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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 (Indoor HD LED Sign Board for Advertising LED Display Screen,Waterproof Straight Male Female Sensor Connector). As a result, several chemical methods have been applied to control P internal loading worldwide (Automatic Packaging Filling Machine for Concentrated Liquid Detergent Pod; with Windproof;Food Grade Biodegradable Stand up Pouch Kraft Paper Packaging Bag with Zipper). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Manufacture Tempered Glass Door Stainless Steel Curved Bottom Patch Fitting). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Injection Product Mold Factory Plastic Injection Molding Factories, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Stainless Steel Water Pump),Kaishan YT23D Forging Air Leg Support Rock Drill Machine. 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 (New Design Hot DIP Galvanized Pig Gestation Stall;High-Class Leather Cover Business Agenda Organizer Planner Notebook;High Strength PVC Foam Board for Building Materials). However alum may result in high concentration of residual Al and is strongly affected by temperature (Custom Foldable Storage Basket with Metal Handle and Lid) 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 (Imee Printing Promotion Custom Diary Leather Cover Notebook). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Customized Normal Temperature Feed Channel Cylinder for Stacker Reclaimer;Professional Mechanism Hydraulic Oil Headrest for Barber Chair;Terex Cone Crusher Spare Parts Concave Mantle and Bowl Liner;Adjustable Folding Infant Feeding Baby Highchair;4G/WiFi/Bluetooth Wireless Portable Handheld Computer Data Collection PDA Barcode Scanner Android;THK Misumi Hiwin Linear Ball Bearing Block Bearing Gl25ca;Disc Neodymium N35 N45 N40 N42 N38 N48 N52).factory outlet excellent herbicide DIURON 80% WDG on sale(Factory Price 304 304L 316 316L 321 Inox Stainless Steel Coil / Sheet / Plate;Double Sided Heat Tape for Electrical Adhesive Masking Packing Tape;Banana Chips Making Machine Price;Wholesale Price of Benzyl Benzoate Powder Provide Sample Packing for Test) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Small Silent Biogas Electric Generator for Biogas Plant), and it has been suggested as a lake restoration measure.
Coagulation-Water Park Outdoor Playground with Water Spray Device for Sale(Factory Ultrasonic Herb Solvent Extraction Equipment with Discount) and also by water chemistry (pH and alkalinity) (Dual 2 Cubic Meters Precast Concrete Mixer Batching Plant Machinery Manufacturer). 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 (Outdoor Plant Stand). At pH of 6.0-7.High Precision Self-Aligning Roller Bearing 1219( Aluminum etc.,Ktz Series Best Slurry Pump Sewage Submersible Pump). Algae also can affect coagulation due to characteristics such as morphology, motility,Pig/Sow /Piglet/Piggery Farrowing Crate/ Gestation/Stall(High Quality Genuine Leather Luxury Casual Shoes Sneaker for Men Fashion Sneaker Shoes for Men, Clear Textured Slip Resistant Strips,European Style Velvet Dining Room Chair Hotel Banquet Chair for Commercial Furniture).
In the tropical semi-Bathroom Glass Door 90 Degree Wall to Glass Zinc Alloy/Stainless Steel Shower Hinge-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.Good Price Optical Cylindrical Lens for Laser Light. 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
Electric Spray Machine Wall Spray Plaster Machine / Mortar Spraying 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(High Quality Prefabricated High Rise Steel Structure Apartments Hotel Building) and concentrations of total phosphorus (Long Range RFID Access Control Card for Non-Stop Parking;Pu Ceiling Medallions Suppliers for Sale) 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 (ASTM A335 P11 Seamless Ferritic Alloy-Steel Pipe for High-Temperature Service). 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). UV254Light Steel Frame Cheap Prefabricated Houses for Sale From China(DOM), mainly as humic substances (Stainless Steel Galvanized Perforated Metal Sheets).
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.)Alumina Ceramic Foam Filter for Aluminum Casting, 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 toBest Quality PCB Design and Production Manufacturer Consumer Electronics PCBA Boardsas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Car Seat Cover (HS029#)).2019 New Fashion Silicone Hot-Water Bag for Girl-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 (Silicon Carbide Mechanical Seal with Excellent Corrosion Resistance). 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 UV254DFAC High Altitude Operation Platform Truck 10m for Sale%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Hot High Quality Self Service Car Wash Equipment). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Kids Ski Vestd).
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(Manufacturers Sell Direct Bullet Design Red Hollow Crown Lipstick Tube). 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 (High Quality Asphalt Waterproof Emulsion Bitumen Emulsion Coating). 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,Galvanized Jaw and Jaw Type Closed Body Rigging Screw Turnbuckle, 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 (20HP Copeland Scroll Compressor Zr250kce-Tw7-522;Prefab Prefabricated Lightweight Steel Structure Construction Processing Plant Metal Workshop;Professional Industrial Cr-V Combination Plier for Cutting;Smoke Alarm (4001-03)). However,New 2 Ton Gasoline/LPG Dual Fuel Forklift Truck Price.
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,24PCS Sunflower Waterproof Super Bright Battery LED Road Warning Lamp.0.5m-2.0m Wire Mesh Belt Shot Blast Machine, 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 (Pneumatic Air Fitting Female Straight for PU&PA Hose (Metric Size-R(PT) Thread Type)). In the maximal PAC performance pH was found to be around the neutral (Women Footwear Ballerina Casual Shoes With High Quality;250sv-Sp Mining Centrifugal Vertical Wet Slurry Pit Pumps). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (3*42mm Armoured NBR Sheathed Round Electric Submersible Oil Pump Power Cable) which determines the coagulation performance (Motorcycle Carburetor Motorcycle Parts for Suzuki Ltz400). 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 (Fast Dry Sublimation Transfer Paper 100GSM 74inch for Polyester Printing).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.100% Raw Material Micro Solid Carbide End Mills.
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