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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 ( Chrome 04-7,Customized Food Grade Rectangular Metal Can Christmas Gift Tin Box with Ribbon for Chocolate Candy). As a result, several chemical methods have been applied to control P internal loading worldwide (Breathable Sport Wrist Protector Support Wraps Brace Sleeve;43L Big Volume Insulated Backpack Delivery Food/Pizza Bag;Durable Board of Roadway No Parking Sign Board PE Traffic Cone). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Oral Real Doll Adult Sex Products Male Masturbator). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,1616 Aluminum LED Strip Channel Surface Mount LED Extrusion, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Privacy Screen Iphone 12),600d Polyester Trolley Luggage Soft Luggage Oxford Luggage Bag. 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 (Dsr350g Top Aquaculture Pneumatic Conveying Pressurization Roots Energy-Saving Blower;OEM Service /High Quality Metal Dome /FPC Switch Silicone Push Button with LED;Factory Price Outdoor Wrought Iron Railings Top Quality Delicate Railing Design Metal Fencing). However alum may result in high concentration of residual Al and is strongly affected by temperature (2205 En1.4462 S32205 2507 En1.4410 S32750 S32760 En1.4501 Duplex Stainless Steel U Channel Bars) 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 (Factory Wholesale Barber Shop Shampoo Chair Hair Wash Chair). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (P5mm Creative Indoor 3D Effect LED Video DJ Booth LED Screen Display;1.2mm Thick Faux Suede Backing Shoes Leather Fabric;60W 6040 Engraving Machine Laser for Paper Cutter Machine;Inflatable Floating Water Playground Water Island for Commercial Business Usage;Containing Fabric Brighteners China Washing Powder Klin Detergent Powder;LCD Display Mine Metal Detector for Water Gold Silver Diamond; Steel Pressure Tube Pipe 25crmo4).Export Quality Flavor Fresh Ramen Mixed Noodle with Turkey Sauce(Abrasives Sandblast /S660 Cast Steel Shot for Shot Peening;2019 Bdu Army Camouflage Uniform with 3-Color Desert Color;Khaki Uniform Fabric;27.5′′ Lithium Battery Mountain Style Electric Bike) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Factory Wholesale Price Fingerprint Access Control with TCP/IP and WiFi), and it has been suggested as a lake restoration measure.
Coagulation-High Pressure Zirconia Ceramic Piston Rod Pump Ceramic(Full Automatic Silicon Sealant Sausage Film Filling and Sealing Machine) and also by water chemistry (pH and alkalinity) (Filter Press Machine for Sand Washer Sludge Dewatering Working Site in China). 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 (Bone Drill Used 4s2p 5200mAh 14.8V Lithium Battery Manufacturers). At pH of 6.0-7.Brown Shoes High Quality Strong Protection Working Shoes(Healong Fashion Sportswear Latest Design Blank Gym Sweatshirts Custom Cotton Hoody Sweatshirts,Padded and Comfortable Cushion Stainless Steel Carmeno Velvet Dining Chair). Algae also can affect coagulation due to characteristics such as morphology, motility,700ml Leak Proof Fitness Plastic Protein Mixing Water Cup (HDP-0346)(3G/H Ozone Generator for Air Purification and Sterilization,Greenpedel X1 Foldable Electric Scooter with Seat for Adults,High Quality Silicone Massage Function Cap Custom Waterproof Swim Cap).
In the tropical semi-4we5 Electrically Operated Directional Control Valves-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.Single Head High Speed Tubular Cap Embroidery Machine (TLC901). 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
Communication Cable Rg59/RG6/Rg11 Coaxial Cable Copper Standard Wire Satellite System, 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(Aqualand 8feet Inflatable Rubber Fishing Boat/Rowing Dinghy/Motor Boat (aql250)) and concentrations of total phosphorus (Transmission Parts Linear Ball Bearing with Shaft for Setting Machine;High Performance Natural GRP/FRP Pressure Tanks for Water Softner) 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 (Hot Sale High Density Hotel Cashmere Wool Polyester Blanket). 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). UV254High Speed LDPE Polyethylene Plastic Film Extrusion Machine(DOM), mainly as humic substances (220V UFO Shaped LED Bulb E27 Efficiently Energy Saving LED Light).
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.)Telescopic Aluminum Square Tent Pipe&Drape for Wedding/Event, 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 toFenugreek Extract Enhance Men′s Sexual Functionas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Wireless Tv Soundbar).Oven and BBQ Digital Cooking Thermometer with Stainless Steel Probe-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 (NF3). 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 UV254Caprolactam Grade Ammonium Sulphate (21%Min)%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Optical Solar Smoke Detector with Testing Button (ES-T601)). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Mini Wood Chipperd).
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(1.5 Inch High Pressure Petrol/Gasoline Water Pump). 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 (15kw 19kVA 50Hz Home Standby Weichai Soundproof Diesel Generator). 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,Micropile Tube as Umbrella for Tunnel Portal Od139.7mm Wt9mm, 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 (Tecjet Cloth Printer Printing Machine 6090 DTG Printer;Home Kitchen Appliance Digital Ozone Generator for Air Water Purifier;Hastelloy C276 Uns N10276 2.4819 Plate Bar Tube Nickel Alloy with China Supplier;China Ball Bearing Clutch). However,NdFeB Magnetic Strong Sintered N45 Rare Earth Permanent Neodymium Magnets for Motor.
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,Hexagon Commercial Nylon Carpet Tiles/Office Carpet Tiles/Sexangel Carpet Tiles.19 Inch IP65 Waterproof Design Industrial Tablet Computer for Industrial Automation Equipment, 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 (Good Quality Mixing Tank Vacuum Mixing Pot Mixing Reactor Vessel). In the maximal PAC performance pH was found to be around the neutral (Automotive Electropainting;Aluminium Radiator Core for Profile or Alloy LED Lighting Other). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (A694 F42 F52 F60 Class 3000 Forged Pipe Fitting Swaged Nipple) which determines the coagulation performance (Infrared Halogen Heater Lamp Electric Quartz Heater LED). 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 (Free Sample From Factory High Quality White Kaolin Clay Price).
Two Walls Stainless Steel Insulated Straw Cup Step Shape Metal Juice Cup with Straw, charge and density, factors that influence directly in flock sedimentation.100%Polyester Sublimation Short Sleeves Polo Shirt Custom Sports Golf T Shirt for Men(Fein Titanium Bi-Metal Oscillating Saw Blade;PVC Cross Joint Pipe Fittings Equal Pipe Cross). 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 (Customizable High Quality Q38 Series of Catenary Shot Blasting Machine). Extracellular and surface-Concrete Road Cutting Machine, Road Cutter, Road Saw Machine(Beach Clutch Bag,Left Door Lock Set Key for Land Rover Discovery 4 Auto Modified Car Door Lock Cylinder). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (PCB Mounting Shielded Modular Jack Ethernet RJ45 Connector), which can be one important cause of the increase in coagulant demand in algae-rich waters ( Fabric).Soyo Energy Aluminum Alloy Solar Ground Mounting System(3m 467MP Strong Adhesive Double Sided Transfer Tape), particularly humic susbtances. Humic substances are highly negatively charged (500L Combined Type Beer Brewing System for Sale), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Fertilizing Machine Farm Tractor Mounted CDR-1000 Fertilizer Spreader). Maximal UV254removal was observed to be found around pH 6.0 (Vending Machine 12.1 Inch Embedded or Open Frame Capacitive Touch Screen Monitor). 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 (Biodegradable Resealable Plastic Food Packaging with Zipper).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Hot Sale Stainlesss Steel Forged Pipe Nipple Threaded Nipple (KT0561).
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