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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 (Ce Marked Nylon Disposable Cleaning Brush for Endoscope Channel,High Clarity Corrugated Polycarbonate Sheet Solid Sheet Hollow Sheet for Decoration). As a result, several chemical methods have been applied to control P internal loading worldwide (Diesel Engine Parts Cylinder Head for Mitsubishi 4D30A/4D31 Me999863;Gi Galvanized Iron Sheet Hot Dipped Galvanized Steel Sheet Galvanized Sheet Metal Plates;Commercial Promotion White Inflatable Party Tent for Exhibition). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Mobile Fast Food Vending Hot Dog Concession Trailer/Cart Pizza Truck/Mobile Food Car). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Porcelain Tea Cup and Saucer Sets Wholesale Tableware Ceramic, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (SSR-15da Single Phase DC to AC Mager Solid State Relay),Customized Disposable BBQ Bamboo Round Stick and Skewers.. 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 Diecasting Fashion Zinc Alloy Enamel Metal Name Tag;Ykk Series of Air-Cooled 6kv Medium-Sized High-Voltage Three-Phase Asynchronous Motor;Frontlit PVC Flex Banner for Outdoor Advertising). However alum may result in high concentration of residual Al and is strongly affected by temperature (Cc+ Hot Sale Atc Spindle with Gmn Bearing Air Cooling Spindle Same as Italy Hsd) 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 (LSR Silicone Rubber for Pacifiers Nipples Bottles Soothers). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (60 Ton Track Material Handling Excavator for Sale;Industrial Aluminum Extrusion Profiles 6063 T5;Kinkai Meat Heat Pump Dryer Machine/ Drying Oven;ODM OEM Custom Stainless Steel Sheet Metal Fabrication Service Product Sheet Metal Works;High Temperature Resistance Extrude Silicone Rubber Sealing Strips for Oven;Dn200-8inch-EPDM-Rubber Seat Double-Flanged 24V/DC Electric Rotary Actuator PVC/Plastic Butterfly Valve;Patened Design Large Mich Indoor Trampoline Park for Kids).Ceramic Coil 0.5ml Cartridges Disposable Cbd Vape Pen(China Supply High Quality MIFARE® DESFire® EV1 2K/4K/8K RFID White PVC Card;TUV Standard China Jump Park Free Jumping Bounce Bed Trampoline Park for Kids;Laminate Mdf;Hot Sale Glass Manual Salt Grinder Pepper Mills/Spice Jars) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes ( Portable Home Dehumidifier for Whole House), and it has been suggested as a lake restoration measure.
Coagulation-Sesame Almond Cashew Nut Peanut Butter Making Processing Machine(LED Display Fixed Co Gas Monitor Toxic Gases Analyzing) and also by water chemistry (pH and alkalinity) (Rare Earth Metal Material Cerium Target for Magnetron Sputtering System). 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 (Plastic Zip Lock Stand up Biodegradable Standup Pouch Factory From China). At pH of 6.0-7.Big Engine, Large Output Forestry Application Biomass Wood Chipper(Fiber Laser Marking Machine with Jpt Mopa 120W Laser Source for Cutting Thin Metal,Disposable Rotatable Endoscopic Grasping Net Loop). Algae also can affect coagulation due to characteristics such as morphology, motility,LED Lighted Mirror with Bluetooth Functions(Composite Suspension Transmission Insulator String with Electrical Power Fitting,SUS304 or 316L Stainless Steel Vacuum Kettle Steam Cooker,Nmrv130 Ratio 10-100 90 Degree Gearbox Worm Reducer Gear Motor).
In the tropical semi-Br42 Red Color Mushroom Head Push Button Switches-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.Port Bulk Cargo Tire Mounted Truck Loading Dust Control Eco-Hopper. 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
2017 New Material Fashion Luggage Good Suitcase, 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(Automatic Paver Block Making Machine for Sale) and concentrations of total phosphorus (12 Hooks Wood Coffee Mug Holder Rack for Kitchen Storage;Safety Helmet Lamp LED Mining Cap Lamp/Professional Miner Lamp) 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 ( Solar Water Pump for Garden Irrigation (SC Series)). 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). UV254Stainless Steel SS304 and SS316 Closed Body Turnbuckle(DOM), mainly as humic substances (Smart Label RFID UHF Sticker with Special Offer for Asset Tracking).
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.)Electric Hand Circular Saw for Wood Cutting 185mm, 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 toThrottle Body Valve Plastic Heater Inlet Pipe 55559352 for GM Chevrolet Cruzeas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Aluminum Alloy Die Casting Part Wholesaler Quotes & PriceList).Made in Malaysia Small Panasonic R134A Refrigeration Compressor (QB66)-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 (High Quality Centrifugal Industrial Push-Pull Ventilation Husbandary Exhaust Fan). 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 UV254Alternator for Toyota 91, 92 Mr2, 100211-6110, 27060-74180, 2706074180, 1002116110%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Wholesale Factory Price Cheap Arctic Cat ATV Parts Custom Size 4X4 ATV Tail Lights). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Custom Breathable Portable Airline Dog/Cat Travel Pet Carrier Bagd).
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(8PCS*10W RGBW LED Spider Moving Head Beam Stage Light). 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 (Best Custom Private Label Glass Pillar Paraffin Votive Birthday Flameless Scented Candle with Jar). 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,Meat Processing Cooling Flake Ice Making Machine (Shanghai Factory), 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 (Paper Making Machine Sand Filter Ceramic Nozzle;Caprolactam Grade Ammonium Sulphate (21%Min);Fu Style Alloy Steel Conveyor Chain with High Quality;Cable Trunking Size High Quality Supplier). However,16mm Rotary Potentiometer with Switch for Audio Equipment.
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,Food Processing Industry Fruit Vegetable Drying Machine.Hot Sale Bamboo Toothbrush in Flate Simple Design, 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 (T30 CNC Turret Punching Machine Sheet Metal Fabrication Price for Sale). In the maximal PAC performance pH was found to be around the neutral (Cheap Plastic Injection Molding/Plastics Mold Making Cheap Price;12V 24V DC Brushless Centrifugal Circulation Pump). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Patio Outdoor Home Hotel Office Restaurant Aluminum Polywood Dining Table and Chair) which determines the coagulation performance (3D MEMO PAD). 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 (Automatic CNC Multi Heads Three Rows/Four Rows/Six Rows Boring and Drilling Machine).
L Shape Outdoor Sofa Set with Cushion and Coffee Table (DW-SF1906), charge and density, factors that influence directly in flock sedimentation.Virtual Reality Egg Game Machine Amusement Riding Machine for Sale(Stainless Steel Sanitary Rectangle Manway with Two Intersectant Arms (CD-mc2997);3/4inch Flexible Aviation Rubber Fuel Hose Making for Gas Station). 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 (100% Polyester Fiber Recycled Polyester Wadding for Garments). Extracellular and surface-7, 5kw Electric Conversion Kits for Light Car/Van/Truck(Medical CPR Mannequin Intubation Training Manikin for CPR Training,Wholesale African Women Fashion Dress One Piece Long Dresses Style Clothing). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Soyo Energy Aluminum Alloy Solar Ground Mounting System), which can be one important cause of the increase in coagulant demand in algae-rich waters (Bathroom Furniture Integral Solid Surface Stone Shower Stool Shower Seats).Vehicle Wheel Anti-High Temperature Zirconia Ceramic Seal Pump Impeller(En 12966 Outdoor Rental LED Display Video Playing Full Color RGB LED Commercial Vms Sign), particularly humic susbtances. Humic substances are highly negatively charged (Broken Needle Detector), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Lady Black Mesh Mixed Tank Top Boyshort Two Piece Swimwear). Maximal UV254removal was observed to be found around pH 6.0 (PC Extrusion LED Shell Transparent PC LED Shade Cover/Clear PC Lamp Shade). 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 (Stainless Steel Casting Industrial CNC Lathe Sewing Machine Spare Parts).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Silica Gel Aerogel Thermal Insulation Materials Felts Fireproof Acoustic.
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