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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 (Convenient Operation Sludge/Aluminium Powder Briquettes Making Machine,Quartz Lens). As a result, several chemical methods have been applied to control P internal loading worldwide (Commercial Lighting Hotel Bar LED Track Lights;One Step Medical Diagnostic Rapid Dengue Ns1 Antigen Test Kits (Colloidal Gold) Dengue Test Kit;Stainless Steel Perforated Metal Grain Sieve). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Women′s Mesh Contrast Pleat Fashion Black Tank Top). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,CNC Turning Stainless Steel Part with Precision Tolerance, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Zy-26 Portable Bag Closer Zoyer Sewing Packing Sealing Machine),Depilation Aesthetic Opt Shr IPL Elight RF Hair Removal 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 (130 T/H Water-Cooling Vibrating Grate Cotton Fired Boiler for Power Plant;24-410 White PP Plastic Land Seal Pivot Spout Caps for HDPE Cylinder Bottles;Kayal Best Quality 4 Pins 5 Pins Auto Relay 12V). However alum may result in high concentration of residual Al and is strongly affected by temperature ( Auto Seal Stainless Steel Travel Mug Cup (SH-SC36)) 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.goldenvision-lcd.com). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Port Bulk Cargo Tire Mounted Truck Loading Dust Control Eco-Hopper;VRLA Deep Cycle Storage Battery 12V 100ah (QW-BV100A);Customized Lift Gas Support Spring with Metal Eyelet End Fitting;Dashboard Sz958000730 for Shacman Delong F3000 / M3000;Steel Grate Grill;Kanzo HSS Circular Saw Blades for Cutting Brass and Copper Billets;Stainless Steel Sanitary Control Butterfly Valve Electric Actuator Ball Valve).Fashion Double Striped Non-Slip Entrance Mat(30g 50g Plastic PP Empty White Cosmetic Cream Jar;Fiberglass Grating;Diesel Engine Hammer Mill;Decorative Line Color Metal Trim Strip L Shape Stainless Steel Tile Trim for Hotel) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (2019 New Product 12mm Mini Short Metal Push Button Switch), and it has been suggested as a lake restoration measure.
Coagulation-145g 5X5mm EPS Fiberglass Reinforced Wire Mesh Price for Plastering in Europe(Black Blue Red Brown Green Gray Color 3 Tab Asphalt Shingle for Sell) and also by water chemistry (pH and alkalinity) (Dental Alloy Cobalt Chromium porcelain Fused to Metal). 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 (Sports Rubber Silicone Wristbands). At pH of 6.0-7.Stainless Steel Perforated Metal Grain Sieve(Dongguan Factory 2019 High Quality PP Luggage Trolley Set for Air Travel,Venlo Hot-DIP Galvanized Steel Frame Glass Greenhouse for Sale). Algae also can affect coagulation due to characteristics such as morphology, motility,Stainless Steel Grating for Chemical Plant Platform(Higher Quality Easy Installation Luxury Vinyl Tile Spc Flooring Plank,Roll Forged Steel Sheaves for Crane Sheave Block,Professional IP66 800watt Outdoor Basketball/Football/Soccer Field LED Flood Lighting).
In the tropical semi-Pet Strap Production Line with Good Quality-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.Commercial Lighting Hotel Bar LED Track Lights. 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
High Pressure Rubber Hydraulic Hose Assembly, 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(Shacman F3000 6X4 6000 Gallon Oil Tanker 20000liters Fuel Tank Truck) and concentrations of total phosphorus (Ce Approved Cheap Medical Disposable Electrical Infusion Pump;4G Module) 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 (2.7 Inch 16X2 Character 1602 LCD Display COB LCD Module 16*02 16*2 LCD 2.7′′). 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). UV254Dn300 12 Plastic Butterfly Valve with Explosion-Proof Electric Actuator(DOM), mainly as humic substances (Morgan Carbon Brush/Carbon Brush for Forklift/Denso Window Motor Brush).
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.)High Quality Adjustable Ball Valve Lockout for 13-70mm Pipe Bd-F05, 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 toFashion Classic Korea Designs Denim Pinafore Teen Dress for Kidas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Metal Sheet Stamping).Wholesale LCD Replacement Touch Digitizer Full Original Assembly Display for Apple iPhone 6-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 (Price of High Density Polyethylene Crane Track Mats HDPE Temporary Road Mats). 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 UV254Travel Luggage Scale with Tape Measure Function%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Factory Direct Seal Y14f General Power Relay 5 Pins). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Hot Selling Outdoor LED Screen Prices LED Advertising Displayd).
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(Gfbc1560-6inch Birthday Candles 60 Seconds Birthday Cake Smokeless Safe Cold Fireworks). 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 (Flexible Cloth Backdrop P18 3X6m LED Video Curtain). 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,Aluminum Square Bar, Aluminum Round Bar, Cutting Bar, 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 (Low Cost Commercial Plastic Film Greenhouse for Sale;Diamond Silver Ring Silver Plated Zircon Butterfly Shape Women Ring;Ts16949 Yute Brand Auto Aftermarket Using Fuel Oil Hose;AC Electrical Gear Synchronous Motor for Quarz Hearter Grill Reluctance). However,Fashion Sports Woven Wristband with Print Logo.
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,Facial Cleaning Cellulose Sponge for Cosmetics Makeup Brush Clean.Aluminium Fabric Garden Coffee Shop Outdoor Dinning Chair, 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 (11mm Neck Crimp Cap Vials with Patch). In the maximal PAC performance pH was found to be around the neutral (608 Spinner Toys Bearing Colored Skateboard 608RS ABEC7 Skateboard Bearing;Slotted Hex Head Self Drilling Screw with EPDM Washer). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Compact Swimming Pool Filter/ Complete Set Swimming Pool Filtration) which determines the coagulation performance (21.5 Inch aerial display). 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 (Inlet Pipe for 93-02 Toyota Supra 2jz Ge Down Pipe Downpipe).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.SUS304 or 316L Stainless Steel Vacuum Kettle Steam Cooker.
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