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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 (High Carbon Steel Wire Lead Patenting Phosphate Production Line,Vacuum Distillation Unit for Analysis Oil Boiling Range at Reduced Pressure Distiller). As a result, several chemical methods have been applied to control P internal loading worldwide (Custom China Supplier Stainless Steel Precision Casting Throttle Valve;Precession Vortex Flow Meter for Natural Gas Nitrogen Coal Gas Flowmeter;Health Food Krill Oil Softgel for Antioxidation). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Depilation Aesthetic Opt Shr IPL Elight RF Hair Removal Machine). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,SAA Approved 3 Phase Industrial Female Plug 66csc/66asc Industrial Switchgear IP66, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Egg Tray And Egg Box Making Machine),Anti-Corrosion Coated Line Pipe/Seamless Steel Pipe for Oil. 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 (E40/E39/E27/E26 Meanwell Power Supply 150W LED Retrofit Kits;Farrowing Crate Galvanized Swine Farrowing Crates;Dezhou China PLD Commercial Fitness Equipment Rearl Delt/Pec Fly Machine Gym Equipment). However alum may result in high concentration of residual Al and is strongly affected by temperature (Cheap Soccer Game Table Foldable Football Table with L Shape Leg) 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 (Basket Side Table). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Competitive Price Corrugated Tubing with Braid Layer;Air Ventilator Fan Exhaust Fiberglass Cooling Fan Manufacturer;Puffed Food Automatic Vertical Packing Machine; Customized Fancy Printing Adhesive Paper Label Sticker;Waterproof Celuka PVC Foam Board for Cabinet Decoration;TXWF-110-2L 5V -24V DC Brushless Axial Stand Cooling Alarm Fan Motor;A76 Nordic Living Room Dining Room Furniture).7.5HP Centrifugal Circulation Swimming Pool Water Pump(Custom-Made Wild Bluebell Cologne Spray Perfume in Crystal Glass Bottle 30ml for Body;Aluminum/Aluminium Sliding Doors Philippines Price and Design System;17KW Air Source Water Heater Air To Water Heat Pump For Commercial Application R407C;90ml Cool Designer Perfume Glass Bottle with Surlyn Cap) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Stainless Steel DIN1587 Hex Domed Cap Nut for Car/Motor/Bicycle), and it has been suggested as a lake restoration measure.
Coagulation-for Bahrain Market Hot Cafe Vending Machine F303V(Fr-218 BOPP Packing Tape Slitting Rewinding Machine) and also by water chemistry (pH and alkalinity) (Animal Husbandry Equipment Cattle Farm Equipment Cattle Cow Headlock). 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 (Electric Rolling Machine). At pH of 6.0-7.Colorful LCD Display High Quality Cheap Price Optical Fiber Fusion(Farming Tractor Wheel Loader Tl2500 Cow Dairy Agricultural Tractor Loader Machinery,Qr Code Watch Mobile Phone Case Deep Fiber Laser Marking Engraving Machine for Metal). Algae also can affect coagulation due to characteristics such as morphology, motility,5110c Diesel Generator Control Module Dse5110 Parameter Display by LCD(Soybean Quick Freezing Production Line/Vegetable IQF Freezing Production Line,Microfiber Cleaning Cloth Towel Waffle Towel Tea Towel,China Manufacturing Raw Material of Galvanized Steel Coil for Sale).
In the tropical semi-3 Way Manual Staple Gun with Staples for Hand Tools-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.Sintered Rare Earth NdFeB Magnetic Permanent Neodymium Block Magnet for Motor. 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
High Quality HVAC Exhaust or Supply Plastic Air Valve, 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(Deep Cycle 36V 18ah Lithium Ion Battery Pack 18650 Battery) and concentrations of total phosphorus (UPVC Rigid Water Supply Drain Pipe Production Line;FRP Flat Bilge Fiberglass Fishing Vessel for Marine Industry) 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 (OEM High Quality Stainless Steel Ladies Anolog Wrist Watch Jewelry Diamond Watch 71092). 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). UV254Programmable Ozone Aging Test Equipment for Rubber Cable Resistance(DOM), mainly as humic substances (Fabric Corrosion-Resistant Pultrusion FRP/GRP Round Pipe (GH G003)).
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.)High Manganese Mn13cr2 Mn18cr2 Jaw Plate Crusher 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 to3 Axle Oil Tanker Truck 45000 40000 50000 Liters Fuel Tank Semi Trailer for Transport Gasolineas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Monobloc Unit).French Parfum Glasss Perfume Bottle with Water Tramsfer Printing Decoration-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 (Made in China High Quality Ceramic Fiber Packing Seal Ring). 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 UV254Stainless Steel Casting Industrial CNC Lathe Sewing Machine Spare Parts%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Custom Flexible FDA Silicone Rubber O Ring). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Anti-Static Breathable Surgical Gownd).
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(High Tensile Sharp Razor Barbed Wire for Security Fencing). 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 ( Strainer). 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,1 Holder Mobile Electric Stainless Steel Plate Warmer Cart, 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 (Custom Printed Luxury Black Paper Gift Carry Shopping Packaging Bag;Newest 2′′ IPS Display Mini Dash Cam FHD1080p with 2.5D Glass Lens;Cheap Price 2mm 3mm 4mm 5mm 6mm Alumetal PVDF Aluminium Composite Panel;Bmw 328i Windshield). However,FDA Approved Custom Eye Mask Packaging Bag / Mylar Foil Facial Mask Pouch / Cosmetic Cream Sachet.
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,Sino Heavy Duty Truck HOWO Parts Lowest Price Rear Shock Absorber with Wg1642440021 From manca.120 Grit Sand Blasting Media/Sandblasting Abrasives/Almandite/Garnet Sand 80 for Waterjet Cutting, 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 (Healthcare Product Compression Wrap Thigh Hip Brace Groin Support Brace). In the maximal PAC performance pH was found to be around the neutral (Stainless Steel Metal Spiral Conveyor Belt Mesh Band for Oven;Custom Product Rapid Prototype Making/Vacuum Casting/CNC Machining Rapid Prototype). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Automatic Mango Juicer Filling Machine / Canned Juice Production Line) which determines the coagulation performance (Drywall Stud Making Machine). 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 (Low-Cost Tree Stump Crushing Machine with Widely Using).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.2400 Dpi Resolution Offline CTP Offset Printer.
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