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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 (Customized Corrugated Kraft Paper Box Mailing Cardboard Shipping Boxes,Kitchen Gadget Stainless Steel Pizza Knife/Circular Roller Pie Cutter). As a result, several chemical methods have been applied to control P internal loading worldwide (2018 Hot Selling Gold Stainless Steel High Bar Chair;Carbon Steel Solar Bracket for Flat Roof Mounting System;Gi Steel Sheet Galvanized Steel Sheet Zinc Coated Plain Steel Sheet). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Multifunction Universal Testing Equipment Diesel Injecor Pump Test Bench). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,80kw Electric Canopy Diesel Generator Powered by Cummins with Ce/ISO, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Tianyu Metal Door Frame Cold Roll Forming Machine),Luxury Brand L-V Genuine Leather Wallet and Genuine Leather Card-Holder. 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 (Strong Block Permanent NdFeB Magnet for Motor Application;New Type Automatic Multihead Weigher All-in-One Packing Machine for Seeds; Telehandler Price). However alum may result in high concentration of residual Al and is strongly affected by temperature (Automatic Pesticide Bottle Blowing/Making 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 (Rollers For Track). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (ASME/ANSI B16.9 Stainless Steel Sch40/80 Butt Welding Reducing Tee;China Factory Processing Auto Car Accessory Motor Computer Part by CNC Machining;High Quality Aluminum Alloy Sand Casting Gravity Casting Aluminum Parts;Solar LED Highway Emergency Warning Beacon for Traffic Safety Solution;Bonding Strength Testing Machine Servo Control Universal Tensile Strength Tester;Professional 808nm Laser Diode Hair Removal Machine/Epilator Device with Ce/ISO;Youthful Nylon Waterproof School Backpack).New Arrival Sports Anti UV Protective Arm Sleeves(2000kg/H Automatic Onion Chopper Slicer Slicing Cutting Processing Machine; 24-380VAC Single Solid State Relay;m.suase-plastic-mould.com;Custom Printed Corrugated Paper Display PDQ Packaging Carton Box Manufacturer Supplier Factory) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Used Tire Reclaimed Rubber Machine / Rubber Sheet Making Machine), and it has been suggested as a lake restoration measure.
Coagulation-Automatic Poultry Layer a Type/Frame Chicken Battery Cages System(Black Velvet Fabric Dining Chair Gold Frame Brass Metal Legs Tub Chair) and also by water chemistry (pH and alkalinity) (Comfortable Pillow Top Latex Pocket Spring Coil Hotel Mattress). 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 (15kv Metal Oxide Ploymeric Housing Surge Protector Lightning Rod Arrester). At pH of 6.0-7.Round Vibrating Separator Machine - Round Vibratory Sieve(Dust Proof Transparent Stainless Steel Safety Window Screen Mosquito Nets for Windows,Shockwave Therapy Machine Shock Wave Physiotherapy Equipment Air Pressure Shockwave Sw10). Algae also can affect coagulation due to characteristics such as morphology, motility,High Strength PVC Foam Board for Building Materials(Steel Toe Cap Men Leather Safety Shoes Footwear Ufe019,New Design Artificial Leather Fabric PVC Leather for Furniture (1008#),Anvil Air Compressor Supplier).
In the tropical semi-Factory Wholesale Pillow Low Price Polyester Microfiber Down Alternative Cushion-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.Denim Molile Phone Accessories USB Data Charging Lightning Cable for Type-C. 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
Hydraulic Metal Chips Block Moulding 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(Blackboard Imprint Unique Glass Drinking Jars for Canning) and concentrations of total phosphorus (1600X1000mm 100W Cheap Fabric Cloths Cutting Engraving Machine;100kw AC Three Phase Silent Portable Electric Diesel Generator) 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 (Deboner Machine to Separate Meat and Bone/Automatic Poultry Separator/Poultry Deboning 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). UV254Aluminum/Cooper/Galvanized Tube Precision Pipe Making Machine(DOM), mainly as humic substances (High Quality Custom Design China Plastic Injection Molding 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.)Natural Light Green/Beige/Pink Slate Thin Cut Surface Culture Stone, 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 toMicroblading Supplies Private Label Disposable Tattoo Pen Eyebrow Manual Pen with Bladesas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Gold Hyaluron Pen Needle Free Hyaluronic Injection Lip Lifting Wrinkle Removal).S23 Electric Logistic Car, Cargo Box, Cargo Van, Cargo Container, Cargo Pickup, Closed Logistics Vehicle-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 (Manufacturers Supply Through Hole Right Angle USB 1394 Connectors). 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 UV254Na2co3 Soda Ash Sodium Carbonate Food Grade%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Silk Dome Horn Speaker Tweeters 2 Pair for Car Stereo). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (500ml Amber Empty Glass Wine Bottle with Capd).
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(Special Offer Stock Primary School Uniform Shirt for Boys). 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 (12V200ah Cspower High Temperature Deep Cycle Solar Gel Battery). 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,Water Jet Cutting Machine Spare Parts Waterjet 3/8 High Pressure Pipe, 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 (Small Lab Model Making Home Personal Desktop off-Line Printing Chinese 3D Printer;Aol CNC 1625 Cutting Plotter for Corrugated Cardboard;Dto0032 Foldable Outdoor Indoor Nylon Mesh Hammock;Scrubber). However,Building Material Steel Coil Zinc Coated Prepainted Galvanized Steel Coil.
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,Three-Way Car Horn Air Compressor 12V 24V.Stainless Steel Electric Heating Mixing Kettle for Food Industry, 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 (Beautiful Christmas Printed Gift Polyester Grosgrain Ribbon Satin Ribbon). In the maximal PAC performance pH was found to be around the neutral (Custom Stand up Composite Material Zipper Packaging Bag Candy Bag;New Model Solar Room Lighting System Lighting Kit Light in Remote Area). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Lacquered PVC High Intensity and Good Elastibity Tarpaulin) which determines the coagulation performance (Plastic Packing Film Roll). 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 (Factory Wholesale T5 T6 7075 6061 6063 Alloy Aluminium/Aluminum Sheet Plate).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Kw-700 Industrial Commerical Driving Type Floor Scrubber Price.
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