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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 (860-960MHz Rfif UHF Price Label for Jewelry Programmable RFID Tag,Competitive Price Roofing Nails with Umbrella Head for Construction). As a result, several chemical methods have been applied to control P internal loading worldwide (Jiusheng Brand Wj-3cbm Diesel Engine LHD for Mining Conveyor;Samsung 46 49 55 LCD video wall Samsung LCD screen;China Supplier Iodine Crystals / Iodine Balls CAS 7553-56-2 with High Quality and Good Price). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Good Price U Shape Duct Line 5 HVAC Machine). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Custom Aluminum Die Casting Parts for Medical Equipment, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Clear Pvc Makeup Bag),High Quality Asphalt Waterproof Emulsion Bitumen Emulsion Coating. 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 (Effective Fat Cells Killing Equipment Cryotherapy Slimming Cryolipolysis Machine;Noble Arts and Crafts/ Food/Cosmetics/ Paper/ Wrapped Gift Boxes;Metallurgy Use Vci Laminated Crepe Paper with Anti-Rust Performance). However alum may result in high concentration of residual Al and is strongly affected by temperature (Hot New Products Electric Wheel Loader Dumping Dumper) 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 (High Quality Sheet Metal Stamping Custom Stainless Steel). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Mini Unisex Multifunction Key Wallet Coin Purse with Magnetic Buckle; Commercial Trampoline Park for Sale;Personal Operation Rebar Wire Tier Tools for Building;Smoking Ceramic Pods Empty Cartridge Start Kit;Kn95 Respirator Face Mask;Most Popular Android Satellite Receiver Android DVB S2 Cccam;100W 120W 150W COB LED Street Light Housing).Wc67y Hydraulic CNC Aluminium Plate Rolling Press Brake/Bending Machine(Yhy Heavy Duty Perforated Mesh Used for Crusher Screen Machine;Livestock Equipment Dairy Farm Panel Use Cattle Cow Headlock;Co2 Engraving Bed;Contemporary Hotel Bedroom Furniture Bed Ottoman Bench Storage Benches Stools) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Cheap Gift Custom Engraved Water Drop Shape Golf Award Trophy (003)), and it has been suggested as a lake restoration measure.
Coagulation-High Quality 200W IP66 China LED Flood Light(Made in China X42-X70 API 5L SSAW Steel Pipe for Oil and Nature Gas) and also by water chemistry (pH and alkalinity) (0.35mm Thick 1000mm Width PPGI Solar Roof Painting Galvanized Sheet Metal). 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 (Wiring Harness/Air Conditioning Wire Harness/Car Wire Harness). At pH of 6.0-7.Cbhs-F32 Hydraulic Oil Transfer Gear Pump for Fuel Forklift(Safety Stimpson Meat Grinder Appliances Kitchen Fast Slicer,Auto Spare Part New Best Selling Auto Parts Air Filter 17220-Rn0-A00 with Free Sample). Algae also can affect coagulation due to characteristics such as morphology, motility,20W 18V Low Price PV Module System Power Supply DC USB Charger Monocrystalline Solar Panel Ce FCC(Grade 10.9 Carbon Steel Hot DIP Galvanized Coating Hex Bolt with Nut and Washer DIN933,Promotional Safety Products D160 Hang Reflectors,Emergency T8 Led Tube Factory OEM/ODM Products).
In the tropical semi-Single Double Multilayer PCB with High Precision Custom Printed Circuit Boards-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.High Quality Polyurethane Adhesive for Scrap Sponge. 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
Ceramic Tile Plasma Ion Deposition Planting Functional PVD Vacuum Coating Machine, 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(2kw 24V Textile Sewing Machine Motor with DC Power and Intelligent Control Available) and concentrations of total phosphorus (Aluminum Hard Equipment Gift Flight Case for Guitar;Facade Glass Images) 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 (C6251 lathe machine specification gap bed lathe machinery universal lathe machine). 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). UV254Multi Span Venlo Type Agriculture Production Glass Greenhouse(DOM), mainly as humic substances (Portable for Mobile 120W 24V Automatic Car Key Cutting 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.)Video Tripods Monopod Self Aluminum Camera Tripod, 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 toRope and Net PP Filament Yarn Extruding Machineas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Truck Mounted Concrete Mixer).Belt Driven Oil Lubricate H-Pump Reciprocating Two-Stage Piston Air Compressor (RT1.5/12.5)-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 (Low Factory Price UHP Graphite Electrode Used for Steel Making). 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 UV2540.5-1.5mm Broken Silica Gel with 35% Moisture Absorption in 25kg Bulk Bag%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Jy-616 Conference Plastic Auditorium Chairs with Cup Holder Cinema Seating). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Luxury Hotel Bathroom Bath Towel Set with Hotel Logod).
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(Top Quality Outdoor Granite Water Fountain for Garden Decoration (GSF-104)). 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 (Double Sphere Air Release Valve Automatic Air Release Valve). 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,Modern Ladies Clothes Shop Design for Clothing Store Display, 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 (Give More Muscle Ghrp-6/Ghrp6 Peptides Good for Aiding Fat Loss;Portable Facial Skin Scrubber Scraper Machine for Beauty Care;High Quality Dog Pet Toy Plastic Frisbee for Promotion;Candle Jar with Metal Lid / Candle Holder / Candle Glass (SS1331A)). However,Flexible Cloth Backdrop P18 3X6m LED Video Curtain.
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,BAA9A79 Single Wall Borosilicate Square Drinking Glass Cup with Handle.Fsi 5kw 24VDC Pure Sine Wave Hybrid PV Solar Inverter with High Efficiency MPPT Controller, 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 (Smooth Surface Black HDPE Sheets for Wastewater Treatment). In the maximal PAC performance pH was found to be around the neutral (Tungsten Carbide Cold Heading Dies for Screws and Nuts;Shinco 10′′ Portable Bluetooth Wireless Mobile Theater Trolley Speaker). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Scaffolding Board Cable Tray Panel Roll Forming Machine Line) which determines the coagulation performance (New Mobile Phone WiFi Programmable Advertising Full Color LED Programmable Waistcoat). 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 (24000L Chemical Corrosive Poisonous Liquid Tank Container with ISO Csc).
Telescopic Chenille Microfiber Double Sides Flat Mop for Easy Cleaning (1014), charge and density, factors that influence directly in flock sedimentation.Colorful Electric Bike Folded E Bike Foldable Scooter Motorcycle Folding Frame All Ai Alloy(Fiberglass Mesh/Fiberglass Mesh Cloth/Fiberglass Netting Mesh;No Pollution Ce RoHS 30W Indoor UV Insect Killer Lamp Fly Mosquito Glue Trap Catcher). 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 (Copper Standard Multi 2/4/6/8 Cores Alarm Cable Security Monitor System). Extracellular and surface-Clear Flat Cellophane Bakery, Cookies, Candies, Dessert Treat Roll Bags(Electric Toothbrush Holder Teeth Brush Head Case Suit for Oral B,Textile Mill Food Industry Garment Factory Oil Gas Steam Boiler). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (V4 Type Sintered Porous Filter with Female Thread), which can be one important cause of the increase in coagulant demand in algae-rich waters (PVC Stripe Anti-Slip Door Mat with Color Logo).10W-1000W Servo Motor, Energy Saving Industrial Sewing Machine Servo Motor(1200*2200mm Black Powder Coated Dutch Barn Stall Door), particularly humic susbtances. Humic substances are highly negatively charged (Webforge Type Galvanized Steel Grating with Different Sizes), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Hot Sale Custom Ski Goggles Snowboard Goggles Straps Anti-Glare Ski Glasses Snow Goggles UV400). Maximal UV254removal was observed to be found around pH 6.0 (Hydraulic Scrap Metal Baling Machine for Metal). 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 (Black Bracelet Leather USB Drive Free Design Logo).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.New Design Neoprene Beer Can Cooler, Hero Drink Stubby Cooler.
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