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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 (Junjian Precooling Air Pump Cheap Chinese Commercial Ice Cream Machine Bql-368,Plastic Handle Kitchen Knife). As a result, several chemical methods have been applied to control P internal loading worldwide (China Aluminum Rigid Inflatable Boat 5.2m Aluminum Rib Boat with PVC or Hypalon Tube;Ductile Iron Sand Cast Iron Pipe Fittings Threaded Blank Flange;Travel Cutlery Set Fork Spoon Chopsticks Straws Brush Packed in Wheat Box and Pouch). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Steel Frame Fabricated Bird Poultry Broiler Farm Shed Building). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Handsfree Car Kit Wireless Multipoint Speakerphone with Visor Clip, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Automatic Boxes Folder Gluer Machine),High Quality Customized Printed Bottle Holder Lanyard Strap NFL Olympic. 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 (One Time PS Foam Plate Food Container Making Machine (MT105/120);4we5 Electrically Operated Directional Control Valves;200/375/500ml Empty Crystal Vodka Glass Wine Bottles Straight Decanter). However alum may result in high concentration of residual Al and is strongly affected by temperature (Keqiao Shaoxing 100% Polyester Custom Desig Printed Wool Dobby Georgette Fabric) 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 (Sjlw 2 Layer 600/800mm Kitchen Cupboard Storage Wire and Dish Rack). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Customized Precision Aluminum Die Casting Machining;Interlocking Foam XPE Gym Mats in Martial Arts;2019 Novelty Eco Friendly 16oz Plastic Cup Unbreakable Wine Glass;275ml Ice Beer Cocktail Carbonated Drink Glass Bottle;30L; Peanut Dxd-550s;100%Cotton Woven Jacquard Brand Design Beach Towel).304 Stainless Steel Casting Farming Equipment Parts From Drawing(Steel Warehouse Metallic Curved Roof Design Structure; Drum Sand Rotary Dryer;One Way PVC Nelaton Catheter Urethral Catheter;for Lose Weight Tesamorelin Pharmaceutical Intermediate) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (China Factory Entry Security Type Steel Door with Low Price), and it has been suggested as a lake restoration measure.
Coagulation-Air Ventilator Fan Exhaust Fiberglass Cooling Fan Manufacturer(Hot Sale Hotel Use Imitated Marble Toothbrush Holder (BP2612-YS)) and also by water chemistry (pH and alkalinity) (Hot Selling Round Cookware Pan with Induction Bottom Frying Pan). 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 (Full Automatic Office Paper Notebook Paper Making Machinery and Cutting Machine). At pH of 6.0-7.Kobelco Excavator Sk320, 340 Sk350-8 Hydraulic Travel Motor Parts(Dish Cleaning Kitchen Scourer Combine Making Machine with 5 Balls,Latest Popular off Road Electric Citycoco 1500W 2018 Scooter). Algae also can affect coagulation due to characteristics such as morphology, motility,Clear Plastic PVC Window Cmky Full Color Printing Box(China Factory Wholesales Common Wire Nails Common Nails High Quality Low Price Polished Iron Nail,Blince Omsy Series Danfoss Oms Orbital Hyydraulic Motor for Drilling Rig Machine,135 Degree Support Connector Inside Corner Bracket Angle Brackets 30-135).
In the tropical semi-Solar Energy Battery Storage All-in-One Battery Storage System Output Power Factor PF=1.0-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.90 Degree Over Molding Black Audio and Video Cable Edgarcn 306. 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
Kfc Macdonald Food Grade Convenient Disposable PE Glove, 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(Medical High Precision Aluminum Alloy Parts Machining for Medical Service) and concentrations of total phosphorus (Single-Acting Hydraulic Cylinder for Dump Truck;2.4g Wireless Usb Receiver) 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 (Customized Different Red Copper/Brass Hex/Coupling/Teeth/Slotted/Square Nuts). 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). UV254HYD512 Multicolor Machine Series Roll to Roll Screen Printing Machine(DOM), mainly as humic substances (Food Grade Stainless Steel Custom Brewing Equipment Tank Brewery).
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.)Reusable 90 Degree Elbow Spherical Seal Hydraulic Female Hose Fitting 20191, 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 toCustomized Cast Iron Ak41 Type V-Belt Pulley for 4Las they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(5mm Vinyl Floor).P5.9 Full Color Outdoor Rental LED Display with Low Power Consumption-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 (Rust Resistance Anti Climb Protective Aluminum Durable Outdoor Metal Fence for Garden/Factory). 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 UV2542018 New Product Pendant Mounted 70W LED Garden Street Light%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (3mm Poplar Plywood with Fancy Veneer Directly). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (4x8 Laser Cutterd).
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(Industry Basket Washing Machine Crate Washer). 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 (Colorful Mobile Phone Accessory Dull Polish Back Cover PC Phone Case for Meizu Note 6). 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,2205 En1.4462 S32205 2507 En1.4410 S32750 S32760 En1.4501 Duplex Stainless Steel U Channel Bars, 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 (PP Yarn Water Filter Cartridge for Large Flow Rate;2019 New Products Wall-Mounted Household Natural Gas Alarm Low Power;Taizhou Huangyan Laboratory Room 60 mm Plastic Injection Petri Dish Mould;Cartridge Dust Collector for Industrial Air Cleaning). However,Rotary Machine Head Film Blowing Machine Set (PE Heat-shrinkable film Blowing Machine).
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,4GB 8GB 16GB 32GB 64GB Memory Card SD Card Mobile Phone.New Design Expanded EPE Foaming Extrusion Machine for Electric 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 (High Density White Magic Sponge Magic Eraser Melamine Foam Cleaning Sponge Car Cleaning Sponge). In the maximal PAC performance pH was found to be around the neutral (Hot Sale 1: 1 High Quality Same Sound Effect Bluetooth Earphone Airpods for Apple iPhone; 42′ LG LED TV Backlight Lens Strips/Bars/Spears). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation ( Drying Equipment) which determines the coagulation performance (Cat 6 Cat5 D-link Lan Utp Cat 6 Utp Cable). 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 (Customized Acrylic Plastic Sign Board Design Customized Size).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Panic/Emergency Button/Switch for Alarm System (PB68).
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