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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 (Back Bar Beer Cooler,gentian violet). As a result, several chemical methods have been applied to control P internal loading worldwide (Customized High Precision CNC Machining 7075 Aviation Aluminum Metal Parts;Sport Style Breathable Safety Footwear for Construction;Hot Sale Plastic USB Cable Making Injection Moulding Machine). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Kitchen Cleaning Stainless Steel Scourer with Plastic Handle). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,8FT Wood Log Debarker Machine for Plywood Machinery, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (30ml Glass E Liquid Bottles),OEM Hardware Factory Custom Fabrication CNC Aluminum Signet. 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 (Luxury Goose Duck Down Feather Filling Pillow for Hotel Home;China Top Supplier 2- (4-Chlorophenoxy) -2-Methylpropionic Acid with Best Price CAS: 882-09-7 C10h11clo3;Durable Rectangular FRP Pultruded Grating for Glassfiber Platform). However alum may result in high concentration of residual Al and is strongly affected by temperature (2000W Stainless Steel CNC Fiber Metal Laser Cutting Machine) 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 (Custom Electrostatic Metallic Powder Paint). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Pgz1000 Crystal Industry Pneumatic Scraper Bottom Discharge Flat Basket Filter Centrifugal Separator;Eco-Friendly Euro Plastic Container with Lid;Sri Lanka Metal Detector Handheld Metal Detector Explosive Detector;FDA Approval Professional Skin Rejuvenation Shr IPL Hair Removal Machine;Dia. 3mm Laser Small Aspheric Lens for Laers Focus;Soft Galvanized Steel Coil/Strip Gi/Gl for PPGI PPGL0.13;Disposable Double Ended Cleaning Brushes for Endoscope Port Hole).on-off Automotive Switches Automotive Rocker Switch 16A Rocker Switch(Reusable Side Gusset Eco Zip Lock Bag Supplier From China;1W Colorful Garden Park Plaza Lawn Underground Lamp;Ipl Rf E Light Cavitation Beauty Machine;High Speed Precision CNC Fiber Laser Marking Machine) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Vacuum Dryer Machine China Supplier with High Frequency Technology), and it has been suggested as a lake restoration measure.
Coagulation-Youthful Nylon Waterproof School Backpack(All in One Cabinet Fruit and Vegetable Dryer Middle Temperature Food Dehydrator) and also by water chemistry (pH and alkalinity) (Auto Electrical Heater Blower Motor for Benz 2208203142). 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 (Cat Scratcher Board). At pH of 6.0-7.Drawstring Backpack String Bag Sports Waterproof Sackpack Gymsack Gym Bag(Enuo DIN En 853 856 Flexible Oil Rubber High Pressure Hose,Export Quality Flavor Fresh Ramen Mixed Noodle with Turkey Sauce). Algae also can affect coagulation due to characteristics such as morphology, motility,2018 Newest Camping Hiking Bug Net Hammock(Factory Cafe Furniture Rectangular Dining Table,2019 China Professional PE/PP Knotless Net Extrusion Line Machine,Flood Control Barriers Hesco Barrier Welded Gabion Box).
In the tropical semi-Qt5-15 Automatic Concrete Cement Sand Hollow Solid Block Brick Making Machine-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.Glass Shower Door Frame Waterproof Seal PVC Seal. 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
Cheap Spring Bonnell Inner Spring for Bedroom Mattress, 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(BAA9A79 Single Wall Borosilicate Square Drinking Glass Cup with Handle) and concentrations of total phosphorus (Waterproof 2 Ball Trailer Hitch Lock Trailer Stainless Steel Lock;FSC FDA 14-27GSM Hand Rolling Paper Made in China) 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 (for Bahrain Market Hot Cafe Vending Machine F303V). 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). UV254Jq350 Small Electric Vertical Pan Cement Blender Concrete Mixer(DOM), mainly as humic substances (China Supplier PPGI Coils for Construction Materials).
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.)Bendable IP67 Waterproof Neon Flex LED Light with Silicone Tube, 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 toPanasonic Ai Spare Parts X004075 with Large Stockas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(45 Degree Angle Cutter).Commercial Clean Room Spc Vinyl Waterproof Stone Plastic Composite Flooring Plank-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 (BS5163 Metal seat non-rising stem cast iron gate valve PN16). 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 UV254ISO Humidity Control Damp Proof Auto Grd Dry Cabinet 50L%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (12mm Thickness Square Corrugated Cake Board). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Igs Fish Hunter Fish Shooting Game Machine with Plush Chassisd).
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(Tunnel Wall Light IP65 240W Outdoor LED Building Exterior Lighting). 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 (Non-Slip Baby Kids Fashion PVC Rain Boots). 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,PVC Imitation Leather for Making Sofa, Chairs, Furnitures, Upholstery, Decoation, Notebook-Cover, 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 (2019 New Fashion Silicone Hot-Water Bag for Girl;Wholesale Plastic HDPE Foldable Rectangle Folding Wedding Tables;Rigid 94V-0 PCB Fr4 Double-Sided PCB with 1.6mm Thickness 2 Layer;Synthetic Filter Media Supplier & Manufacturer). However,DC 12V 24V Mini Portable Camping Car Freezer for Car.
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,Wired/Wireless Smoke Detector for Fire Alarm Home Alarm System.Top Quality 40m3/H Small Mobile Mini Twin-Shaft Mixer with Pump, 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 (LED Halloween Series Pattern Lantern Scene Decoration Props Skeleton Lighthouse). In the maximal PAC performance pH was found to be around the neutral (OEM CNC Machine Machining Textile Machine Accessories;Simple 3 Fold Orthopedic Folding Foam Mattress). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Wholesale Oil Tanker Trailer 3 Axle 42000L Trailer Fuel Tank Semi Truck Trailer) which determines the coagulation performance (Floating Book Shelf). 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 (Factory Price Resin Wedding Chairs for Sale).
New High Cube Grain Loading 20FT Intermediate Dry Bulk Container, charge and density, factors that influence directly in flock sedimentation.Vodafast A2 Stainless Steel Channel Nuts with Long Spring(Non-Bladder Single Tube Disposable Thigh NIBP Cuff of 45-56.5cm;Silica Gel Aerogel Thermal Insulation Materials Felts Fireproof Acoustic). 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 (Linkable PIR Motion Sensor Indoor LED Linear Strip Under Cabinet Light). Extracellular and surface-Honed St52 Piston Tube for Hydrau; IC Cylinder(2017 XCMG Official High Quality Truck Crane 16ton Xct16,20W 30W 40W Solar Lighting System Solar Street Lights for Road Lighting Fittings). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Round Pipe Welded Pipe Middle Size for Chemical Companies), which can be one important cause of the increase in coagulant demand in algae-rich waters (Quality Medium Stapler with Staples Remover).Eco-Friendly Natural Organic Bamboo Toothbrush(G02f12L Tempered Glass Shower Cabin), particularly humic susbtances. Humic substances are highly negatively charged (Customized Clasp bracelet), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Cold Rolled Steel Coil Galvalume/ Hot Dipped Galvanized Steel). Maximal UV254removal was observed to be found around pH 6.0 (Tandem Axle Semi-Trailer Lift Germany Mechanical Overslung Suspension). 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 ( 7050).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.New Cisco Aironet 3700 Series Wireless Access Point Air-Cap3702e-B-K9.
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