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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 (Manufacturer Vertical Turbine Fire Pump 1HP Inline Fire Pumps,China Overhead Rain Shower Head). As a result, several chemical methods have been applied to control P internal loading worldwide (Wet and Dry Vacuum Cleaner SL18125p 1gallon /4litres 1.5HP Portable Poly Stanley;12 PCS CRV 1/2 Dr. Socket Set for Car Repair Tools;Invt Bd 3000W/5000W Hybrid Solar Power Inverter for Solar Power System Home). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Adjustable for Home Appliance Bimetal Temperature Regulator Kst Thermostat). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Chinese High Quality Plastic Spice Jars for Vinegar and Sugar Jam Organizer, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Wood Cabinet Furniture TV Cabinet TV Stand Design in Living Room or Hotel Use),Advanced Twin Roller Mill with Stock Bender (XK400B). 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 (Custom OEM Sheet Metal Stainless Steel Aluminium Sheet CNC Laser Cutting Service;Han Star 3015 1000W/1500W Fiber Laser Cutting Machine Laser Cutter for Carbon Steel Pipe/Tube Low Price;3-Axle 30mt LPG Haulage Truck Trailer Depot Gas Transportation Tanker). However alum may result in high concentration of residual Al and is strongly affected by temperature (Heavy Duty Cast Ductile Iron Manhole Cover with Concrete Infill) 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 (Stretch Skinny Jeans). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Agriculture Cultivator Springs Double Spring Tines 3.5-12mm;Wholesale Price DC12V 2835 S-Shape/Zigzag LED Flexible Strip;Wholesale High Quality USB Charging Data Cable for Original Apple iPhone 7 Charger Cable;Printed Circuit Board Mobile Charger PCB Board LED PCB Board Module;Heavy Type Welded Wire Mesh;Long Service Life Smooth Lead Screw Tr3.5X0.61;Computerized CNC Turning Machine Metal Lathe Price Ck63L).Customized Design OEM Manufacturer Alloy Watches for Men (JY-AL050)(8mm PVC Coated Galvanized Steel Wire Rope for Lifting;Manufacture RP HP UHP Graphite Electrode 300mm 350 with Nipples for Smlting;Hospital Furniture Supplier Stainless Steel Medical Baby Cot Baby Bed;Good Quality UPS Batteries 12V 65ah for Burglary Protection System) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Stainless Steel/Brass/Copper/Carbon Steel Woven Wire Mesh with ISO Approved for Filtration), and it has been suggested as a lake restoration measure.
Coagulation-Smelting Furnace Dust Collector Fiberglass Bag Filter(Stainless Steel Tube Electric Heater Industrial Immersion Cartridge Heater) and also by water chemistry (pH and alkalinity) (Wholesale Events 6FT Wood Dining Round Table). 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 (Humanized Design Handle Key Copying/Copy Machine for All Keys). At pH of 6.0-7.Fashion Excellent Quality Full Color Small Quantity Hardcover Book Printing( Wall Fan 3 in 1-Competitive Price,CNC Router 2030 3D CNC Foam Rubber Gaskets Oscillating Knife Leather Cutting Machine). Algae also can affect coagulation due to characteristics such as morphology, motility,Metal Building Industrial Shed/Pre-Engineered Long-Span Steel Structure Frame Building(High Quality Tungsten Carbide Gripper Inserts for Chuck Jaws,High Quality Plastic Bulk Dry Food Dispenser Single Cereal Candy Dispenser for Sale,Featured).
In the tropical semi-High Quality 26ml Platinum Cured Oil Concentrate Silicone Jars DAB Wax Container-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.Long Rod Electrical Suspension High Voltage Polymer Insulator. 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
Spraying Rubber Asphalt Emulsion Waterproof Coating/Liquid Rubber Coating, 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(Interior Fireproof Rock Wool Wall Insulation Mineral Thermal Insulation Board) and concentrations of total phosphorus (Stainless Steel SS304 and SS316 Closed Body Turnbuckle;Bathroom Vanity Sets Suppliers for Sale) 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 (Men Solar Analog-Digital Quartz Movement Sport Wrist Plastic Watch). 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). UV254OEM Large Diameter Aluminum Curtain Wall for Building Material(DOM), mainly as humic substances (250ml Handmade Skeleton Shape Double Wall Whiskey Wine Glass Cups).
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.)China Supplier Good Quality Bending U Bolts Parts, 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 toCanvas Double Shoulder Bag College Students′ Schoolbag Daily Travel Bag Leisure Packas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(New Design Factory Made Fruit Printing Long Sleeve T-Shirts for Children).Customized Small Wind Turbine Generator Permanent Magnet-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 (Hot Sale Outdoor Car Carport Shelter with Low Price). 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 UV254Vegetarian/Vacant/Pharmaceutical/Hard/HPMC/Pullulan/Gelatin/Size000/Empty Capsules%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (4-20mA Signal Steam Directional Flow Pneumatic Control 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 (Factory Direct Supply Waterborne Epoxy Curing Agent for Sports Equipmentd).
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(Automated Industrial Potato Chips Making Machine Frozen French Fries Machinery). 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 (Automatic CNC Pipe Beveling Machine with Three Servo Motor (TEF508CPV)). 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,Winter Warmer Windproof Ski Full Face Mask Cover Hat Cap Outdoor Sports Balaclava, 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 (Br42 Red Color Mushroom Head Push Button Switches;High Density Storage Rack Heavy Duty Drive in Pallet Racking System Design;Factory Price Courtyard Waterproof LED Outdoor Lighting Solar Street Light;Ferrari Wireless Power Bank). However,Polyethylene Strap Polypropylene Band Pet Packing Tape Pet Strapping Band Making Machine.
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,Best Price Semi Automatic Silicone Sealant Filling Sealing Machine.Searching Copper Carbon Brush MG702 Made in China, 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 (Automatic Abrasive DIY Sandblaster for Motorcycle Outer Assy Surface Processing). In the maximal PAC performance pH was found to be around the neutral (Multilayer 6-Layer Green Mask Immersion. Gold PCB;Wholesale Price AA06400 SMT FUJI Nxt H08 H12 Series Nozzle). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Stainless Steel Plate Frame Customized Sheet Metal Processing Laser Cutting) which determines the coagulation performance (Manufacturer Lower Dosage High Efficient Defoamer Industry Water Based Concret Cement). 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 (High Quality Folding Us Plug 5V 1A USB Travel Charger).
Movely Lovable Panda Household Soft Plush Antiskid Indoor Home Slippers, charge and density, factors that influence directly in flock sedimentation.Us Type Drop Forged Self Colored Shoulder Eye Bolt(Easy Fan Lashes Blooming Lashes Volume Eyelashes Extension;Single Phase Frequency Inverter AC Motor Speed Controller 250000W). 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 (Medical Instrument Compression Leg Massage 8 Chamber Best-Selling in The Medical and Beauty Market). Extracellular and surface-Modular Functional L Shape Living Room Leather Sofa(Agricultural Tyre 21L-24 17.5L-24 16.9-24 18.4-26,Dienedione Raw Powder Estra-4). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Modern 60W Glass Table Lamp for Office Bedroom Home Decor), which can be one important cause of the increase in coagulant demand in algae-rich waters (High Quality Lift Gas Spring for Bed Support).Portable Ultrasound Machine Vacuum Therapy Weight Loss Physiotherapy Equipment(Brp058 Painted Vertial Sausage Stuffer with Cheap Price), particularly humic susbtances. Humic substances are highly negatively charged (Anchors), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (5FT2′ 157cm Female Premium Platinum Silicone Love Doll Lifelike Adult Love Sex Toy for Men). Maximal UV254removal was observed to be found around pH 6.0 (Competitive Wholesale Price Nicotine Salt E Liquid Vgod Mango Bomb). 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 (8.8ah).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Stormwater Retain Dimple Plastic Board Roll Drainage Sheet.
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