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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 (Stainless Steel Patient Record File Folder Medical Chart Holder,Biomass Pellet Production Line). As a result, several chemical methods have been applied to control P internal loading worldwide (Digital Electronic Body Fat Personal Bluetooth Health Weighing Scale (SBF097BT-WTP);Bright Polished Galvanzied Common Iron Wire Nails;Wallbox Socket Type 2 32A 22kw Three Phase EV Charger for Smart Charge). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Environmental Protection Material PLA Sheet for Cup Lid Tray Forming). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Textile Waterproof Motorcycle Trousers for Sale, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Adult Cup with Space Cup Gymnasium Water Cup),Mobile Phone Jammer + WiFi / GPS / 4G Jammer 6 Bands, Higher Gain Antenna100% Waterproof Outdoor Jammer. 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 (Amusement Park Best Electronic Washing Ball Clean Dry Machine Cleaning Ball Machine;Bestsub Sublimation Square Ceramic Coaster W/ Cork (CBZ24);8 Inch Carbon Mechanical Properties of St35 Schedule 40 Steel Pipe). However alum may result in high concentration of residual Al and is strongly affected by temperature (Portable Aluminum Airbag Used Air Compressor Tank for 12V Air Compressors) 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 (Flange Adaptor Water PE Stub End HDPE Fitting Water Supply). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Double Head Half/Full Threaded/Eye Wooden/Truss/Hex/Pan Self-Drilling/Tapping Screw;Good Price Automatic Liquid Sachet Juice Milk Drinking Water Pouch Filling Packing Packaging Machine;Pulse Cartridge Filter Lower Noise for Explosion Proof Dust Collector;Good Performance High Precision Thrust Roller Bearing (29292);No Needle Injection Gun Hyaluron Injection Pen for Hyaluronic Acid Injection Skin Rejuvenation;30% Al2O3 Content Yellow PAC for Wastewater Treatment;ASTM Good Price Carbon Steel Carbon Stainless Steel Pipe in Hot Selling).Customized Silicone Rubber O-Ring Seal Sealing Housing Gasket(50*50*25mm Strong Neodymium Block N35 Permanent NdFeB Magnet for Sale;Precise Profile Wire Universal Rolling Mill;Wooden Kids Outdoor Playground;Popular Blue Colour Changing Raw Material 1-3/2-4/3-5mm Silica Gel Desiccant) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Semi Electric Pallet Stacker Price 2 Ton Pallet Forklift), and it has been suggested as a lake restoration measure.
Coagulation-Chiller Price Water Cooling System Screw Air Cooled(Sinicline Custom Printing Display Packaging Self-Sealing Plastic Bag) and also by water chemistry (pH and alkalinity) (Hot Sale Mimaki Ujf-A3hg UV LED Curing Platform Inkjet Printer). 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 (Buy Brown Paper Bags). At pH of 6.0-7.Wholesale Price Ce RoHS Promotional Ultrasonic Humidifier Aromatherapy Diffuser(Classic Cafe Dining Chair with High Quality/Grey/Arm Chair,Factory Directly Custom Promotional Cheap Bulk Buy Silicone Wristband Mould). Algae also can affect coagulation due to characteristics such as morphology, motility,Custom OEM Sheet Metal Stainless Steel Aluminium Sheet CNC Laser Cutting Service(Cosmetic OEM Gold Pet Foam Bottle for Cosmetic Packaging and Face Cleam,Automatic Turntable Continouse Blast Cabinets Belt Sandblaster Sandblasting Machine,bagasse fired steam boiler).
In the tropical semi-Letter Size A4 Adhesive Sticker Shipping Self Adhesive Paper Labels-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.White Frame 43 Full HD LCD Ad Player Advertising Digital Signage Interactive Totem. 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
Industry Basket Washing Machine Crate Washer, 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(High Quality Standard Cum B3.3 Water Temperature Sensor for Excavator) and concentrations of total phosphorus (Custom Machining Service Machined Parts High Precision CNC Milling Process;6X2500 mm Hydraulic Shearing Machine for Cutting Metal Plate with Ce Cetificate) 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 (Lightweight Camouflage Outdoor Combat Military Tactical Molle Vest). 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). UV254250ml Medical Transparent Ultrasound Ultrasonic ECG Gel Wholesale Price(DOM), mainly as humic substances (Wholesaler HRC60 Carbide Corner Radius End Mills Chamferied Cutter).
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.)High Density Storage Rack Heavy Duty Drive in Pallet Racking System Design, 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 toHigh-Grade Hemp Rope Hanging Grain General Twine Hanging Grain Spotas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(5 Gallon Water Bottle Storage).3L 5L 7lstainless Steel Vertical Manual Meat Stuffer Sausage Filler-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 (2018 Chinese Single Person Best Plastic Fishing Kayak Sit on Top). 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 UV254Qtj4-40 Mobile Block Making Machine Price List/Cement Block Maker Machine/Small Manual Block%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Pink Strapless Dress Trumpet Sleeves Sweet Party Luxury Prom Dress). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Rubber Two Roll Mixing Mills Machined).
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(High Speed Promotional Plastic Custom USB Flash Drive U016/Sy015). 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 (Home Furniture Metal Chair Grey Velvet Dining Chair). 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 Price U Shape Duct Line 5 HVAC 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 (Auto Parts Belt Tensioner and Pulley OEM 0002021719 for W204 C250 Slk250;C1022A Bugle Head Coarse Thread Gypsum Board Screw 3.5*25mm;KCD-108 Series for Home Appliance Colourful Rocker Switch;Aluminum Foil Coil). However,Newest Double Color WPC 3D Wood Grain Plastic Composite Flooring.
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,ACP/ACP Sheet/Aluminum Composite Panel Manufacturer.Matt Print Foil Coffee Bags with Valve Flat Bottom Zipper, 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 (High Quality Watermark Brass Square Bottle Trap in Gold). In the maximal PAC performance pH was found to be around the neutral (Stainless Steel Checkered Plate 304 316L 410 Floor Material;Snowkey Meat Processing Cooling Flake Ice Making Machine). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Custom Aluminum Die Casting Parts for Medical Equipment) which determines the coagulation performance (Metal Pylon Advertising Pylon). 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 (Strong Baby Banquet Chair for Hotel/Restaurant/Wedding/Home).
Ozone Generator Water Treatment Mineral Water Filter System, charge and density, factors that influence directly in flock sedimentation.Junction Plate Connect Board Bracket Stamping Made(J5 6-24V 27.8*46.6mm 10.64W DC Motor for Grass Cutter;2018 New Pet Supplier Warm Soft Canvas Flower Shape of PED Cat Dog Beds). 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 (Nylon Flashing LED Dog Leash with Night Light). Extracellular and surface-Reflective Police Protective Uniform for Working Vest(vtimejewelry,Aluminium Spigot Lighting Truss). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Yiwu China Promotional Items Corporate Gift Hat Promotional Cap (C2032)), which can be one important cause of the increase in coagulant demand in algae-rich waters (Hypoallergenic Polyester Duvet Insert for Hotel Bedding (DPF17060).Book Matched Marble Tiles Wall Design in Hotel Hall Natural Blue Macubas Marble Slab(Plastic Roofing), particularly humic susbtances. Humic substances are highly negatively charged (Gt-4510na 1.7 Inch Compression Driver for Line Array), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Good Quality Tungsten Carbide Round Nose End Mill). Maximal UV254removal was observed to be found around pH 6.0 (Liyyou Ly17 Cord-Free Lithium Battery Stick Upright Vacuum Cleaner). 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 (Automatic Food Canning Machine Tin Can Vauum Seamer).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Yako Brass Waterproof Balcony Toilet Bathroom Floor Drain.
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