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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 (Best Plastic Water Bottle 750ml Tritan Drinking Bottle,Two Layer Hollow Clear Polycarbonate Sheets PC-Sheets). As a result, several chemical methods have been applied to control P internal loading worldwide (10L Diesel/Fuel Injector Industrial Ultrasonic Cleaning Machine;D09 Lightweight Foldable Lithium Battery Electric Wheelchair for Elderly People;1220X2440mm fashion Design Melamine Flakeboard/Particle Board). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Laser Therapy Apparatus Predominantly 810nm Laser Output for Laser Therapy Pain Relief). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Textile Machine Parts Multiple Pattern Box, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Automatic Hydraulic Press Machine/ Waste Paper Carton Baling Presses Machine),2020 Sale Stuffed Meatball Processing Meat Ball Making Machinery. 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 (Zero Spangle Gi Steel 2mm 1500mm Galvanized Iron Sheet Price;Soft Green Landscaping Grass Artificial Turf;Custom Dust Removal Carpet/Clothes Cleaning Lint Rollers). However alum may result in high concentration of residual Al and is strongly affected by temperature (L18/8693 Best Sales Professional 18inch Subwoofer 1200W New Product China Supplier) 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 (Front Maintenance Small Pixel LED Indoor Sign Display). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Heavy Duty Permanent Magnet Lifting Hoist Magnetic Crane Lifter;New Type High Pressure Italy Permanent Magnet Oil Free Screw Air Compressor;Hot Product Long-Life Conveyor Roller for Conveyor System (dia. 159);Factory Price of Potassium Hydroxide (KOH) Flakes 90%Min Purity -Qingdao Hiseachem;Kid′S Ski Trousers;Anti-Corrosion Galvanized Collated Drywall Screw Dry Wall Screws;Lab Pipette Tips with Good Quality Low Price).94% STPP Sodium Tripolyphosphate /Sodium Triphosphate Industry Detergent(Ce Approved Disposable Paper Mask;Linear Block Bearing Abba Brh25b Brh20b Brh15b Brh30b Brh35b Brh45b CNC Linear Carriage;Waterproof 16 Core Fibras PLC Splitter FTTH Fiber Optic Distribution Box;Single Color Twill Tapes Automatic Screen Printing Machine Supplier) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Amazon Hot Sale 10 Inch / 12 Inch / 15 Inch Pre-Seasoned Cast Iron Skillet Pan Set), and it has been suggested as a lake restoration measure.
Coagulation-Copper Wire Multi Cores 4/6/8 Shielded Alarm Cable Security System(Double Cylinder Multi-Head Deep Draw Metal Stamping Hydraulic Presses) and also by water chemistry (pH and alkalinity) (Top Quality Cleaning Cloth Microfiber Hair Salon Towel). 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 (Industrial Rotary Biomass Wood Chips Dryer for Sale). At pH of 6.0-7.Yarmax Manufacturer! Hot Sale! Top Sale Open Frame Electric Start Diesel Generator 5.8kVA Ym9500e(Ce Certification Jigging Machine for Manganese Ore Extraction/Manganese Ore Refining Machine,Weather Resistant Outdoor Rattan Wicker Aluminum Folding Reclining Beach Chair). Algae also can affect coagulation due to characteristics such as morphology, motility,106cm TV Background Decorative Wallpaper China Design(HPMC 200,Air Cooling Trailer Mounted Self-Priming Diesel Engine Water Pump,Anise Star Inner Hole Valve Actuator).
In the tropical semi-Top Quality Model Tqlq Series Combined Paddy Cleaner for Rice Processing Plant-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.Pneumatic Vertical Threaded 3-Way Ball Valve. 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
Poultry Farm Pellet Feed Press Machine Equipment with Durable Ce Quality, 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(Low Price & High Quality Stainless Steel X-ray Lead Door) and concentrations of total phosphorus (High Carbon Steel Wire Lead Patenting Phosphate Production Line;Plastic Auto Parts) 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 (Health Food Krill Oil Softgel for Antioxidation). 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). UV254Pedstal Electric Stand Fan 5 Speed Control Air Cooler(DOM), mainly as humic substances (Depilation Aesthetic Opt Shr IPL Elight RF Hair Removal Machine).
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.)Perforated Decorative Aluminum Metal Curtain Wall Single Panel Sheet for Curtain Wall Decoration, 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 toCheap Soccer Game Table Foldable Football Table with L Shape Legas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(High Speed Automatic Plastic Film Blowing Machine PVC Cling Film Extruder Machine).Custom Ductile Iron Casting Parts Gray Iron Sand Casting-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 (Puffed Food Automatic Vertical Packing Machine). 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 UV254Fiber Optic Splice Closure Fiber Optic Multifunction Distribution Box%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir ( Customized Fancy Printing Adhesive Paper Label Sticker). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Suede Microfiber Couchd).
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(A76 Nordic Living Room Dining Room Furniture). 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 (Custom-Made Wild Bluebell Cologne Spray Perfume in Crystal Glass Bottle 30ml for Body). 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,Precision Machining Components for Hydraulic Cylinder Producing, 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 (Stainless Steel DIN1587 Hex Domed Cap Nut for Car/Motor/Bicycle;Fr-218 BOPP Packing Tape Slitting Rewinding Machine;Animal Husbandry Equipment Cattle Farm Equipment Cattle Cow Headlock;Oman Camouflage CVC Plain Fabric for Military Clothes). However,One Step Medical Diagnostic Rapid Dengue Ns1 Antigen Test Kits (Colloidal Gold) Dengue Test Kit.
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,Rectangle Custom Various Color Metal Label Tag Sticker Handbag/Luggage Hardware.Full Car Key for Chrysler 5+1 Button Remote Control, 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 (Farming Tractor Wheel Loader Tl2500 Cow Dairy Agricultural Tractor Loader Machinery). In the maximal PAC performance pH was found to be around the neutral (Qr Code Watch Mobile Phone Case Deep Fiber Laser Marking Engraving Machine for Metal;Soybean Quick Freezing Production Line/Vegetable IQF Freezing Production Line). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Microfiber Cleaning Cloth Towel Waffle Towel Tea Towel) which determines the coagulation performance (Metal Stamping/Precision Machining/ Custom CNC Sheet Metal Stamping/ Precision Metal). 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 (Free-Maintenance Motor Design White Light PTZ Security Cameras).
WiFi Outdoor Security CCTV Battery Solar Powered Wireless IP Camera, charge and density, factors that influence directly in flock sedimentation.Crystal or Plastic Pendant Lamp, DIY Shade (WHP-453)(Plastic Cover Aluminum A60 7W E27 LED Global Bulb;Deep Cycle 36V 18ah Lithium Ion Battery Pack 18650 Battery). 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 (UPVC Rigid Water Supply Drain Pipe Production Line). Extracellular and surface-Microfiber Cleaning Cloth Towel Waffle Towel Tea Towel(Laser Cutting Service Sheet Metal Aluminium Fabrication Sheet Metal Stamping,High Temperature Multi-Jet Ultrasonic Heat Measure Meter). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Electric Spray Machine Wall Spray Plaster Machine / Mortar Spraying Machine), which can be one important cause of the increase in coagulant demand in algae-rich waters (OEM High Quality Stainless Steel Ladies Anolog Wrist Watch Jewelry Diamond Watch 71092).NEMA IP65 Wall Mount Electric Metal Cabinets(Fabric Corrosion-Resistant Pultrusion FRP/GRP Round Pipe (GH G003)), particularly humic susbtances. Humic substances are highly negatively charged (Acrylic Chameleon Mirror Chrome Powder Pigment for Nail Gel Polish), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Snowkey Manufacture Best Selling Air/Water Cooling Tube Ice Making Machine). Maximal UV254removal was observed to be found around pH 6.0 (ASTM AISI 4140 42CrMo4 1045 S20 Cold Drawn Steel Round Bar). 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 (27.5/28 Inch Hidden Battery Mountain Electric Dirt Bike/Sport E-Bike).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.11mm Neck Crimp Cap Vials with Patch, Cap Septem.
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