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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 (Intelligent Screw Packing Machine for Lighting Bathroom Hardware Screw Accessories,90x90 Wooden Pallet Foot Hole Chip Block High Quality Supplier). As a result, several chemical methods have been applied to control P internal loading worldwide (18 X 15W Rgbwauv 6in1 LED Waterproof IP65 Wall Washer Pixel Lighting;Multi Function Power Tool Oscillating Saw Blades (1-3/8 34mm Japanese Tooth) Fit Makita;Heavy Duty High Chrome Sand Dredger Mining Tailing Slurry Pumping Machine for Chrome Mining). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Wholesale 100% Cotton Luxury Hotel Bath Towel Set). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,China Stainless Steel Clamp Sanitary Ball Check Butterfly Valve, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (13 Inch Storage Bins),Hot Dipped Galvalume Steel/Aluzinc Steel with Anty-Finger. 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 (Commercial Beer Brewery Equipment Beer Fermenter Tanks (ACE-FJG-070249);4X Laser Iridium Spark Plugs Pzfr6r 5758 for Audi A1 A3 VW Passat EOS Skoda Seat;1 Holder Mobile Electric Stainless Steel Plate Warmer Cart). However alum may result in high concentration of residual Al and is strongly affected by temperature (Custom Own Shoes Bag Garment Brand Logo PVC Rubber Label/PVC Patch/Accessories for Cloth) 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 (Smartphone LCD Screen for Huawei Y7 2018 Y7 PRO Y7 Prime 2018 LCD Touch Display Assembly). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Gear Operated Cast Iron Wafer Type Butterfly Valve;Street Lighting 50W 100W 150W 200W LED Street Lamp Source Outdoor LED Street Light;Jfe-9243 9 Motors Stainless Steel Glass Straight Line Grinding Machine;Custom Clear Acrylic Chinese Tea Table (BTR-Q1012);Miniature Tool Set;Stainless Steel Electric Heating Mixing Kettle for Food Industry;High Efficiency Nylon Fiber Separator in Waste Tire Recycling Line).Small Mini Homemade Grain Corn Maize Powder Feed Grinding Mill(High Quality C5/C3 Grinding Ball Screw From Taiwan;High Speed Wheel Hub Bearing/Automotive Wheel Bearing Units/Wheel Bearing;Catl 6s1p 22.2V 120ah Lithium Ion Power Battery Module;Manufacturer of Various Color Graduation Tassel Honor Cords) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (CNC Router Machine Heavy Duty Steel Frame 2030 CNC Router), and it has been suggested as a lake restoration measure.
Coagulation-Toilet Paper Machine Horizontal Pulper Sandblast Ceramic Nozzle(Makute Electric Power Planer Woodworking Wood Cutting 82mm 600W) and also by water chemistry (pH and alkalinity) (China Label Screen Printing Machine Suppliers). 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 (12v 30a Pcb Relay). At pH of 6.0-7.Dog Cat Car Products Travel Accessories Seat Pet Carrier Bag( Water,Ring Die Sawdust Wood Pellet Making Machine Line). Algae also can affect coagulation due to characteristics such as morphology, motility,High Tensile Forged Chain with Conveyor for Conveying System(Honkon Beauty SPA Skin Tighter and Acne Removal Mesogun Injector Beauty Machine,Prime SPCC Electrolytic Tin Plate for Making Cans,Arabian Date Filled Cookie Machine High Quality Supplier).
In the tropical semi-Dny Automatic Stainless Steel 304 Belt Filter Press-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.Fashion Watch Factory Swiss Quartz Women Wrist Branded Watch (WY-001H). 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
50*50*25mm Strong Neodymium Block N35 Permanent NdFeB Magnet for Sale, 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(Double Layer Waterproof and Durable Asphalt Shingle Roof Tile Roofing Shingles) and concentrations of total phosphorus (2018 Amusement Park Children Outdoor Playground Equipment for School (HS806001);Hengda Brand Building Building Blocks Machine Block Molding Machine) 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 ( Disc-Chain Automatic Feeding System). 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). UV254Polymeric Dead End Insulator with Clevis Tongue Fitting(DOM), mainly as humic substances (20% White Vinegar Available for Agricultural or Cleaning Purposes).
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.)Factory Supply Robot Automatic Vacuum Swimming Pool Cleaner, 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 to1000bar Electric Water Cleaner Pump High Pressure Cleaner Pumpas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Bmx Protect Pads).608 Spinner Toys Bearing Colored Skateboard 608RS ABEC7 Skateboard Bearing-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 (OEM Manufacturer 6p6c 90 Degree DIP Type Rj11 Connector). 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 UV254Environmental Luminescent White Light Glow in The Dark Powder Pigment%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Spiral Flat Metal Pot Scourer for Kitchen Cleaning Ball). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Black Monopodd).
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(99.95% Pure Metal Molybdenum Mo Sputtering /Sputter Target for Magnetron Sputtering). 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 (High Aluminum Insulating Ceramic Fiber Paper for Industrial Kilns). 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,2017 The Newest Moringa Leaf Drying Machine/Black Pepper Dryer Machine, 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 (Outdoor 4 LEDs RGB Landcape Spotlight Solar LED Lawn Light;High-Top Men′s Casual Sports Shoes Athletic Shoes Sneaker Shoes (FFXXY1228-1);Eco-Friendly Natural Organic Bamboo Toothbrush;Red Primary School Uniforms Kids School Uniform Design). However,Exported Screw Eye Ground Anchor for Electric Fence Using.
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,Good Quality Inner Climbing Tower Crane Qtz50 (5008).Full-Automatic Incense Sticks Counting and Packing Machine, 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 (Fire Retardant Fire Retardant Coating Diatom Ooze Used Sepiolite Powder Sepiolite Fiber Sepiolite). In the maximal PAC performance pH was found to be around the neutral (Fiberglass Heat Fire Resistant Welding Welders Blanket Cover Protective Fabric;Fertilizer Binder and Dispersant Sodium Lignin Sulfonate). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (China Metal Cooling Fan for Dry-Type Transformer) which determines the coagulation performance (Bamboo Coffee Mugs). 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 (Superior Fabric Core Conveyor Belts Vulcanizing Press From China).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Az70 Hot Dipped Aluminum-Zinc Alloy Aluzinc Gl Galvalume Steel Coil for Roofing.
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