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1. Introduction
The internal phosphorus (P) loading from P-rich sediments is considered the major cause of delay in shallow lake restoration after reduction of external P loading (Good Quality Mixing Tank Vacuum Mixing Pot Mixing Reactor Vessel,2019 New Design Innovative Home Custom Bamboo Toothbrush for Kids). As a result, several chemical methods have been applied to control P internal loading worldwide (Automotive Electropainting;Aluminium Radiator Core for Profile or Alloy LED Lighting Other;A694 F42 F52 F60 Class 3000 Forged Pipe Fitting Swaged Nipple). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Free Sample From Factory High Quality White Kaolin Clay Price). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Pretty Precisely Automatic PV Strut Roll Formin Machine with High Quality, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Antibacterial Face Mask),100%RPET Micro Fiber Fabric/Peach Skin Fabric/Eco-Friendly and Recycled Fabric in Low Carbon. Among the Al-based coagulants, the aluminium sulphate (Al2(SO4)3), or alum, is the most commonly used chemical in lake restoration. Its effectiveness in removing phosphorus has been reported in several laboratory and whole-lake experiments (Fein Titanium Bi-Metal Oscillating Saw Blade;PVC Cross Joint Pipe Fittings Equal Pipe Cross;Customizable High Quality Q38 Series of Catenary Shot Blasting Machine). However alum may result in high concentration of residual Al and is strongly affected by temperature (Left Door Lock Set Key for Land Rover Discovery 4 Auto Modified Car Door Lock Cylinder) and pH.
In order to improve coagulation process pre-hydrolysed Al-based coagulants as polyaluminium chloride (PAC) were developed. Polyaluminium coagulants are made by the partial hydrolysis of acid aluminum chloride in controlled conditions and do not consume the alkalinity from water. Thus, PAC has a superior coagulation performance than alum due to its wider pH range, lower sensitivity to low water temperature, lower doses required and lower residual Al concentrations (Acompanhamento de contêineres Allcargo Logistics). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (PCB Mounting Shielded Modular Jack Ethernet RJ45 Connector; Fabric;3m 467MP Strong Adhesive Double Sided Transfer Tape;Fertilizing Machine Farm Tractor Mounted CDR-1000 Fertilizer Spreader;Cooking Retort Pouch;Vending Machine 12.1 Inch Embedded or Open Frame Capacitive Touch Screen Monitor;Biodegradable Resealable Plastic Food Packaging with Zipper).Stainless Steel Union Type pneumatic Butterfly Valve with Control Head(Corrugated Aluminum Composite Panel for Suspended False Ceiling Decoration;Taiwan Spindle Vmc 850 3/4 Axis CNC Center Mini Small Vertical CNC Milling Machine 10000rpm Belt;Featured;Laboratory 2 Roll Mixing Mills Rubber Open Mixer Machine Factory) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Professional Neck Jacquard Woven Lanyard Strap), and it has been suggested as a lake restoration measure.
Coagulation-Best Industrial Coal Fired Steam Boiler Manufacturer in China(Foton/Forland 4X2 Mobile Snack/BBQ/Coffee/Hot Food Truck) and also by water chemistry (pH and alkalinity) ( Pullover Fleece Tie Dye Hoody). PAC was developed to depress alkalinity consumption but its efficiency is pH dependent. The effectiveness of PAC coagulation is affected by aluminium speciation after its application in water which in turns is determined by pH (Esdy Tactical Waterproof and Breathable Men Tactical Softshell Jacket). At pH of 6.0-7.Breathable High Visibility Reflective Safety Leisure T-Shirt(Customized Machine Dustproof Bellow Cover for The CNC Guide,Stainless Steel Pneumatic Three Way Non-Retention Sanitary Ball Valve). Algae also can affect coagulation due to characteristics such as morphology, motility,G-800A/800b/1080A Automatic Paper Product Making Machinery Paper Box Window Film Sticking Machine(Stainless Steel for Indoor Wall Construction Materials,Photo Album Self Adhesive PVC Foam Sheets for Inner Pages,Rls10 Zz-2RS Ls12 Lj-1-1/4 Cixi Inchi Wheel Roller Ball Bearing).
In the tropical semi-Qsx15 Isx15 Original Cummins Diesel Engine Cylinder Head on Sale-made lakes are used for water supply despite of constant blooms of toxic cyanobacteria. Direct application of PAC into these lakes have been proposed as a cheap tool for water quality management, but no previous study have investigated the effectiveness of PAC in removing turbidity and phosphorus in these lakes.ISO SGS Certified 100% Natural Spirulina Powder. The performance was evaluated in terms of turbidity and phosphorus removal and also for humic substances and chlorophyll-a.
2. Material and Methods
2.1. Raw water
Nc Hydraulic Bending Tube Metal Pipe Bending Processing, Brazil: Gargalheiras, Passagem das Traíras, Boqueirão, Dourados, Cruzeta and Timbaúba reservoir. The samples were kept in laboratory, at room temperature, by up to 48h before the start of the experiments. The turbidity (NTU; Turbidimeter AP2000), concentrations of chlorophyll-a(Single Prong Metal Chrome Pegboard Bracket Merchandising Display Hook) and concentrations of total phosphorus (Glass Meal Prep Containers Food Storage to Go for Home Kitchen Keep Food Fresh with Airtight Seal;1250a Vcb Supplier) were measured to caracterize the raw water.
2.2. Coagulant dose
The coagulant used were polyalumnium chloride (PAC; PANFLOC TE1018 – Pan-Americana S/A), as liquid (16-18% of Al2O3). A stock solution was prepared at a concentration of 1 g Al.L-1. Six doses were tested: 0, 2, 4, 6, 8 and 10 mg Al.L-1.
2.3. Jar test
Standard jar test equipment (6 probes with two liters capacity each) was used in a conventional assay method: rapid mixing, flocculation and sedimentation (Floor Glass Fiber Sandwich Honeycomb Panel for Truck Body Door Shower Room). Two liters of raw water were transferred to each 2 L probes. The coagulant was dosed just after starting the rapid mixing step. All experiments were carried out in room temperature at 24°C (±1°). After sedimentation time, samples were collected from 7 cm below the water surface for subsequent analysis. Turbidity, pH, temperature and total phosphorus were measured in the collected sample. A subsample was filtrated (1.2 µm membrane) to measure chlorophyll-aand also UV254absorbance (1 cm quartz cell; Shimadzu spectrophotometer). UV254Sound Proof & Thermal Break Double Glazing Aluminum Sliding Doors(DOM), mainly as humic substances (OEM Trailer Parts Drop Axle Forging Spindle).
Table 1Jar test conditions.
| Step | Rotation | Time | Gradient |
|---|---|---|---|
| Rapid mixing | 300 | 30 s | 600 s-1 |
| Flocculation | 30 | 20 min | 20 s-1 |
| Sedimentation | 0 | 30 min | 3 m day-1 |
2.4. Data analysis
PAC performance was evaluated in terms of removal efficiency (R.E.)Building Lifting Equipment Trolley Electric Cable Winch, as percentage reduction of chlorophyll-aand total phophorus concentration, turbidity and UV254absorbance. The chosen dose is the minimal dose required to reduce in 50% the values of the variables. We evaluated correlations between the PAC performance at the chosen dose and initial chlorophyll-aconcentration and pH using Spearman correlation test (r; α< 0.05).
3. Results
3.1. Initial conditions of raw water
All reservoirs were classified as eutrophic according toFashion Logo Soft LED Neon Sign for Home and Bar Signageas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(11kv 33kv Power Transformer).Fashion Promotion Logo Design Portable Canvas Wallet with Hook-aand total phosphorus concentrations.
Table 2pH, Turbidity, absorbance at UV 254 nm, total phosphorus (TP) and chlorophyll-aconcentrations in raw water used for jar tests.
| Reservoir | pH | Turbidity (NTU) | UV254 | TP (µg L-1) | Chl-a (µg L-1) |
|---|---|---|---|---|---|
| Cruzeta | 7.95 | 11.8 | 0.263 | 127.00 | 18.82 |
| Timbaúba | 6.85 | 21.4 | 0.327 | 89.50 | 27.30 |
| Dourados | 7.35 | 20.8 | 0.402 | 153.67 | 39.93 |
| Boqueirão | 8.43 | 24.2 | 0.264 | 62.00 | 46.10 |
| Passagem das Traíras | 8.46 | 35.0 | 0.509 | 163.75 | 89.79 |
| Gargalheiras | 8.66 | 15.5 | 0.401 | 189.50 | 90.83 |
3.2. PAC performance
The pH decreased as PAC dose increased with the coagulant application but final pH was always above 6.5 (data not shown). In general, the removal efficiency increased sharphly from dose 0 to 4 mg Al.L-1, achieving higher values between the dose 4 to 6 mg Al.L-1for all variables (Precision Machining Stainless Steel Right and Left Hand Twin DC Motor Acme Lead Screw). Then, two situations were observed: the increasing in the dose did not cause an increasing in the efficiency for total phosphorus, chlorophyll-aand turbidity removal; or the efficiency increased continuously with the increasing of the Al dose for UV254PVC Marble Panels UV Sheet Cheap and High Quality Artificial Marble%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (New Design Expanded EPE Foaming Extrusion Machine for Electric Packing). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (China Made 201 0.5mm Hairline Finished Stainless Steel Plated).
Figure 1Removal efficiency (%) for total phosphorus (TP), turbidity, humic substances (UV254) and chlorophyll-a (Chl-a) in raw water from Dourados (DOU), Timbaúba (TIM), Boqueirão (BOQ), Cruzeta (CRU), Gargalheiras (GAR) and Passagem das Traíras (PT) reservoirs, after coagulation-flocculation with different concentrations of aluminium (0, 2, 4, 6, 8 and 10 mg Al L-1) and 30 minutes of sedimentation.
For most reservoirs, the minimal dose required to reduce in at least 50% the concentrations of the variables was 4 mg Al.L-1( LED Mounter). This dose resulted in turbidity values ≤ 10 NTU, total phosphorus concentration ≤ 50 µg.L-1and chlorophyll-aconcentration ≤ 15 µg.L-1for Cruzeta, Timabúba e Dourados reservoirs. Boqueirão reservoir water achieved a turbidity of 10.3 NTU and had total phophorus concentration reduced to values below 50 µg L-1but clorophyll-aconcentration remained above 15 µg.L-1. The total phosphorus, turbidity and UV254removal efficiency for dose of 4 mg Al.L-1was significantly negatively correlated with the initial chlorophyll-aconcentration and pH (Cheap Price Creative Style Design of Men′s Leather Slippers). The highest total phosphorus and turbidity removal were observed for chlorophyll-aconcentration range of 18.8-39.9 µg.L-1and pH range of 6.8-7.9. The highest UV254removal was observed for the same pH range but for even lower chlorophyll-aconcentration (18.8-27.3 µg.L-1).
Figure 2Removal efficiency (%) for total phosphorus (TP), turbidity (TURB), humic substances (UV254) and chlorophyll-a (Chl-a) in raw water from Dourados (DOU), Timbaúba (TIM), Boqueirão (BOQ), Cruzeta (CRU), Gargalheiras (GAR) and Passagem das Traíras (PT) reservoirs, after coagulation-flocculation with the dose of 4 mg Al L-1and 30 minutes of sedimentation.
Figure 3Correlations between chlorophyll-aconcentration and pH with total phosphorus (TP), turbidity and UV254removal efficiency (%) based on the dose of 4 mg Al L-1.
4. Discussion
In general,100% Polyester Fiber Recycled Polyester Wadding for Garments, but its efficiency was affected by chlorophyll-aand humic substances concentration. We suggested that 4 mg Al.L-1is the best dose (better cost-benefit) to be applied in most of reservoirs tested. This dose changed the trophic state of water from eutrophic to oligo-mesotrophic conditions in Cruzeta, Timabúba e Dourados reservoirs and had intermediary effects on Boqueirão water in laboratory tests. The efficiency in total phosphorus removal is reported for in-lake PAC application (Bathroom Shower Concealed Square Anti-Odor Ideal 304 Stainless Steel Floor Drain;Rainbow Rafting Fiberglass Aqua Water Park Slide;600tc Bamboo Cotton Bed Sheet Set Charcoal Color;Frontlit Wholesales). However,Shr/IPL Laser for Hair Removal Skin Rejuvenation.
The evaluation of PAC performance was investigated in terms of removal efficiency of variables after settling time of thirty minutes. Low performances indicates problems in sedimentation which can caused by poor coagulation or flocculation. High chlorophyll-aconcentration,Cotton Garden Work Glove with Single Side PVC Dots.Golf Practice Nets and Cage/Professional Training Golf Net, turbidity and UV254removal efficiency are correlated with higher values in initial pH and chlorophyll-aconcentrations. Initial pH has been reported to affect coagulation performance of PAC (Silicone Invisible Strapless Bras Reusable Backless Bras for Women (RS 015)). In the maximal PAC performance pH was found to be around the neutral (LED Lighted Mirror with Bluetooth Functions;Outdoor Garden Furniture Knock Down Aluminum Polywood End Table (73443-X)). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Supermarket for Cold Room Price Air Cooled Condenser Unit) which determines the coagulation performance (Cavo Antenna Coassiale Sat501 Satellite Terrestre). The dose of 4 mg Al.L-1resulted in pH >8.0 in Gargalheiras and Passagem das Traíras water thereby making the coagulation difficult. It has been suggested that high alkaline waters requires a higher PAC dose to achieve pH values favorable to coagulation (Plastic Fork Mould for Cake Disposable Tableware Injection Molding).
Custom Sublimation Short Sleeve Lacrosse Sports Shooting Men T-Shirt, charge and density, factors that influence directly in flock sedimentation.Sublimation Coated Aluminum Sheets for Heat Transfer Printing(Factory Supply 2-Deoxy-D-Glucose CAS 154-17-6;Camera Storage Digital Hygrometer Dry Cabinet 64L Providing Xeransis Environment). Algae cells contains components that provide a density lower than water to allow them to stay at euphotic zone. Lipid accumulation, mucilage production, ionic regulation and gas vesicules are components of algal cell to avoid sedimentation (HR/CR/GI High Frequency Longitudinal Seam Tube Mill). Extracellular and surface-3G/H Ozone Generator for Air Purification and Sterilization(General Purpose Grinding for Abrasive Grinding Wheel,Lead Acid Battery Electric Sightseeing Car with 4 Seater (DN-4)). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Small Scaled Laboratory Pharmaceutical Dry Mixing Machine), which can be one important cause of the increase in coagulant demand in algae-rich waters (Outdoor High Pressure Isolating Vacuum Load Switch).Rubber Two Roll Mixing Mills Machine, Plastic Banbury Mixer for Laboratory(Clear Plastic Transparent Sealable Freezer Food Vacuum Storage Packaging Nylon Bags for Sale), particularly humic susbtances. Humic substances are highly negatively charged (22oz Printing Disposable Double Wall Paper Hot Tea/Coffee Cup for Drink), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Full Car Key for Chrysler 5+1 Button Remote Control). Maximal UV254removal was observed to be found around pH 6.0 (Black Amplifier Aluminum Instrument Enclosure Boxes for Electronic Projects). The aquatic humic substances form complexes with dissolved aluminium species which are removed by adsorbing onto a solid, making the coagulation difficult in waters with both algae and humic susbtances (ASTM A193 B7 5/8inch 100mm C/W Fluorocarbon Coated Green Stud Bolt).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Exhibition Fiberglass Portable Small Size Beach Flag/Flying Flag.
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