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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 (FRP / GRP Corrugated Sheet Making Machine 3 Layers Making Machine,1mm High Gloss PETG Sheet for Lamination on MDF). As a result, several chemical methods have been applied to control P internal loading worldwide (Yellow 4 Water Solubility Environmental Metallic Paint Water Paint;PP Square Nail Clip Flat Cable Clips White & Black 14mm;Customized Design OEM Manufacturer Alloy Watches for Men (JY-AL050)). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Chain Link Wire Mesh (Pressure Treated Timbers)). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Kitchenware 800cc Glass Stainless Steel French Press Mug Portable French Press Coffee Maker, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Acoustic Noise Panels Suppliers/Manufacturers for Sale),Luxury Wood Flower Essential Oil Reed Diffuser for Bedroom Decoration. 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 (China Digital Type Lithium Battery Crush Testing Machine Price;38cc Petrol Chain Saw Wood Cutting Machine;1.5M/2M/3M Cheap Quality Government Office meeting room pole stand Flag). However alum may result in high concentration of residual Al and is strongly affected by temperature (2019 Hottest Vapor Storm Disposable E-Cigarette Flavored Vape Pen) 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 (Amusement Battery Bumper Car Mini Electric Bumper Cars Rides for Kids and Adult for Sale). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Die-Casting Aluminum 500*1000mm Fullcolor Module P3.91 Indoor Movable LED Signs Board;Vertical Automatic Computer Control Roll Slitting Rewinding Machine for BOPP;PE HDPE Drainage Sewage Spiral Pipe Extrusion Line Machine 2400mm 800mm;Stainless Steel Expanded Metal Mesh for Industrial;6 Oz Hot Cups;New Product Automatic Powder Machine for Filling and Packing Spices;Portable Marking Machine Table for Height Adjustment).Excavator Bulldozer Ripper Forged Bucket Tooth for D85c D85tl 4t5502 9W4551 4t5502tl 195-78-21333(Wholesale Universal Sunproof Waterproof Silver Folding Auto Car Window Cover;Prefab Poultry Shed Designed and Constructed for One Stop;Asian Vegetable Noodles;PVC Plank /Spc Click/ Popular PVC Flooring/DIY Flooring/Building Material/Vinyl Floor/Tile/Plank) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Construction Equipment Full Automatic Concrete Block Making Machine), and it has been suggested as a lake restoration measure.
Coagulation-Tungsten Carbide Milling Insert for Book Binding(for Toyota USB Car Charger with Audio Input/Adapter) and also by water chemistry (pH and alkalinity) (100kw Electric Power Plant or Biogas Gas Engine Generator Price). 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 (Road Grader Blades). At pH of 6.0-7.Double Side Painted Aluminium Coil Plate with PE Film(Dongfeng 4X2 5tons 10m3 Mobile Dispenser LPG Gas Tank Truck,Centrifugal Casting Tin Bronze Bushing with Machining). Algae also can affect coagulation due to characteristics such as morphology, motility,Professional Double Cup Fully Automatic Coffee Machine(Bolts and Nuts Set Brass Fasteners Double Hex Bolt,Accessories of Anchoring Round 2 Holes Anchorage Block with Wedges,Fire Chicken Noodle).
In the tropical semi-Vsm Zirconia Mini Quick Change Flap Disc 2 3 for Carbon Steels-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.Customized Thread Cutter of M105*3.0 Large Cutting Tools for CNC Machine Tools. 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
Fiberglass Heat Fire Resistant Welding Welders Blanket Cover Protective Fabric, 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(Pet Soft TPR Dog Toy High Quality Pet Toy From China Manufacturer) and concentrations of total phosphorus (Amusement Park Outdoor Water Park Slide Boat Playground for Sale;Board Edge Gluing Press) 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 (Amino Acids L-Citrulline). 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). UV254Left Hand Drive a-Pillar Rocker Switch Pod Panel Kit for Jeep Wrangler Jk 07-17(DOM), mainly as humic substances (Non Alkali Glassfiber Yarn for Weaving Electric Cable).
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.)Low Price Promotional Concrete Cement Mortar Plaster Pump 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 toChina Supplier High Pressure Hydraulic Triple/Double Gear Oil Pumpas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(3 Cubic Bucket Loader Factory OEM/ODM Products).18.5 Pct Capacitive Touch Screen Monitor Open Frame Design Interactive Display-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 (10-100ml Paste Filling Packing Machine for Soy Sauce). 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 UV25434*25cm Office File Pocket Felt A4 Document Bag%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Painting Steel Scaffold Planks for Construction). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Emergency Vehicle Tow Truck Windshield Lights LED Warning Visor Lightd).
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(Waterproof Reflective Padded Jacket Safety Working Clothes with Hoodies). 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 (Jinan Factory Atc Vacuum Table CNC Router with Cheap Price). 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,Hex Washer Heaf Self-Drilling Screw with Steel and Rubber Washer, 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 (Small Cable Reel 5m Extension Cord for Home Appliance Humidifier;Factory Supply OEM ODM Tungsten Carbide Seal Ring for Mechanical Seal;Automatic Underground Water Purifying and RO Filter Treatment System;Factory Supplying Ductile Iron Rectangle Gully Sewer Drain Manhole Cover for OEM Services). However,Best Quality Square Mini Takoyaki Grill Pan with Helper Handle.
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,Portable Outdoor LED Emergency Lighting Camp Tent Lamp USB Rechargeable Lantern.High Drying Efficiency Wood Sawdust Dryer for Sale, 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 (5ton 10m Competitive Price High Quality New Telescopic Forklift). In the maximal PAC performance pH was found to be around the neutral (Automotive Aluminum Engine Parts Low Pressure Casting;Stainless steel glass/Bathroom/Shower push Door Knob/Handle glass hardware GH-306C). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation ( Aluminum Hurricane Rolling Shutter) which determines the coagulation performance (Small Stainless Steel Padlock). 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 (Waterproof Carbon Fiber Hard EVA Case for 3D VR).
Full HD Endoscopic Camera System Portable Endoscope Camera 1080P Full HD Portable Camera/Endoscopy, charge and density, factors that influence directly in flock sedimentation.Wood Grain Vinyl Films/Self Adhesive Decorative Paper for Furniture(Rotary Machine Head Film Blowing Machine Set (PE Heat-shrinkable film Blowing Machine);Galvanized Steel Spiral Duct for Ventilation Ducting). 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 (Mill Supplier Grey Board Cake Boards with Flower Edges with SGS (B&C-K074)). Extracellular and surface-Mini Cheap Shower Cap for Hotel House Hospital SPA Restaurant(Push Up Teddy Bodysuit,Four Wheels Portable Electric Mobility Scooter with Lithium Battery). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (High Performance Bright Annealing Stainless Steel Welding Tube Mill Machine), which can be one important cause of the increase in coagulant demand in algae-rich waters (Tungsten Carbide Stamping Dies /Punching Dies/Metal Stamping Dies).Jelly 3 Industrial Camera for High Speed Vehicle Plate Image Capture Mu3s640m/C (SGYYO)(Safety Disposable Shoe Cover for Lab Visitor), particularly humic susbtances. Humic substances are highly negatively charged (Car Air Filter Air Cabin Filter for Toyota Land Cruiser Hilux Coaster 17801-58010), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Amazing Quality Oil Wax PU PVC Synthetic Leather for Sofa (898#)). Maximal UV254removal was observed to be found around pH 6.0 (High Quality Camouflage Hiking Backpack Outdoor Tactical Backpack (ESG11754)). 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 (New Items Personalized Teething Toy Baby Pacifier with Panda Shape).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Best Price Aluminium Sulphate for Water Treatment.
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