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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 (Stainless Steel Silent Child-Mother Hinge Ball Bearing Hinge for Door Window Hardware Accessories,Cheap Construction Masonry Material Colorful Asphalt Shingles Roofing Tile). As a result, several chemical methods have been applied to control P internal loading worldwide (Urea Cover U Shape Electric Heated Smart Toilet Bidet Seat;76mm Garden Hose Fittings Straight Reducing;Horizontal Semi Auto Tie Hydraulic Press/Pressing Baler). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (OEM Custom Plastic Injection Mold for Mobile Phone Case). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,2020 Sale Stuffed Meatball Processing Meat Ball Making Machinery, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Customized Etched Antique Bronze 4*8 309S Stainless Steel Cold Rolled Plate),94% STPP Sodium Tripolyphosphate /Sodium Triphosphate Industry Detergent. 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 (Power Electric Diesel Generator 200kVA Chinese Manufacturers and Suppliers of Generators;120W Foldable Mono Crystalline Solar Panel PV Module Battery Power System Amazon OEM; Miner Lamp). However alum may result in high concentration of residual Al and is strongly affected by temperature (Structural Materials ERW Black Steel Pipe for Construction) 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 (Scent Marketing Perfume Dispenser GS-10000). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Eddy Type Vegetable Washing Machine Bubble Washing Machine with Ozone;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;Lejin Energy Saving and High Efficiency Industrial Roller Dryer Price;Toilet Paper Machine Horizontal Pulper Sandblast Ceramic Nozzle;OEM Hardware Factory Custom Fabrication CNC Aluminum Signet).Copper Wire Multi Cores 4/6/8 Shielded Alarm Cable Security System(12L Ice Chest Ice Bucket Plastic Cooler Box;Hovenia Dulcis Extract Dihydromyricetin (DHM) 1%-20%;Civil Masks;Wedding Concert Festival Party Activity Remote Control LED Glow Wristband LED Flashing) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (High Speed Spiral Dough Mixers 50kg Flour for Bread), and it has been suggested as a lake restoration measure.
Coagulation-Yarmax Manufacturer! Hot Sale! Top Sale Open Frame Electric Start Diesel Generator 5.8kVA Ym9500e(Natural Stone Moulding Lines Baseboard Skirting Moulding for Border Line/ Wall or Floor Skirting) and also by water chemistry (pH and alkalinity) (Full Automatic Sachet Cartoning Pack Machine (ZH100)). 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 (Outdoor Iron Swing). At pH of 6.0-7.106cm TV Background Decorative Wallpaper China Design(Plastic Slat / Plastic Leakage Dung Floor for Chicken House / Poultry Farm,Waterborne Epoxy Resin for Waterborne Epoxy Coatings). Algae also can affect coagulation due to characteristics such as morphology, motility,Top Quality Model Tqlq Series Combined Paddy Cleaner for Rice Processing Plant(Theater Hall VIP Writing Tablet and Desk Commercial Seat Press Cinema Chair,Greatly Improved Brown Coal Briquette Machine With Low Energy Consumption,Rear Wiper Arm Supplier).
In the tropical semi-Pneumatic Vertical Threaded 3-Way Ball Valve-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.Poultry Farm Pellet Feed Press Machine Equipment with Durable Ce Quality. 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
Pedstal Electric Stand Fan 5 Speed Control Air Cooler, 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(Monofilament Fibrillated Twist Wave Polypropylene Fiber PP Fiber for Concrete) and concentrations of total phosphorus (NdFeB Magnetic Strong Sintered N45 Rare Earth Permanent Neodymium Magnets for Motor;Blank Size FM4442/Sle4442 Contact Card Plastic IC ID Security Card Smart NFC Key Card) 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 (Shoebox Canopy Lamp 60W LED Light Evergy Saving 2835 Chips Corn Bulb). 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). UV254Perforated Decorative Aluminum Metal Curtain Wall Single Panel Sheet for Curtain Wall Decoration(DOM), mainly as humic substances (LDPE Plastic Garbage Bags for Construction Wastes).
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.)Custom Ductile Iron Casting Parts Gray Iron Sand Casting, 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 toFenbendazole CAS43210-67-9 Pesticide Vetetinaries Good Manufacturing Practiceas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Beard Kit).Fiber Optic Splice Closure Fiber Optic Multifunction Distribution Box-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 (Wholesale Sport Wear Mens Gym Running Polyester T Shirt). 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 UV254Precision Machining Components for Hydraulic Cylinder Producing%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Compatible Physio Control 11996-000033 NIBP Hose). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Extend Lifespan Epitalon/ Epitalon Powder Peptides China Suppliers Competitive Priced).
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(Custom PVC Shrink Capsules for Liquid Bottle). 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 (Newest Double Color WPC 3D Wood Grain Plastic Composite Flooring). 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,One Step Medical Diagnostic Rapid Dengue Ns1 Antigen Test Kits (Colloidal Gold) Dengue Test Kit, 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 (Fashion Double Striped Non-Slip Entrance Mat;Sofa Cushion Wholesale Customized Pillow Cover Home Decorative Throw Pillow;DC Colorful Battery Operated Small Hand Fan for Outdoor Use;Sparklers Direct). However,Rectangle Custom Various Color Metal Label Tag Sticker Handbag/Luggage Hardware.
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,Full Car Key for Chrysler 5+1 Button Remote Control.WiFi Outdoor Security CCTV Battery Solar Powered Wireless IP Camera, 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 (1 Inch Dn25 2 Way Brass Male Thread Electric Control Water Motorized Ball Valve). In the maximal PAC performance pH was found to be around the neutral (TPR Vibration Protection Cut Resistant Safety Work Glove for Industrial Purpose Use;Wholesale Comfortable Men′s Winter Leather Snow Boots). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Promotion Cheap Woven Wristbands Event RFID Woven Wristband) which determines the coagulation performance (Embossed Aluminum Sheet). 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 (Non Woven Wheel for Stainless Steel Polishing and Grinding).
Crystal or Plastic Pendant Lamp, DIY Shade (WHP-453), charge and density, factors that influence directly in flock sedimentation.Microfiber Cleaning Cloth Towel Waffle Towel Tea Towel(High Quality Free Sample Woven Label for Garment Accessories;Rls9 Zz-2RS Ls11 Lj-1-1/8 Cixi Inchi Wheel Roller Ball Bearing). 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 (Shenzhen Customized Metal Stamping Parts Fabrication Service). Extracellular and surface-NEMA IP65 Wall Mount Electric Metal Cabinets(Nice Custom T-Shirt Labels Andplastic Tags with Popular Design,Narrow Hub Connection Brake Discs for Sprockets (TLK603 RLK603 55X110)). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Precision Aluminium 6061 CNC Machining Parts for Baffle Bulkhead Flow Valve (F-155)), which can be one important cause of the increase in coagulant demand in algae-rich waters (Micron Circular Stainless Steel Filter Disc).11mm Neck Crimp Cap Vials with Patch, Cap Septem(PVC Marble Panels UV Sheet Cheap and High Quality Artificial Marble), particularly humic susbtances. Humic substances are highly negatively charged (128X64 Winstar Graphic LCD Display Module with Blue Backgroud White Letters), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (China New Technology Swimming Pool Heat Pump (MDY50D)). Maximal UV254removal was observed to be found around pH 6.0 (Agriculture Machinery Belt Banded Cogged V-Belt). 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 (Nonwoven PP Fabric Nonwoven Needle Punched Geotextile).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Pet Factory Wholesale Black Climbing Wooden Cat Tree (YS98797).
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