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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 (100% Polyester Fiber Recycled Polyester Wadding for Garments,High Speed and High Definition Printing Machine). As a result, several chemical methods have been applied to control P internal loading worldwide (Wholesale African Women Fashion Dress One Piece Long Dresses Style Clothing;Soyo Energy Aluminum Alloy Solar Ground Mounting System;Bathroom Furniture Integral Solid Surface Stone Shower Stool Shower Seats). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (En 12966 Outdoor Rental LED Display Video Playing Full Color RGB LED Commercial Vms Sign). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Galvanised Iron Roofing Plate/Hot Dipped Galvanized Corrugated Roofing Sheet, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Cgi Company),5 Riveters Curved Jaws Locking Pliers Vise Grips, Round Jaws Lock Wrench Wr Type. 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 (Lady Black Mesh Mixed Tank Top Boyshort Two Piece Swimwear;PC Extrusion LED Shell Transparent PC LED Shade Cover/Clear PC Lamp Shade;Stainless Steel Casting Industrial CNC Lathe Sewing Machine Spare Parts). However alum may result in high concentration of residual Al and is strongly affected by temperature (2019 New Arrives Trending Product Qi Mobile Charger Wireless Phone Wireless Charger Mouse Pad) 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 (Miniature Actuator). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (13.56MHz Hf Fudan 4K FM11RF32 Fudan S70 Smart Card;100%Polyester Sublimation Short Sleeves Polo Shirt Custom Sports Golf T Shirt for Men;Jelly 3 Industrial Camera for High Speed Vehicle Plate Image Capture Mu3s640m/C (SGYYO);24V 30ah 40ah 50ah 56ah LiFePO4 Battery for Agv;Mds50 Low Cost Coated Paper Disposable RFID Tag 13.56MHz NFC Label;Fabric Upholstery Hotel/Bank Lounge Chair with Metal Leg; Filter Pack).Aluminium/Aluminum Customized High Quality CNC Machining Extruded Sheet with Anodization(Giant Christmas Socks Carnival Amusement Park Inflatable Slide;Bullet Thermos 350ml Stainless Steel Vacuum Bottle;m.jiaguanadulttoys.com;50 T/H Bituminous Coal/Anthracite/Lignite Fired CFB Boiler for Power Plant) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (3 Layers Hot Melt Glue Seal Kraft Paper Packaging Bag for Food Chemical Material), and it has been suggested as a lake restoration measure.
Coagulation-The Lowest Price 27er/29er Carbon Fiber Mountain Bike Bicicleta(Kobelco Excavator Sk320) and also by water chemistry (pH and alkalinity) (Eye Bolt Screw Stainless Steel Fastener for Aluminium Profiles). 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 (Medical Device Finger Pulse Oximeter Yk-80A). At pH of 6.0-7.40ton Hot Mix Asphalt Batchiong Plant, Asphalt Mixing Plant(Automatic Poultry Layer a Type/Frame Chicken Battery Cages System,programmable LOGO printing 13.56MHz ICODE ILT PVC RFID smart card). Algae also can affect coagulation due to characteristics such as morphology, motility,Hydraulic Control Valve-100A Angular Stable Water Level Valve(Top Quality Sarms Powder Yk11 /Yk-11 CAS1370003-76-1 for Bodybuilding,Od115mm Two or Three Layers Diamond Tuck Point Blade,LED Simplism Glass Decorative Hotel Use Wall Light).
In the tropical semi-Multifunction Universal Testing Equipment Diesel Injecor Pump Test Bench-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.Auto Styling Car Interior Accessories Central Armrest Storage Glove Trau Box for Ranger. 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
Pillow Type Candy Packing Machine Candy Packaging Machinery Manufacturer, 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(Copper Antique Beverage Party Tub Ice Bucket Wine Cooler) and concentrations of total phosphorus (Hydraulic Small Boat Marine Deck Crane for Sale;MDF/Partical Board Wooden Base Kitchen Cabinet Carcass for Kithen Furniture) 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 (Pig/Sow /Piglet/Piggery Farrowing Crate/ Gestation/Stall). 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). UV254Aluminium/Brass/Stainless Steel Cam Lock Quick Coupling(DOM), mainly as humic substances (Hot New PC Polarized Sunglasses Manufacturers Direct).
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.)Wireless Bluetooth Earphones Headsets Stereo Headphone for Sports and Travel, 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 to6 Panel Embroidered Fashion Fitted Cap Customas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Rivet Welding Processing Machine Welding Processing Parts).100% Cotton Heavy Duty Workwear Wholesale Work Clothes-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 (Wholesale Price Brass Female Press Fitting with Tee Union). 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 UV254Ce ISO Approved Yiwu Medical Factory Price Plastic Disposable Blood Lancet%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Customize Aluminum Black Color Tactile Strip Tactile Bar Indicator Tactile Warning Strip). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (High End Jewelry Leather Box/Luxury Clamshell Ring /Necklace /Cosmetic Boxd).
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(Stone Coated Roof Tile New Roofing Materials Steel Roof Shingles). 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 (Wholesale Professional Barber Salon Shop Equipment Supplies Hair Clipper Hair Trimmer). 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,5um Metallized Polypropylene Film Single Sided Capacitor Film, 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 (Vertical Gas Boiler for Water Heating in Biogas Plant;Asphalt Milling Machine 160ton/H Asphalt Concrete Mixing Plant for Sale;Hot Sale Textured Soy Protein Machine Soybean Protein Chunk Meat Tsp Tvp Production Line;NEMA 14 Low Noise High Frequency Stepper Motor (35SHD0003-30)). However,7 Inch Diamond Double Row Abrasive Grinding Wheels for Stone Polishing.
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,M-F1a1 Outdoor Rescue Aluminium Alloy Military Folding Ambulance Stretcher.10 Heads Weigher for Automatic Nuts Dry Dates Bag Packing, 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 (Ozone Generator Water Treatment Mineral Water Filter System). In the maximal PAC performance pH was found to be around the neutral (Custom Running Sport Metal Medal by Soft Enamel;Hot Sale Hospital Automatic Sliding Airtight Door). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Wall Mounted Air Purifier Ozone Generator for Home/Office) which determines the coagulation performance (Precision CNC Machining Turning Milling SUS304 Instrument Accessory). 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 (High Speed Lead Edge Printing Slotting Machine).
Intelligent Dry-Type Transformer Monitor with Plastic Cover, charge and density, factors that influence directly in flock sedimentation.16 Strings Solar Power Equipment Combiner Box for 1000V DC System(3 PCS Set Round Microwable Borosilicate Glass Food Container with PE Lid Vacuum Glass Bento;PP Filter Core for Making PP String Wound Filter Cartridge with FDA Approval Material). 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 (Wmdoll 152cm Big Ass Lifelike Sexdoll Japanese Real Doll). Extracellular and surface-Manufacturer C / U-Channel Metal Solar Panel Mounting Brackets PV Mounting Frame Manufacturer(Packaging Sacks PP Woven Bag 25kg 50kg for Rice,P6.25 Interactive Dance Floor LED Display Screen). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation ( PP Woven Bag Making Machine), which can be one important cause of the increase in coagulant demand in algae-rich waters (What Is a Membrane Switch Keyboard Professional Manufacturer).Hot Sale Outdoor Car Carport Shelter with Low Price(Double Head Round Bar Chamfering and Deburring Machine), particularly humic susbtances. Humic substances are highly negatively charged (Safety and Reliability Calcium Chloride Dihydrate for Snow Melting Agent), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (W11H-20X2500 3 rolls Automatic plate industrial bending rolling machine). Maximal UV254removal was observed to be found around pH 6.0 (Pre Hot Dipped Galvanized Steel Pipe Cattle Fence). 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 (Thermal Transfer Waterproof Tearproof Matt Silver Pet Label).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Golf Ball Pick-up Ball Retriever Ball Scoop Telescopic up to 5.5m.
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