalinity lakes.•Ecological effects of La3+ should be assessed prior to applications in very low alkalinity lakes.
1. Eutrophication constitutes a serious threat to many European lakes and many approaches have been used during the past 20-30 years to improve lake water quality. Results from the various lake ...restoration initiatives are diverse and the long-term effects are not well described. 2. In this study we evaluated data from more than 70 restoration projects conducted mainly in shallow, eutrophic lakes in Denmark and the Netherlands. Special focus was given to the removal of zooplanktivorous and benthivorous fish, by far the most common internal lake measure. 3. In more than half of the biomanipulation projects, Secchi depth increased and chlorophyll a decreased to less than 50% within the first few years. In some of the shallow lakes, total phosphorus and total nitrogen levels decreased considerably, indicating an increased retention or loss by denitrification. The strongest effects seemed to be obtained 4-6 years after the start of fish removal. 4. The long-term effect of restoration initiatives can only be described for a few lakes, but data from biomanipulated lakes indicate a return to a turbid state within 10 years or less in most cases. One of reasons for the lack of long-term effects may be internal phosphorus loading from a mobile pool accumulated in the sediment. 5. Synthesis and applications. Lake restoration, and in particular fish removal in shallow eutrophic lakes, has been widely used in Denmark and the Netherlands, where it has had marked effects on lake water quality in many lakes. Long-term effects (> 8-10 years) are less obvious and a return to turbid conditions is often seen unless fish removal is repeated. Insufficient external loading reduction, internal phosphorus loading and absence of stable submerged macrophyte communities to stabilize the clear-water state are the most probable causes for this relapse to earlier conditions.
Background: Chronic Kidney Disease (CKD) is a pathophysiological process with a diverse etiology, resulting in slow progressive kidney function. Hemodialysis is used as a therapy to replace ...deteriorating renal function. PGK has high mortality and morbidity, because it can cause various complications, one of the complications of PGK is the regulation of mineral settings, especially calcium and phosphate. Methods: The type of research in this study is descriptive quantitative with cross sectional study design. The population in this study were PGK patients undergoing hemodialysis at Anna Medika Bekasi Hospital. Sample selection using simple random sampling technique with condition to fulfill inclusion criteria. Secondary data retrieval (medical record). Results: From 55 samples were 32 patients (58.2%) with hypocalcemia category, 14 patients (25.4%) with normal calcium level, 9 patients (16.4%) with hypercalcemia category, 10 patients (18.2%) with hypophosphatemia category, 4 patients (7.3% ) with normal phosphorus levels and 41 patients (74.5%) by category. Of 32 patients (58.2%) hypocalcemia and 41 (74.5%) hyperphosphatemia which decreased calcium along with a rise in phosphorus by 22 patients (40%). Conclusion: In this study it was found that patients were more likely to have hypocalcemia and hyperphosphatemia. Less than half the patients had decreased levels of calcium along with elevated levels of phosphorus.
This study demonstrates that microalgae can effectively recover all P and N from anaerobically treated black water (toilet wastewater). Thus, enabling the removal of nutrients from the black water ...and the generation of a valuable algae product in one step. Screening experiments with green microalgae and cyanobacteria showed that all tested green microalgae species successfully grew on anaerobically treated black water. In a subsequent controlled experiment in flat-panel photobioreactors, Chlorella sorokiniana was able to remove 100% of the phosphorus and nitrogen from the medium. Phosphorus was depleted within 4 days while nitrogen took 12 days to reach depletion. The phosphorus and nitrogen removal rates during the initial linear growth phase were 17 and 122 mg·L–1·d–1, respectively. After this initial phase, the phosphorus was depleted. The nitrogen removal rate continued to decrease in the second phase, resulting in an overall removal rate of 80 mg·L–1·d–1. The biomass concentration at the end of the experiment was 11.5 g·L–1, with a P content of approximately 1% and a N content of 7.6%. This high algal biomass concentration, together with a relatively short P recovery time, is a promising finding for future post-treatment of black water while gaining valuable algal biomass for further application.
Recovery of phosphorus from wastewater as calcium phosphate could diminish the need for mining of scarce phosphate rock resources. This study introduces a novel approach to phosphorus recovery by ...precipitation of calcium phosphate granules in anaerobic treatment of black water. The granules formed in the Upflow Anaerobic Sludge Blanket (UASB) reactor at lab- and demonstration-scale were analyzed for chemical composition and mineralogy by Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES), Electron microprobe (EMP), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and micro X-ray Diffraction (XRD). The granules had a diameter of 1–2 mm, organic content of 33 wt%, and phosphorus content of 11–13 wt%. Three calcium phosphate phases were identified in the granules: hydroxyapatite, calcium phosphate hydrate and carbonated hydroxyapatite. Without any addition of chemicals, 7 gP/person/year can be recovered with the calcium phosphate granules, representing 2% of the incoming phosphorus in the UASB reactor. As the heavy metal content was lower compared to other phosphorus recovery products, phosphate rock and phosphorus fertilizer, the calcium phosphate granules could be considered as a new phosphorus product.
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•Calcium phosphate granules with 11–13 wt% P were formed in black water UASB reactor.•Precipitated species were calcium phosphate hydrate, HAp and carbonated HAp.•Without any addition of chemicals 7 gP/person/year was recovered with the granules.•Calcium phosphate granules had less heavy metals compared to artificial fertilizers.•Calcium phosphate granules could be considered as a new phosphorus product.
•Microalgae and bacteria treat wastewater without a supply of external oxygen.•All acetate was degraded in the symbiotic biofilm without aeration.•Additional nitrogen removal can be obtained via ...nitrification and denitrification.•HCO3− and CO2 must be available to start up symbiotic microalgal–bacterial biofilms.
Symbiotic microalgal–bacterial biofilms can be very attractive for municipal wastewater treatment. Microalgae remove nitrogen and phosphorus and simultaneously produce the oxygen that is required for the aerobic, heterotrophic degradation of organic pollutants. For the application of these biofilms in new wastewater treatment systems, the engineering aspects need to be investigated to obtain a balanced system where no additional oxygen is required. In this study symbiotic microalgal–bacterial biofilms were grown in flow cells with ammonium and phosphate, and with acetate as biodegradable organic pollutant at a hydraulic retention time of 4.5h. The symbiotic biofilms removed acetate from 323mg/L to 39mg/L without an external oxygen or carbon dioxide supply at a removal rate of 43g COD/m2/d. Ammonium and phosphate could not be completely removed, but removal rates of 3.2g/m2/d and 0.41g/m2/d were obtained, respectively. Further nitrogen removal may be obtained by nitrification and denitrification as the biofilm obtained a considerable heterotrophic denitrification capacity. The symbiotic relationship between microalgae and aerobic heterotrophs was proven by subsequently removing light and acetate. In both cases this resulted in the cessation of the symbiosis and in increasing effluent concentrations of both acetate and the nutrients ammonium and phosphate. Future research should investigate the dimensioning of an up-scaled symbiotic biofilm reactor, and the possibilities to obtain additional nitrogen and phosphorus removal under day–night cycles utilizing real wastewater.
Gelişen ve gelişmekte olan ülkelerde hayvancılık yetiştiriciliği küçük aile işletmeciliğinden ziyade daha fazla kapasiteyle yetiştiricilik yapılan ticari işletmelerde gerçekleştirilmektedir. Marmara ...bölgesinde hayvansal kaynaklı besinlerin talebi karşılayabilmesi için daha çok yoğun üretim yapılan entansif işletmelerde yetiştiricilik yapılmaktadır. Ancak işletmelerde kontrolsüz atık yönetimi, ortaya çıkan büyük miktardaki gübrenin doğru ve etkin kullanılamaması ekosistemde bozulmalara neden olarak çevre kirliliğine ve doğal kaynak deformasyonuna neden olur. Ayrıca insan sağlığını da dolaylı olarak olumsuz etkilemektedir. Tarımsal kaynaklı kirliliğin tespiti ve önlenmesi zor ve zaman alıcı olduğu için en etkili yöntem kirlilik oluşmadan tedbirlerin kaynağında alınmasıdır. Yapılan çalışmanın sonucuna göre; Marmara bölgesinin son on yıllık hayvansal kaynaklı gübreden oluşan kirlilik yükü 25497,5 ton’dur. Bunun %90,6’sı azot kirliliğinden kaynaklanırken % 9,4’üne ise fosfor kirleticisi neden olmuştur. Azot ve fosfor kirliliğine en fazla katkı yapan şehir Balıkesir olurken en az kirlilik Yalova’da oluşmuştur. Kirlilik yükü hayvan sayısıyla doğru orantılı olarak seyir göstermiştir. Büyükbaş hayvanların yayılı kirliliğe en fazla neden olan hayvan türü olduğu ortaya konulurken azot kirliliğine en az kümes hayvanı, fosfor kirliliğine ise en az küçükbaş hayvan neden olmuştur.
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