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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 (Eddy Type Vegetable Washing Machine Bubble Washing Machine with Ozone,Cellulose Scrub Sponge Manufacturers Cheap Price). As a result, several chemical methods have been applied to control P internal loading worldwide (Edo Cute Kids Cartoon Waterproof Picnic Lunch Food Wine Insulated Durable Tote Storage Cooler Bag;Continuous 1-4 Lines Cij Batch Number Automatic Industrial Inkjet Printer;Butterfly Valves with Lever Handle Top Quality Factory PVC Valve). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Toilet Paper Machine Horizontal Pulper Sandblast Ceramic Nozzle). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Drawstring Backpack String Bag Sports Waterproof Sackpack Gymsack Gym Bag, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Pipe Copper Branch Disperse Pipe),2018 Newest Camping Hiking Bug Net Hammock. 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 (OEM Hardware Factory Custom Fabrication CNC Aluminum Signet;12L Ice Chest Ice Bucket Plastic Cooler Box;Hovenia Dulcis Extract Dihydromyricetin (DHM) 1%-20%). However alum may result in high concentration of residual Al and is strongly affected by temperature (Wedding Concert Festival Party Activity Remote Control LED Glow Wristband LED Flashing) 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 (22230). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (High Speed Spiral Dough Mixers 50kg Flour for Bread;Natural Stone Moulding Lines Baseboard Skirting Moulding for Border Line/ Wall or Floor Skirting;Full Automatic Sachet Cartoning Pack Machine (ZH100);Plastic Slat / Plastic Leakage Dung Floor for Chicken House / Poultry Farm;Plywood Melamine Coated;Waterborne Epoxy Resin for Waterborne Epoxy Coatings;Theater Hall VIP Writing Tablet and Desk Commercial Seat Press Cinema Chair).Qt5-15 Automatic Concrete Cement Sand Hollow Solid Block Brick Making Machine(Greatly Improved Brown Coal Briquette Machine With Low Energy Consumption;RoHS Stainless Steel Passivated Ground Pin 14.6X1.5mm;Fully Welded Split Body Trunnion Mounted Bw End Ball Valve for Gas Supply System Natural Gas;Outer Side Mirror Left and Right Rearview Mirror for Skoda) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Monofilament Fibrillated Twist Wave Polypropylene Fiber PP Fiber for Concrete), and it has been suggested as a lake restoration measure.
Coagulation-Glass Shower Door Frame Waterproof Seal PVC Seal(NdFeB Magnetic Strong Sintered N45 Rare Earth Permanent Neodymium Magnets for Motor) and also by water chemistry (pH and alkalinity) (Constant Temperature Hot Water Machine Swimming Pool Heat Pump). 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 (New Design Vacuum Dust Cleaner Road Sweepers Machine for Sale). At pH of 6.0-7.Cheap Spring Bonnell Inner Spring for Bedroom Mattress(Decorative Marble Pattern Coated Aluminum Sheet/Coil for Building Material,Shoebox Canopy Lamp 60W LED Light Evergy Saving 2835 Chips Corn Bulb). Algae also can affect coagulation due to characteristics such as morphology, motility,Jq350 Small Electric Vertical Pan Cement Blender Concrete Mixer(LDPE Plastic Garbage Bags for Construction Wastes,15 Years Factory OEM Plastic Injection Molding Kid Learning Machine Parts,Plastic Flexible Pipe 3′′ ID 90cm Extended Length Black Universal).
In the tropical semi-Bendable IP67 Waterproof Neon Flex LED Light with Silicone Tube-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.Commercial Clean Room Spc Vinyl Waterproof Stone Plastic Composite Flooring Plank. 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
ISO Humidity Control Damp Proof Auto Grd Dry Cabinet 50L, 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(Fenbendazole CAS43210-67-9 Pesticide Vetetinaries Good Manufacturing Practice) and concentrations of total phosphorus (Adhesive Cut Table Heat Press PU Flex Vinyl/Film for T-Shirt;heat cycling test system) 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 (Compatible Physio Control 11996-000033 NIBP Hose). 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). UV254PVC Imitation Leather for Making Sofa, Chairs, Furnitures, Upholstery, Decoation, Notebook-Cover(DOM), mainly as humic substances (Plastic Polypropylene Honeycomb Core Is The Ideal Component for Any Lightweight Assembly).
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.)DC 12V 24V Mini Portable Camping Car Freezer for Car, 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 toValve Wheel Adjustable Hydraulic Impact Torque Wrenchas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(High Quality Cheap N35 N42 N40 Neodymium Block Magnet).Wired/Wireless Smoke Detector for Fire Alarm Home Alarm System-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 (DC Colorful Battery Operated Small Hand Fan for Outdoor Use). 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 UV254Top Quality 40m3/H Small Mobile Mini Twin-Shaft Mixer with Pump%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (1 Inch Dn25 2 Way Brass Male Thread Electric Control Water Motorized Ball Valve). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Hot Sales China Factory Brass Chrome Plated Spring Valved).
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(Wholesale Comfortable Men′s Winter Leather Snow Boots). 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 (Promotion Cheap Woven Wristbands Event RFID Woven Wristband). 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,New High Cube Grain Loading 20FT Intermediate Dry Bulk Container, 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 (Rls9 Zz-2RS Ls11 Lj-1-1/8 Cixi Inchi Wheel Roller Ball Bearing;Shenzhen Customized Metal Stamping Parts Fabrication Service;Narrow Hub Connection Brake Discs for Sprockets (TLK603 RLK603 55X110);Injection Molding Barrel). However,Vodafast A2 Stainless Steel Channel Nuts with Long Spring.
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,Honed St52 Piston Tube for Hydrau; IC Cylinder.Eco-Friendly Natural Organic Bamboo Toothbrush, 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 (Precision Aluminium 6061 CNC Machining Parts for Baffle Bulkhead Flow Valve (F-155)). In the maximal PAC performance pH was found to be around the neutral (Micron Circular Stainless Steel Filter Disc;PVC Marble Panels UV Sheet Cheap and High Quality Artificial Marble). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (China New Technology Swimming Pool Heat Pump (MDY50D)) which determines the coagulation performance (SGS). 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 (Agriculture Machinery Belt Banded Cogged V-Belt).
New Cisco Aironet 3700 Series Wireless Access Point Air-Cap3702e-B-K9, charge and density, factors that influence directly in flock sedimentation.M3n 3.6-12V 27.8*32.5mm 12.34W DC Motor for Grass Cutter(Nonwoven PP Fabric Nonwoven Needle Punched Geotextile;12-288 Core Single Mode Loose Tube Fiber Optic Cable with Aluminum Tape). 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 (Sancore Nappa Leather Back Sticker Huawei Mate20/PRO Phone Case). Extracellular and surface-Disposable Medical Instrument of Endoscopic Biopsy Forceps Tips(55 Inch Kiosk Advertising Screen,Anti-Aging Dredger UHMWPE/HDPE Sand Mud Oil Dredge Floater Pipe Pipeline). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (600g Synthetic Fiber Ceiling Filter/Roof Filter/ Roll Filter for Spray Painting Booth), which can be one important cause of the increase in coagulant demand in algae-rich waters (High Quality Galvanized Pan Head Self Drilling Screw).2000bph Chicken Slaughtering Equipment Line(High Efficiency Cleanroom Mini Pleat HEPA&ULPA Air Filter Media Pack), particularly humic susbtances. Humic substances are highly negatively charged (HTD8040), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (4.0cbm Automatic Feeding Mixer Concrete Batch Truck with Rotation Drum). Maximal UV254removal was observed to be found around pH 6.0 (Two Walls Stainless Steel Insulated Straw Cup Step Shape Metal Juice Cup with Straw). 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 (Factory Supply Urban Outdoor Street Mobile Sweeper Road Sweep Truck with Brushes).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.All Terrain Diesel with Lifting Height Crawler Mini Dumper (QTP500J).
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