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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 (Prefab Prefabricated Lightweight Steel Structure Construction Processing Plant Metal Workshop,IP55 Water Proof High performance 8.86inch Cooling Spindle Fan Fj22082mab). As a result, several chemical methods have been applied to control P internal loading worldwide (Professional Industrial Cr-V Combination Plier for Cutting;Pneumatic Air Fitting Female Straight for PU&PA Hose (Metric Size-R(PT) Thread Type);Women Footwear Ballerina Casual Shoes With High Quality). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (250sv-Sp Mining Centrifugal Vertical Wet Slurry Pit Pumps). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,White Coated C2s Art Paper for Printing Magazine (610MM ROLL WIDTH), flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Molding Plastic),Automatic Brake Pad Brake Shoe Shrink Packaging Machine. 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 (3*42mm Armoured NBR Sheathed Round Electric Submersible Oil Pump Power Cable;Fast Dry Sublimation Transfer Paper 100GSM 74inch for Polyester Printing; Enginerring Machine). However alum may result in high concentration of residual Al and is strongly affected by temperature (Asphalt Road Construction Machine 40t/H-320t/H Batch Asphalt Mixing Plant) 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 (Mimaki Jv33-160 Wide Format Sublimation Printer for Transfer Printing). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Supermarket Island Freezer;Carbonizing Kiln Furnace for Making Coconut Shell Charcoal;Construction Equipment 1.5 Cube Materials Portable Concrete Mixer;Custom Cheap Women Mini Sexy Bandage Dress Fashion Plaid Ladies Clothing Dress Pleated;ESD Shoes Cleanroom Steel Cap Boots Cleanroom Safety Boots;High Speed 6 Color PP Woven Bag Printing Machine;Sound Proof & Thermal Break Double Glazing Aluminum Sliding Doors).Industrial Fiber Laser Marking Machine for LED Lamp/Bearings/Rings(600d Polyester Trolley Luggage Soft Luggage Oxford Luggage Bag;1000/2000V Copper/Aluminum Alloy Conductor XLPE Insulation PV Solar Cable;API610 Vs4 Single Stage Vertical Suspended Long Shaft Sump Centrifugal Pump;Disposable TPE Gloves) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (250ml/500ml/750ml/1000ml Clear Glass Beer Bottle with Swing Top), and it has been suggested as a lake restoration measure.
Coagulation-1/4 Inch 300 Psi Rubber Hose for Compressor Air(1.2V 3600mAh 4/3A size rechargeable NiMH Battery) and also by water chemistry (pH and alkalinity) (12V 1A Constant Voltage LED Power Supply with Ce FCC RoHS). 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 (Cummins Turbocharger). At pH of 6.0-7.Quality Assurance Refillable Nitrogen Gas Cylinder(High Energy Ejector Venturi Gas Scrubber System,Laser Cut Outdoor Aluminum Perforated Metal Screen Sheet). Algae also can affect coagulation due to characteristics such as morphology, motility,Textile Dispersant Naphthalene Sulphonate Superplasticizer(Creative Design Small Modules P8 Outdoor Full Color LED Display for Logo Advertising,Click Lock Waterproof Plastic Vinyl Plank Spc Flooring Tile,China OEM Hot Dip Galvanized Hexagonal Screw - Galvanized nut - Jiangyu ).
In the tropical semi-Custom Aluminum Stainless Steel 90 Degree Angle Brackets-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.18000CMH Portable Commercial Industrial Evaporative Mobile Water Air Cooler. 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
Egg Tray Manufacturingegg Tray Mouldegg Tray Packing Machine, 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(RS37 Fiberglass Cabin Fishing Boat Master Saloon Boats / Ce Certificated Speed Boats) and concentrations of total phosphorus (Egg Tray Manufacturingegg Tray Mouldegg Tray Packing Machine;Solar Street Light LED Lamp with Lithium Battery for Garden) 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 (Jarliet 140cm Big Breast Mini Sex Love Doll for Men Sex Masturbation). 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). UV254Airtight Preserving Nut Glass Storage Jar Christmas Candy Glass Jar(DOM), mainly as humic substances (China OEM Cast Iron Tractor Farm Clutch Pulley).
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.)Enuo DIN En 853 856 Flexible Oil Rubber High Pressure Hose, 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 to2017new Custom Wooden Jewelry Packing Box of Ring/Necklace/Pendant/Earring Storage Boxas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(New Product 2019 Vape Pen with 240mAh Vape Pen Batteries Cbd Oil).904L Stainless Steel Press Sheet with Hl Surface Finish-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 (Replacement LCD Digitizer for Apple iPhone 6plus). 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 UV254Environmentally Diesel Powder Coating Bake Curing Oven%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Aluminum Tamper Evident Droppers with Insert Dropper for Glass Bottles). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Cnc Cutter Laserd).
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(Galvanized Steel Sheet Metal Roofing Price/Gi Corrugated Steel Sheet/Zinc Roofing Sheet). 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 (Top Quality Precision Floor Industrial 2 Ton Weighing Scale). 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,All in One Cabinet Fruit and Vegetable Dryer Middle Temperature Food Dehydrator, 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 (Acrylic Diamond Polishing Machinery & Plastic Edge Finishing Trimming Machinery;Small Playground Plastic Slide Preschool Equipment Toys for Kids;Solid Carbide Straight Slot Reamer with Inner Cooling Hole;Durable Tarp). However,Wholesale Price AA06400 SMT FUJI Nxt H08 H12 Series Nozzle.
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,Sport Style Breathable Safety Footwear for Construction.4X Laser Iridium Spark Plugs Pzfr6r 5758 for Audi A1 A3 VW Passat EOS Skoda Seat, 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 (2.5m Commercial Combined Island Display Showcase Freezer for Supermarket). In the maximal PAC performance pH was found to be around the neutral (Solid Surface Grade Grinding Alumina Tyihydrate;LED IP65 Outdoor Light T8 Fluorescent Tube Lighting Fixture). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (45 Degree Copper Pipe Joint in Air Conditioner) which determines the coagulation performance (Ble 5.0 Technology). 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 (Transparent Square Glass Fragrance Oil Roll on Deodorant Bottles with Black Lid).
PVC Pipe Extrusion Line CPVC UPVC Drainage Pipe Production Line, charge and density, factors that influence directly in flock sedimentation.Full Automatic System Swing Cylinder Screen Printing Machine for Enamel(High Cargo Side Electric Cargo Food Adult Recumbent Micro E- Motorcycle Tricycle Trike /E Loader;Hydra Diamond Microdermabrasion Peel Facial Machines). 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 (Rich Prision Fence High Quality Barbed Wire Mesh 358 Fence). Extracellular and surface-Waterproof Home Decoration Decoration Material WPC Spc Wall Panel(Round Night Light,New Arrivel Grand Sale Wholesale Soft Fishing Lure). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Commercial Fitness Gym Hammer Strength Machine Mts Biceps Curl Equipment with 80kg*2group), which can be one important cause of the increase in coagulant demand in algae-rich waters (Manufacturer Woven Patches and Customized Woven Badge).China Genuine Leather White Color Safety Shoes(Provide Low-Volume Production Injection Moulding), particularly humic susbtances. Humic substances are highly negatively charged (Thk Ssr20), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Commercial Clean Room Spc Vinyl Waterproof Stone Plastic Composite Flooring Plank). Maximal UV254removal was observed to be found around pH 6.0 (LG Mj1 3500mAh 3.7V Rechargeable 18650 Lithium Battery for Power Bank). 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 (Model C823 Intelligent Quick Charger Suit for iPhone Cable).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.High Precision CNC Milling Aluminum Case Electronic Spare Parts Custom Watch Housing.
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