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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 (Hydraulic Small Boat Marine Deck Crane for Sale,6 Vertical Aligned Spindles Independent Sleeves CNC Boring Heads). As a result, several chemical methods have been applied to control P internal loading worldwide (Food Processing Industry Fruit Vegetable Drying Machine;Printing Paper Coated Art Paper C2s/C1s Gloss/Matt Art Printing Paper;Pig/Sow /Piglet/Piggery Farrowing Crate/ Gestation/Stall). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Hot New PC Polarized Sunglasses Manufacturers Direct). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Rectangle Custom Various Color Metal Label Tag Sticker Handbag/Luggage Hardware, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Screw Type Waterproof Flat Plug Long Power Plug),Full Car Key for Chrysler 5+1 Button Remote Control. 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 (High Precision Durable Aluminum Cutting Saw Blade;Blocking-Concealed Passport Holder RFID Wallet with Neck Strap;2019 Hot Sale Air Cooling Laser Wafer Dicing Equipment). However alum may result in high concentration of residual Al and is strongly affected by temperature (6 Panel Embroidered Fashion Fitted Cap Custom) 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 (6304 2rs). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Harem Sweat Sport Casual Women Pants for Jogger;Stupid Cow Indoor Coin Operated Arcade Video Vending Simulator Shooting Game Machine;Wholesale Price Brass Female Press Fitting with Tee Union;Customize Aluminum Black Color Tactile Strip Tactile Bar Indicator Tactile Warning Strip;m.anebon.com;Poultry Farm Equipment Feeding System Made in China;Stone Coated Roof Tile New Roofing Materials Steel Roof Shingles).WiFi Outdoor Security CCTV Battery Solar Powered Wireless IP Camera(Wholesale Professional Barber Salon Shop Equipment Supplies Hair Clipper Hair Trimmer;High Quality Five Bars Checker Nr/SBR EPDM Cr Black Rubber Rolls Flooring Mat;Hand Held Cement Vibratory Concrete Vibrator 2840rpm;Delight 15W Sensor+Night Sensor Solar Garden Lamp) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Vertical Gas Boiler for Water Heating in Biogas Plant), and it has been suggested as a lake restoration measure.
Coagulation-Crystal or Plastic Pendant Lamp, DIY Shade (WHP-453)(Asphalt Milling Machine 160ton/H Asphalt Concrete Mixing Plant for Sale) and also by water chemistry (pH and alkalinity) (Hot Sale Textured Soy Protein Machine Soybean Protein Chunk Meat Tsp Tvp Production Line). 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 (m.outdoorgamefactory.com). At pH of 6.0-7.Microfiber Cleaning Cloth Towel Waffle Towel Tea Towel(Ozone Generator Water Treatment Mineral Water Filter System,Custom Running Sport Metal Medal by Soft Enamel). Algae also can affect coagulation due to characteristics such as morphology, motility,NEMA IP65 Wall Mount Electric Metal Cabinets(Hot Sale Hospital Automatic Sliding Airtight Door,Wall Mounted Air Purifier Ozone Generator for Home/Office,Best Laser Opt Shr Electric Permanent Hair Removal Machine).
In the tropical semi-11mm Neck Crimp Cap Vials with Patch, Cap Septem-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.Pet Factory Wholesale Black Climbing Wooden Cat Tree (YS98797). 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
Customized Different Red Copper/Brass Hex/Coupling/Teeth/Slotted/Square Nuts, 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(PP Filter Core for Making PP String Wound Filter Cartridge with FDA Approval Material) and concentrations of total phosphorus (Wmdoll 152cm Big Ass Lifelike Sexdoll Japanese Real Doll;High Quality Decamethylcyclopentasiloxane/Oil D5 with Best Price 541-02-6) 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 (What Is a Membrane Switch Keyboard Professional Manufacturer). 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). UV25410.1 LCD Module 1024*600 Optional Touch Panel for Medical Equipment(DOM), mainly as humic substances (Double Head Round Bar Chamfering and Deburring Machine).
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.)Solid Surface Grade Grinding Alumina Tyihydrate, 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 toModern Leisure Chair for Europeas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Business Paper Card).Stranded Loose Tube Armoured Direct Buried Underground Optical Fiber Cable-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 (Modern Living Room Wood Frame Genuine Bonded Leather Chesterfield Sofa). 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 UV254Speed Reducer Gear Parts Aluminum Die Casting Parts for Auto Spare Parts China%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (New Baking Tool Creative Customized Silicone Toast Cake Mold). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (China Solar Panels Custom Maded).
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(Littlefuse IC Fuse Cartridge Ceramic Electronic Component Nanosmdc012f-2). 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 ( AC4900ca). 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,Desktop Fiber Laser Cutter 1390 Cheap Price 800W/1000W, 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 (Steel Drilling Water Well Filter / Bridge Slot Screen Pipe;Astma312 TP304/Uns30400/X5crni18-10 Seamless Stainless Steel Round Hollow Bars;C-Type 2 Piece Tin Can Making Punch Press Machine;Outdoor Flood Light Stadium Sport Court Field Parking Lot 100W LED Flood Light). However,LED Lens 3030 5630 Asymmetric Linear Fresnel Acrylic PMMA Lens.
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,Double Station Pesticide HDPE Bottle Making Machine.Intelligent Screw Packing Machine for Lighting Bathroom Hardware Screw Accessories, 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 (Biobase -10~-25 Degree Upright Style Single Door Lab Deep Freezer). In the maximal PAC performance pH was found to be around the neutral (Powerful Bass and Nosie Cancelling Over Ear PS4 Gaming Headphone with Mic/Mute and Volume Control;Custom Ductile Iron Casting Parts Gray Iron Sand Casting). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (High Quality Sand Paper for Sand Machine Brush (YY-170)) which determines the coagulation performance (100DXD). 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 (Portable Trade Show Stand Tension Fabric Event Backdrop Display Stand From Tianyu).
Hydraulic Valves-Yuken Series Valve-Flow Control Valve- (one-way) Throttle, charge and density, factors that influence directly in flock sedimentation.High Energy Ejector Venturi Gas Scrubber System(Engineering Plastic Material;SAE 100 R1 R2 1sn 2sn Hydraulic Hose Assembly Fittings). 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 (GMP Certified Collagen Softgel for Fish Collagen). Extracellular and surface-PVC Coated /Zinc Coated /Plastic Spray Chain Link Fence(Clear Plastic Membership Gift ID Magnetic Forsted PVC Card,26000lm 200W LED High Bay Lamp Fixture for Gym House Factory). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Luzhong-700 70HP 2WD Two Wheel Drive Farm Tractor), which can be one important cause of the increase in coagulant demand in algae-rich waters (Hjd-J3 Double-Position Semi-Automatic Heat Transfer Machine).6.2mmx6.2mmx4.3mm SMD Waterproof Tact Switch(Corn Starch Foam Biodegradable Frozen Food Packaging Tray), particularly humic susbtances. Humic substances are highly negatively charged (Rfid Credit Card Protector), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Good Quality of 60t/D Wheat Flour Milling Plant). Maximal UV254removal was observed to be found around pH 6.0 (Energy Saving One Step Automatic Tritan Pet Blow Molding Machine). 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 (Bailian F Customized Server 2019 Hot Sell IPTV Server).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Spdt Floating Valve Motorized Zone Valve for Water Pressure Regulator.
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