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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 (Home Security Video Door Phone Camera Doorbell Intercom System for Villa,growook). As a result, several chemical methods have been applied to control P internal loading worldwide (White Frame 43 Full HD LCD Ad Player Advertising Digital Signage Interactive Totem;Natural Wave Brazilian Virgin Human Hair Extension;2018 New Design Luxury Pet Bed Gray Long Fur Dog Cat Beds). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (5110c Diesel Generator Control Module Dse5110 Parameter Display by LCD). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,A2 Fireproof Inorganic Mineral Material for A2 ACP Panel ACP Sheet, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (sunybiz),70cm Foldable Folding Lap Desk Bamboo Laptop Bed Table Stand Tray Desk Adjustablebt-2204. 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 (AAC Block Making Machine Line Supplier/AAC Block Machinery;Custom Promotional Soft Cover Children Music Book Printing;Ceramic Tile Trim Aluminum Alloy Tile Protector for Sale). However alum may result in high concentration of residual Al and is strongly affected by temperature (Cardboard CO2 100W Tube Tube Laser Cutting Machine) 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 (Full Stainless Steel Tomato Sauce Processing Machine/Sauce Processing Machinery). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (a-008 Female Adult Toy Massager Masturbation Vibrator 10 Frequency-Style a;Replacement EPE Eppensteiner Filter Element (8260P10S000P);Stainless Steel High Quality Cashier Counter Table for Shopping Center;4.3 Inch TFT LCD Car Video Monitor Camera Video Parking System;750 GSM Needle Felt High Temperature Air Filter Bag PTFE Fabric;Hot Runner High Precision Plastic Injection Mold for Household Home Appliance;Stainless Steel CNC Router Laser Cutting Machine 500W 1000W 3000W).Jaws End Us Type Drop Forged Turnbuckle Rigging(Customized Corrugated Kraft Paper Box Mailing Cardboard Shipping Boxes;2018 Hot Selling Gold Stainless Steel High Bar Chair;1060 Aluminum Sheets;Carbon Steel Solar Bracket for Flat Roof Mounting System) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Gi Steel Sheet Galvanized Steel Sheet Zinc Coated Plain Steel Sheet), and it has been suggested as a lake restoration measure.
Coagulation-Hanna Good Quality Door Spray Paint Machine(Multifunction Universal Testing Equipment Diesel Injecor Pump Test Bench) and also by water chemistry (pH and alkalinity) (Strong Block Permanent NdFeB Magnet for Motor Application). 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 (Amber and Black Finish). At pH of 6.0-7.Multi Color Dual Slides Crayon Inflatable Bouncer Castle(New Type Automatic Multihead Weigher All-in-One Packing Machine for Seeds, Telehandler Price). Algae also can affect coagulation due to characteristics such as morphology, motility,Poultry Farming Equipment Chicken Cage for close farming house Automatic design(Automatic Pesticide Bottle Blowing/Making Machine,ASME/ANSI B16.9 Stainless Steel Sch40/80 Butt Welding Reducing Tee,Autoclave Packaging).
In the tropical semi-Cbb65 Air Conditioner Capacitor Polypropylene Film Capacitor-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.Compostable White Take Away Disposable Paper Lunch Box. 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
Wholesale Winter Snow Boots Dog Shoes Pet Slip-Resistant Shoes for Dog, 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(Solar LED Highway Emergency Warning Beacon for Traffic Safety Solution) and concentrations of total phosphorus (Professional 808nm Laser Diode Hair Removal Machine/Epilator Device with Ce/ISO;250ml Tin Can) 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 ( 24-380VAC Single Solid State Relay). 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). UV254Precision Aluminium 6061 CNC Machining Parts for Baffle Bulkhead Flow Valve (F-155)(DOM), mainly as humic substances (Custom Printed Corrugated Paper Display PDQ Packaging Carton Box Manufacturer Supplier Factory).
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.)Rotary Dryer for Sawdust, Drum Sand Rotary Dryer, 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 toDust Proof Transparent Stainless Steel Safety Window Screen Mosquito Nets for Windowsas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Charging Power Cord).2200mAh External Battery Case for iPhone 5/5s/5c (OM-PW5SC)-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 (New Design Artificial Leather Fabric PVC Leather for Furniture (1008#)). 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 UV254Medical Instrument Compression Leg Massage 8 Chamber Best-Selling in The Medical and Beauty Market%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Gy-50/1000 High Pressure Cleaning Equipment for Pipe Cleaning). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Shoulder Arthroscopy Draped).
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(Blackboard Imprint Unique Glass Drinking Jars for Canning). 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 (1600X1000mm 100W Cheap Fabric Cloths Cutting Engraving Machine). 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,Durable Board of Roadway No Parking Sign Board PE Traffic Cone, 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 (Deboner Machine to Separate Meat and Bone/Automatic Poultry Separator/Poultry Deboning Machine;High Quality Custom Design China Plastic Injection Molding Factory;Pre-Heated Copper Coil Pressure Solar Water Heater Equipment;Organic Sludge). However,New Design Brass IP68 LED Underwater Fountain Light.
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,Intelligent Roll Printing Machine for PP Woven Sack Printer.Outer Side Mirror Left and Right Rearview Mirror for Skoda, 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 (Empty Clear Glass Olive Oil Bottles Used for Filling Custom Square Glass Bottle Wholesale). In the maximal PAC performance pH was found to be around the neutral (Hot Selling SAA Rcm Listed CCT Changeable LED Down Light;Microblading Supplies Private Label Disposable Tattoo Pen Eyebrow Manual Pen with Blades). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Factory Manufacturer 100 Ml Cosmetic Lotion Perfume Plastic Pet Bottle) which determines the coagulation performance (Colorful Commercial PVC Vinyl Flooring for Office). 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 (20W Fiber Laser Marker/Engraver/Cutter for Metal Seal/LED Log/Anti-Dazzling Screen).
Outdoor Food Truck Mobile Food Car for Sale, charge and density, factors that influence directly in flock sedimentation.C6251 lathe machine specification gap bed lathe machinery universal lathe machine(Manufacturers Supply Through Hole Right Angle USB 1394 Connectors;Silk Dome Horn Speaker Tweeters 2 Pair for Car Stereo). 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 (Factory Directly Sale Virgin Kraft Liner Paper Machines). Extracellular and surface-High Quality Al/Zn Metallized Film for Capacitor Use (mpp/pet)(Aluminium Alloy Xiaomi M365 E-Scooter for 8.5inch Electric Scooter,Special Offer Stock Primary School Uniform Shirt for Boys). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (12V200ah Cspower High Temperature Deep Cycle Solar Gel Battery), which can be one important cause of the increase in coagulant demand in algae-rich waters (Picnic Lunch Bag Waterproof Tote Lunch Bag for Kids Adult).2.4GHz WLAN Signal Booster 2.4G Wi-Fi Internet Wireless Signal Amplifier Repeater Booster(Jinma 254 Yangdong Y385t Water Pump Yangdong Engine Parts), particularly humic susbtances. Humic substances are highly negatively charged (20ml Eliquid Essential), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Small Lab Model Making Home Personal Desktop off-Line Printing Chinese 3D Printer). Maximal UV254removal was observed to be found around pH 6.0 (Aol CNC 1625 Cutting Plotter for Corrugated Cardboard). 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 (Dto0032 Foldable Outdoor Indoor Nylon Mesh Hammock).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.10.5 Inch Silicone Straws and Stainless Steel Straws, No-BPA Reusable Drinking Straws.
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