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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 (Disc Neodymium N35 N45 N40 N42 N38 N48 N52,m.cnfivestars.com). As a result, several chemical methods have been applied to control P internal loading worldwide (Factory Price 304 304L 316 316L 321 Inox Stainless Steel Coil / Sheet / Plate;Double Sided Heat Tape for Electrical Adhesive Masking Packing Tape;Wholesale Price of Benzyl Benzoate Powder Provide Sample Packing for Test). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Small Silent Biogas Electric Generator for Biogas Plant). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,LED Screen Facial Comedo Nose Blackhead Cleanser Zit Extractor Tool, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Voltage Stabilizer 10 Kva),Custom Dye Sublimation Printed Phone Lanyard ID Badge Holder with Logo Custom. 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 (Factory Ultrasonic Herb Solvent Extraction Equipment with Discount;Dual 2 Cubic Meters Precast Concrete Mixer Batching Plant Machinery Manufacturer; Aluminum etc.). However alum may result in high concentration of residual Al and is strongly affected by temperature (Ktz Series Best Slurry Pump Sewage Submersible Pump) 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 (Automatic Square Rectangle Color Card Cutting Machine). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (High Quality Genuine Leather Luxury Casual Shoes Sneaker for Men Fashion Sneaker Shoes for Men; Clear Textured Slip Resistant Strips;Packaging Tea Tin Box Blank Round Tin Cans Small Empty Coffee Food Grade Mini Sealed Gift Boxes;Best Seller Sex Pregnant Women Adult Sex Dolls Adult Love Doll Softest 158;Drugs Medical Cart For Sale;High Quality Prefabricated High Rise Steel Structure Apartments Hotel Building;Long Range RFID Access Control Card for Non-Stop Parking).Auditorium Chairs for Public Furnitures, School Furnitures, School Chairs (R-6130)(Used Cat Loader Caterpillar 966h Wheel Loader for Construction;Electronic Leak Detector Sf6 Gas Leak Detector So2 Analyzer;insharevape;ASTM A335 P11 Seamless Ferritic Alloy-Steel Pipe for High-Temperature Service) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Stainless Steel Galvanized Perforated Metal Sheets), and it has been suggested as a lake restoration measure.
Coagulation-Chrome Steel Cam Follower CF4 for Machine Parts(Best Factory Price Metallic Honor Medal with Neck Ribbon) and also by water chemistry (pH and alkalinity) (Water Play Equipment Inflatable Gym Air Track Mat). 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 (Vacuum Kneading Rotary Piston Pump Combination Sets). At pH of 6.0-7.Electric Baking Heat Preservation Deck Oven Manufacture(50 Bend PVC Pipe/Belling PVC Pipe/Making Machine,Best Quality PCB Design and Production Manufacturer Consumer Electronics PCBA Boards). Algae also can affect coagulation due to characteristics such as morphology, motility,2019 Hot Sale Door Motion-Sensor Floodlight(Wall Mounted Bathroom Tissue Holder Toilet Paper Towel Roll Holder,Colorful Glass Straw Drinking Straw Reusable Borosilicate Glass,Stainless Steel Threaded Vertical Check Valve 1/2-4 Inch).
In the tropical semi-Pond Electric Copper Wire Clean Water Pump with European Plug-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.Automatic Multi Function Side Drilling Machine. 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
Resealable Ziplock Round Bottom Biodegradable Food Packaging Pouch Wholesale in China, 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(Pedstal Electric Stand Fan 5 Speed Control Air Cooler) and concentrations of total phosphorus (Manufacturers Sell Direct Bullet Design Red Hollow Crown Lipstick Tube;China Aluminium Outdoor Event Party Tent for Activity) 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 (Commercial Industrial Fast Food Chicken Electric Gas Pressure Deep Fryer for Mijiagao). 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). UV254Yaye 18 Hot Sell Waterproof 300W CREE LED High Bay Light /300W LED High Bay Lighting with Ce/RoHS(DOM), mainly as humic substances (20HP Copeland Scroll Compressor Zr250kce-Tw7-522).
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.)Wholesale Fashion Designer Customs Sunglasses Square Men Sunglasses, 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 toWomen Footwear Ballerina Casual Shoes With High Qualityas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Precise Fiber Laser Cutting Machine).Rechargeable Battery Powered Indoor WiFi Camera with Custom APP-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 (Fast Dry Sublimation Transfer Paper 100GSM 74inch for Polyester Printing). 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 UV254Luxury Design 70GSM 110GSM 3D Bedding Bed Sheet%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir ( Enginerring Machine). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Double Acting Super High Pressure Hydraulic Presses Cylinder and Cylinder Partsd).
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(Supermarket Island Freezer). 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 (Carbonizing Kiln Furnace for Making Coconut Shell Charcoal). 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,Good Quality CNC Contour Sponge Foam Profile Vertical Cutting 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 (High Speed 6 Color PP Woven Bag Printing Machine;Sound Proof & Thermal Break Double Glazing Aluminum Sliding Doors;600d Polyester Trolley Luggage Soft Luggage Oxford Luggage Bag;Welded Steel Pipe). However,Professional Palm Handheld Veterinary Ultrasound Diagnostic System.
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,Custom Logo Small Beer Mug One Ounce Mini Stein Glass.PVC Coated Galvanized 12 Guage Iron Baling Wire, 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 (1000/2000V Copper/Aluminum Alloy Conductor XLPE Insulation PV Solar Cable). In the maximal PAC performance pH was found to be around the neutral (Disposable TPE Gloves;250ml/500ml/750ml/1000ml Clear Glass Beer Bottle with Swing Top). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (1.2V 3600mAh 4/3A size rechargeable NiMH Battery) which determines the coagulation performance (HRC50-55 Tungsten Steel Carbide Square End Mill and Carbide Ball End Mill). 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 (12V 1A Constant Voltage LED Power Supply with Ce FCC RoHS).
Kh CNC Plasma Cutting Machine 1530 CNC Controller, charge and density, factors that influence directly in flock sedimentation.High Quality Anti-UV Artificial Garden Grass Carpet(High Energy Ejector Venturi Gas Scrubber System;Laser Cut Outdoor Aluminum Perforated Metal Screen Sheet). 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 (Creative Design Small Modules P8 Outdoor Full Color LED Display for Logo Advertising). Extracellular and surface-Sw Type BOPP Packaging Adhesive Tape Coating Machine(High Quality Stainless Steel Architectural Ring Mesh,Click Lock Waterproof Plastic Vinyl Plank Spc Flooring Tile). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Cold Rolled Wholesale Price Stainless Steel Sheet 316 MOQ 1PC), which can be one important cause of the increase in coagulant demand in algae-rich waters (Star Necklace Jewelry Wholesale Fashion 925 Sterling Silver Necklace Jewelry).19mm Fancy Plywood for Door Use and Whole House Decorative(RS37 Fiberglass Cabin Fishing Boat Master Saloon Boats / Ce Certificated Speed Boats), particularly humic susbtances. Humic substances are highly negatively charged (Mobile Phone Accessories for iPad Leather Case), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Egg Tray Manufacturingegg Tray Mouldegg Tray Packing Machine). Maximal UV254removal was observed to be found around pH 6.0 (Morden Aluminum Frame Hotel Sectional Corner Sofa Garden Rattan Outdoor Furniture). 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 (Ideabond Aluminum Composite Panel Brushed Series).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Left Door Lock Set Key for Land Rover Discovery 4 Auto Modified Car Door Lock Cylinder.
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