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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 (Finisher Kids Antique Sundown Marathon Sport Medal (071),Insert Ball Bearing with Plastic Pillow Blocks for Chemical/Food Industries). As a result, several chemical methods have been applied to control P internal loading worldwide (Eboat Healthy Cbd Oil Dosposable 0.5ml Window Design Vape;Stainless Steel 316L Pipe Schedule 40 Manufacture;New Model Cheap Unique Fashion Jewelry 925 Sterling Silver CZ Stud Earrings for Girls). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Promotional Gift Fabric Textile Polyester Elastic Round Bracelets for Event). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,LED Dancing Wing Props Halloween Christmas Party Supplies, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Best Price Blanket In China),AAC Autoclaved Aerated Concrete Brick Making Machine, AAC Plant Solution. 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 (Good Quality Delicious Instant Fresh Pasta Noodle;Hyaluronic Acid /Sodium Hyaluronate for Cosmetic Food Grade;1212 1218 1224 1313 CNC Router 4 Axis/Automatic 3D Wood Carver Machine with DSP Controller). However alum may result in high concentration of residual Al and is strongly affected by temperature (Folding Pile Driver Machine with Hydraulic Power) 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 (Animal Feed Hammer Mill). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Cast Iron and Forged Stainless Steel Basket & Y Strainer with Ss316 or Ss304 Screen;Wholesale RFID Paper Card Intelligent Smart Ticket for Subway or Park;Snooker China Top 1 26~909kg/24h Commercial Cube Ice Machine;Tisco High Quality Cold/Hot Rolled Stainless Welded Steel Pipe Grade 201;Brand New FAW heavy trucks/ Towing Tractor/ Ethiopia truck;Plastic PP/PS/Pet Mineral/Starbucks/Jelly Cup Thermoforming Making Machine;Yuanchen Nonwoven Needle Punched PPS Filter Felt).15.6 Inch LED Backlight Wide Screen HD LED TV Ce CB(Waterproof Spunbonded Flame Retardant Fabric for Function Textile;Made in China 6.5kw Heavy Duty Durable Gasoline for Honda Generator Gp7000;Electric Drive New Condition Carton Box Slitter Scorer Machine;Industrial Air-Cooled Low Temperature Water Chiller with Easy to Operate) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Spark Plug Wire/Ignition Leads Set/Ignition Coil for KIA Pride Zimens), and it has been suggested as a lake restoration measure.
Coagulation-Auto Crane Electrical Overhead Cable with Steel Wire(10kw 20kw 30kw 50kw Small Gas Generator for Home Use) and also by water chemistry (pH and alkalinity) (Fastener Screw /Self Tapping Screw / Machine Screw). 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 (GIRL POLOS). At pH of 6.0-7.Safety Bike for Cool Design Children Bike/Bicycle(Custom Angled Shape Slipper 100% Cotton Embroidery Logo Hotel Grey Disposable Slipper,Plastic Cable Electric Plug Making Machines Supplier). Algae also can affect coagulation due to characteristics such as morphology, motility,CCTV Security System Projects IP Camera Factory Hikvision IP Camera(Good Price PVC Ceiling Panel / PVC Ceiling Sheet and PVC Wall Panel,Factory Supply Robot Automatic Vacuum Swimming Pool Cleaner,Stainless Steel Cleaning Agent).
In the tropical semi-Eco-Friendly Euro Plastic Container with Lid-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.2.7 Inch 16X2 Character 1602 LCD Display COB LCD Module 16*02 16*2 LCD 2.7′′. 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
Professional Stage Lighting 7PCS 4in1 LED Flat PAR Lights, 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(20PCS Porcelain Dinnerware with Popular New Design) and concentrations of total phosphorus (Electric Control Polystyrene Cuttrt EPS Block Cutting Machine;Chicken Coop Cover) 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 (Spectrum Analyzer for Ferrous and Non-Ferrous Metals). 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/Brass/Copper/Carbon Steel Woven Wire Mesh with ISO Approved for Filtration(DOM), mainly as humic substances (Dust Proof Window Screen Mesh Aluminum Wire Mesh).
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.)Standard Air Small Sandblaster for Construction Machinery Cleaning, 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 toHigh Precision 3D Printer Kitas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Custom Design 6.3′′ Silicone Grenade Dabbing Nectar Collector Set with Titanium).Common Mode Choke, Transformer Used for Power Supply, EMC, Torodial Coil, UL, Ce, VDE,-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 (Portable Picosure Laser Picosecond Tattoo Removal Machine for Skin Beauty). 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 UV254Customized Dust Filter Cartridge Price for Industrial Welding Fume%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Stable Steel Flat Glass Transport Rack with Safe Support Protection). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (2019 New-Tech Thin Wet-Punching Tail-End Card Metallic Card Clothing Wired).
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(Ride on Concrete Power Trowel Machine with Suitable Seat). 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 (Vci Packaging Paper for Metal/Iron/Steel Parts Rustproof). 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,Chinese New Crop Watermelon Seeds Big Size Water Melon Seeds, 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 (10.5 Inch Silicone Straws and Stainless Steel Straws;Manufacturers 1000W AC/DC Converter Car Power Inverters;Stainless Steel 304 316 Railing Fittings Casting Round Tube Plate;25w Led Track Light High Quality Supplier). However,Standard Sizes Aluminium Galvanized Mild Steel U Channel.
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,Linyi Jianzhong Square Veneer Tube Dryer Wood Veneer Dryer Machine for Plywood.Rubber Raw Material Kneader Machine -75L Banbury Mixer, 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 (CNC High Speed Gear Hobbing Machine Ys3118CNC5). In the maximal PAC performance pH was found to be around the neutral (Indurstry Building Safety Boots with Steel Toe Cap and Midsole (SN1629);0.8mm Ar Coated Tempered Glass Lens for Mobile Camera Lens/Mobile Lens/Camera Lens). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (High-Precision Aluminium Casting Aluminum Die Casting Parts) which determines the coagulation performance (E Car Charger). 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 Quality and Low Price Aluminum Alloy Perforated Electrical Cable Tray).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Naixer Ice Cube/Bullet/Tube/Block Ice Maker/Ice Making Machine for Sale with Ce.
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