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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 (Stainless Steel Welded Woven Metal Wire Mesh Basket for Filter,Military Sweater). As a result, several chemical methods have been applied to control P internal loading worldwide (Factory Price Luxury Autism Heavy Duty Weighted Mink Blanket;Household Thermometer Electronic Temperature and Humidity Meter Monitor;4.5qt Camping Nonstick Wholesale Cast Iron Dutch Oven Bread Pan). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Tractor Trailer Cable Truck 7 Core Spiral Coiled Electric Cable for Tractor & Trailer). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Air Bubble Stone as Ozone Diffuser for Air Pump, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Flexo 1-4 Color Water Ink Printing Slotting Die-Cutting and Stacking Machine),Solar PV Detached 30W 12inch Roof Mount Solar Ventilation Attic Vent (SN2014003). 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 (9000-12000 BTU Air Conditioning /Cabinet Air Conditioner for Marine;Twist Lock Power Cord;Hyaluronic Acid Gel Microneedling Device for Meso Serum Mesotherapy Solution). However alum may result in high concentration of residual Al and is strongly affected by temperature (Indoor HD LED Sign Board for Advertising LED Display Screen) 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 (www.mybarberchairs.com). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Automatic Packaging Filling Machine for Concentrated Liquid Detergent Pod; with Windproof;Food Grade Biodegradable Stand up Pouch Kraft Paper Packaging Bag with Zipper;Manufacture Tempered Glass Door Stainless Steel Curved Bottom Patch Fitting;Hot-DIP Galvanized Low Carbon Steel Wire Gabion Box;New Design Hot DIP Galvanized Pig Gestation Stall;High-Class Leather Cover Business Agenda Organizer Planner Notebook).Purity Veterinary Pharma Grade Albendazole with Competitive Price(High Strength PVC Foam Board for Building Materials;Custom Foldable Storage Basket with Metal Handle and Lid;316l Bright Annealed Tubing;Customized Normal Temperature Feed Channel Cylinder for Stacker Reclaimer) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Professional Mechanism Hydraulic Oil Headrest for Barber Chair), and it has been suggested as a lake restoration measure.
Coagulation-Trailer Part Coupling, ISO 7241A Quick Release Coupling Qrc 1/2′′npt(Terex Cone Crusher Spare Parts Concave Mantle and Bowl Liner) and also by water chemistry (pH and alkalinity) (Adjustable Folding Infant Feeding Baby Highchair). 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 (High Precision Customized CNC Lathe Ball Screw End Supports Parts). At pH of 6.0-7.Black PU Auto Car Neck Rest Car Seat Headrest Neck Pillow(THK Misumi Hiwin Linear Ball Bearing Block Bearing Gl25ca,Disc Neodymium N35 N45 N40 N42 N38 N48 N52). Algae also can affect coagulation due to characteristics such as morphology, motility,Receipt Book/Invoice Book/Business Form Book(Factory Price 304 304L 316 316L 321 Inox Stainless Steel Coil / Sheet / Plate,Double Sided Heat Tape for Electrical Adhesive Masking Packing Tape,Personalized 3 Piece ABS PC Travelling Bags Luggage Trolley Case Sets).
In the tropical semi-Best Price Lifting Face Body Shaping Portable Anti Cellulite Laser Machine-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.Comfortable and Soft Cat Pet Bed Pet Supplies Mini House for Cat. 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
Standard Vertical Rotary Automated Smart Tower Car Parking System, 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(Factory Ultrasonic Herb Solvent Extraction Equipment with Discount) and concentrations of total phosphorus (Dual 2 Cubic Meters Precast Concrete Mixer Batching Plant Machinery Manufacturer;Wooden Design Waterproof Vinyl PVC Plank with Click) 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 (High Quality Genuine Leather Luxury Casual Shoes Sneaker for Men Fashion Sneaker Shoes for Men). 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). UV254Stainless Steel Water Filter Housing RO Systems(DOM), mainly as humic substances ( Clear Textured Slip Resistant Strips).
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.)Vertical Automatic Computer Control Roll Slitting Rewinding Machine for BOPP, 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 toLong Range RFID Access Control Card for Non-Stop Parkingas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Bamboo Fiber Integrated Wall Panel).Custom Wall Hanging Flower & Plant Plastic Garden/ Nursery Pots-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 (ASTM A335 P11 Seamless Ferritic Alloy-Steel Pipe for High-Temperature Service). 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 UV254PVC Shrink Sleeve for Glass Bottle Capsule, Shrink Wine Cap%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Stainless Steel Galvanized Perforated Metal Sheets). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Hex Head Drilling Screwd).
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(Water Play Equipment Inflatable Gym Air Track Mat). 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 (50 Bend PVC Pipe/Belling PVC Pipe/Making 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,Adhesive Cut Table Heat Press PU Flex Vinyl/Film for T-Shirt, 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 (Colorful Glass Straw Drinking Straw Reusable Borosilicate Glass;Silicon Carbide Mechanical Seal with Excellent Corrosion Resistance;Hot High Quality Self Service Car Wash Equipment;Most Popular Lost Foam Casting Equipment Foundry). However,Yahsi Super Narrow Bezel 55 Full Color HD LCD Video Wall with Splicing LCD Screen.
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,Textile Machine Parts Multiple Pattern Box.2020 Sale Stuffed Meatball Processing Meat Ball Making Machinery, 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 (Pedstal Electric Stand Fan 5 Speed Control Air Cooler). In the maximal PAC performance pH was found to be around the neutral (Manufacturers Sell Direct Bullet Design Red Hollow Crown Lipstick Tube;High Quality Asphalt Waterproof Emulsion Bitumen Emulsion Coating). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Fashion Watch Factory Swiss Quartz Women Wrist Branded Watch (WY-001H)) which determines the coagulation performance (www.gsbracefactory.com). 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 (Commercial Industrial Fast Food Chicken Electric Gas Pressure Deep Fryer for Mijiagao).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Top Quality Model Tqlq Series Combined Paddy Cleaner for Rice Processing Plant.
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