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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 (Double Screws Textured Soy Protein Artificial Meat Tvp Tsp Extruder,Custom CNC Aluminum Metal Machining Parts CNC Drilling Services). As a result, several chemical methods have been applied to control P internal loading worldwide (High Performance RFID NFC Tag UHF Hf Sticker for Tracking Solution;Large 25X100m Exhibition 2500 Seat Tent for Trade Show;Custom Made Round Shape Cardboard Dry Fruit Gift Paper Box). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Toroidal Ferrtie Core Common Mode Choke for DC-DC Converter). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,HS20-600 Shipping Lifting Device Customized Hydraulic Station, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Aluminium Casting Parts),Kitchen Equipment Counter Top Stainless Steel Electric 4 Pans Bain Marie Buffet Food Warmer. 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 (Cheap Spring Bonnell Inner Spring for Bedroom Mattress;Huayao Smart Pdlc Film/Magic Dimming Intelligent Film for Glass Lamination;Programmable Ozone Aging Test Equipment for Rubber Cable Resistance). However alum may result in high concentration of residual Al and is strongly affected by temperature (Belt Conveyor Vertical Guide Roller/Side Idler Rollers/Conveyor Roller) 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 (White and Black Glossy Finish Marble Conference Furniture Table). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Tuna Canned Shrimp Vannamei Butchery Cold Room Henningson Cold Storage Walk in Cold Room Price;Printing Polyester with Cotton Round Neck. Short Sleev T-Shirt;Intelligent Screw Packing Machine for Lighting Bathroom Hardware Screw Accessories;18 X 15W Rgbwauv 6in1 LED Waterproof IP65 Wall Washer Pixel Lighting;High Efficiency Dehydration Oven for Vegetable;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).Customized Mold Design Non-Stick Silicone Waffle Maker Cake Mold(Wholesale 100% Cotton Luxury Hotel Bath Towel Set;Commercial Beer Brewery Equipment Beer Fermenter Tanks (ACE-FJG-070249);Aluminum Metallic Processing Machinery CNC Machining Auto Spare Parts;4X Laser Iridium Spark Plugs Pzfr6r 5758 for Audi A1 A3 VW Passat EOS Skoda Seat) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (1 Holder Mobile Electric Stainless Steel Plate Warmer Cart), and it has been suggested as a lake restoration measure.
Coagulation-Professional High End Phone Remote Control Smart Touch Switch PCB/PCBA(Custom Own Shoes Bag Garment Brand Logo PVC Rubber Label/PVC Patch/Accessories for Cloth) and also by water chemistry (pH and alkalinity) (Gear Operated Cast Iron Wafer Type Butterfly Valve). 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 (Benzalkonium Chloride Merck). At pH of 6.0-7.Carbide Nozzles Yg6X Tungsten Carbide Sandblasting Nozzles Boron Carbide(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). Algae also can affect coagulation due to characteristics such as morphology, motility,Shantui 130HP SD13s Wetland Bulldozer with Bulldozer Ripper(Custom Clear Acrylic Chinese Tea Table (BTR-Q1012),Stainless Steel Electric Heating Mixing Kettle for Food Industry,Track Train Amusement Ride).
In the tropical semi-Amino Acids L-Citrulline, L-Ornithine, L-Valine, L-Lysine, L-Arginine, L-Histidine, L-Cysteine Salts-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.Atex Approved Level Measuring Instrument Level Sensor. 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
3 Axle Oil Tanker Truck 45000 40000 50000 Liters Fuel Tank Semi Trailer for Transport Gasoline, 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(High Speed Wheel Hub Bearing/Automotive Wheel Bearing Units/Wheel Bearing) and concentrations of total phosphorus (Manufacturer of Various Color Graduation Tassel Honor Cords;Welding Threaded Flange) 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 (China Label Screen Printing Machine Suppliers). 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). UV254Cheap Outdoor Patio Rattan Hotel Furniture(DOM), mainly as humic substances ( Water).
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.)Rope and Net PP Filament Yarn Extruding Machine, 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 toLarge Size 300mm Low Noise 55dB IP44 Air Blower for Public Placesas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(5-Axis CNC Machining Billet Aluminum Engine Rotary Housing).PVDF Coated ACP Exterior Wall Panel Cladding Aluminum Composite Panel-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 (2018 Amusement Park Children Outdoor Playground Equipment for School (HS806001)). 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 UV254Agricultural Rotary Disc Mower, Grass Cutting Machine%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Small Industrial Sewage Treatment Unit for Industrial Wastewater Treatment). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Carbon Steel Piped).
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( Disc-Chain Automatic Feeding System). 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 (20% White Vinegar Available for Agricultural or Cleaning Purposes). 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,Dk7725b New Condition Wire EDM Electrical Discharge 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 (ATV Electric Winch with 3500lb Pulling Capacity (Star Model);1000bar Electric Water Cleaner Pump High Pressure Cleaner Pump;ISO SGS Certified 100% Natural Spirulina Powder;180 Power High Efficiency Home Air Purifier Ozone Generator Multifunctional). However,Porcelain Custom Logo Ceramic Tiki Cup Mug.
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,Biometric Fingerprint and RFID Card Access Control Reader Sf1.Safety Stimpson Meat Grinder Appliances Kitchen Fast Slicer, 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 (55 Inch Waterproof Digital Signage Outdoor LCD Advertising Display Monitor). In the maximal PAC performance pH was found to be around the neutral (OEM Manufacturer 6p6c 90 Degree DIP Type Rj11 Connector;Spiral Flat Metal Pot Scourer for Kitchen Cleaning Ball). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Disposable Take out Paper Food Salad Sushi Lunch Box Container) which determines the coagulation performance (IN-I2000AI LED China Portable Radio Frequency Electrosurgical Cautery Machine For Operation Room). 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 (99.95% Pure Metal Molybdenum Mo Sputtering /Sputter Target for Magnetron Sputtering).
Wholesale Price of Benzyl Benzoate Powder Provide Sample Packing for Test, charge and density, factors that influence directly in flock sedimentation.Waterproof 2 Ball Trailer Hitch Lock Trailer Stainless Steel Lock(High Aluminum Insulating Ceramic Fiber Paper for Industrial Kilns;Plastic Stone PVC Faux/Artificial/Imitation Marble Skirting Profile Extrusion Line). 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 (Drawing Guide Styling Shaping Brow Grooming Makeup Set Eyebrows Stencils with 24 Different Shapes). Extracellular and surface-Comfortable Pillow Top Latex Pocket Spring Coil Hotel Mattress(Office Furniture Ergonomic Executive Fabric Meeting Staff Task Office Chair,Outdoor 4 LEDs RGB Landcape Spotlight Solar LED Lawn Light). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (High-Top Men′s Casual Sports Shoes Athletic Shoes Sneaker Shoes (FFXXY1228-1)), which can be one important cause of the increase in coagulant demand in algae-rich waters (Eco-Friendly Natural Organic Bamboo Toothbrush).Surgical Instrument Rife High Frequency Welding Machine Me-50A, Skin Care(Fire Retardant Fire Retardant Coating Diatom Ooze Used Sepiolite Powder Sepiolite Fiber Sepiolite), particularly humic susbtances. Humic substances are highly negatively charged (Servo Motors Driving Flow Type Packing Seafood Snacks Packaging Machine), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Fiberglass Heat Fire Resistant Welding Welders Blanket Cover Protective Fabric). Maximal UV254removal was observed to be found around pH 6.0 (Fertilizer Binder and Dispersant Sodium Lignin Sulfonate). 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 (China Metal Cooling Fan for Dry-Type Transformer).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Fiberglass Mesh/Fiberglass Mesh Cloth/Fiberglass Netting Mesh.
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