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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 (250ml Medical Transparent Ultrasound Ultrasonic ECG Gel Wholesale Price,316L Seamless Stainless Steel Tube by ASTM A269 Standard). As a result, several chemical methods have been applied to control P internal loading worldwide (Top Supplier Lcoe Cost Down 1500V Dual Glass 320W 330W 340W Poly Solar Panel;Hybrid Power System 150kw Electricity Generating System with Battery Bank;Customzied SKD11 Shear Blades for Leather and Plastic). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) ( Keyboards). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,High Pressure Zirconia Ceramic Piston Rod Pump Ceramic, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Scissors Lift),Brown Shoes High Quality Strong Protection Working Shoes. 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 (10kv Xple Heat Ahrinkable 1-Core Outdoor Termination Kit (Section 500~630 mm^2);Aluminum/SS304 Material Bathroom Mirror and Satin Shower Glass Sliding Door Handle;Sermorelin Powder Anabolic Raw Powder for Human Grow Hormone). However alum may result in high concentration of residual Al and is strongly affected by temperature (Beautiful Lvt Eco-Indoor Wood Grain Click Planks Vinyl WPC Flooring) 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 (Radial Film Capacitor). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Ae Bifacial Solar PV Panel 270W Poly German Quality;Long Rod Electrical Suspension High Voltage Polymer Insulator;Chemical Vacuum Coating Single Stage Rotary Piston Pumps;Original Germany Bitzer Brand Compressor 4hc-1.2y;Floor Stand Lcd Advertising Display;Custom Black-White Printed Product Operation Instruction;Spdt Floating Valve Motorized Zone Valve for Water Pressure Regulator).700ml Leak Proof Fitness Plastic Protein Mixing Water Cup (HDP-0346)(High Precision Die Cutting Machine Packaging Flatbed Cutter Vct-MFC6090;Flexible PVC Steel Wire Reinfoced Spring Hose;Rotor Permanent Magnet;55 65 75 86 98 Inch 3D LCD Touch Screen Smart Board TV All in One PC for Meeting Room & Classroom) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Soft Touch 22 Inch Reborn Silicone Baby Doll Kits), and it has been suggested as a lake restoration measure.
Coagulation-4we5 Electrically Operated Directional Control Valves(New Design Silicon Watch Band Strap for Apple Watch Series 4 Mesh Shape Sport Band for Apple Watch) and also by water chemistry (pH and alkalinity) (PU Imitation Clothing Leather Garments Material -Freman). 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 Popular Factory LED Tube T8 1200mm Tube Light). At pH of 6.0-7.Single Head High Speed Tubular Cap Embroidery Machine (TLC901)(Toner Cartridge Chip for Ricoh Aficio MP C3002 3502 (841735~841738 841647~841650),Facial Cleaning Cellulose Sponge for Cosmetics Makeup Brush Clean). Algae also can affect coagulation due to characteristics such as morphology, motility,Communication Cable Rg59/RG6/Rg11 Coaxial Cable Copper Standard Wire Satellite System(7 Inch Ultrasonic Digital Video Reverse Parking Sensors for Truck,Slip on Blind Weld Neck Stainless Steel Flange Including Welding Neck Flange,5kg 10kg 15kg Dog Pet Food Packaging Plastic Bag).
In the tropical semi-High Speed LDPE Polyethylene Plastic Film Extrusion 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.Telescopic Aluminum Square Tent Pipe&Drape for Wedding/Event. 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
Oven and BBQ Digital Cooking Thermometer with Stainless Steel Probe, 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(Sf606 Serve Motor Automatic Wood Cut off Saw Machine) and concentrations of total phosphorus (Convenient Operation Sludge/Aluminium Powder Briquettes Making Machine;Black Carbon Steel Pipes From China) 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 (Stainless Steel Perforated Metal Grain Sieve). 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). UV254Caprolactam Grade Ammonium Sulphate (21%Min)(DOM), mainly as humic substances (Women′s Mesh Contrast Pleat Fashion Black Tank Top).
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.)Micropile Tube as Umbrella for Tunnel Portal Od139.7mm Wt9mm, 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 to Auto Seal Stainless Steel Travel Mug Cup (SH-SC36)as they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Automatic Ultrasonic Strap Cutting Machine Products Made in China).NdFeB Magnetic Strong Sintered N45 Rare Earth Permanent Neodymium Magnets for Motor-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 (Customized Lift Gas Support Spring with Metal Eyelet End Fitting). 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 UV254Hexagon Commercial Nylon Carpet Tiles/Office Carpet Tiles/Sexangel Carpet Tiles%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Dashboard Sz958000730 for Shacman Delong F3000 / M3000). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Prefab Housed).
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(Stainless Steel Sanitary Control Butterfly Valve Electric Actuator Ball Valve). 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 (30g 50g Plastic PP Empty White Cosmetic Cream Jar). 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,19 Inch IP65 Waterproof Design Industrial Tablet Computer for Industrial Automation Equipment, 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 (2019 New Product 12mm Mini Short Metal Push Button Switch;Black Blue Red Brown Green Gray Color 3 Tab Asphalt Shingle for Sell;Dental Alloy Cobalt Chromium porcelain Fused to Metal;Factory Provide Directly Stainless Steel Folding Platform Industrial Platform Scale). However,Two Walls Stainless Steel Insulated Straw Cup Step Shape Metal Juice Cup with Straw.
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,100%Polyester Sublimation Short Sleeves Polo Shirt Custom Sports Golf T Shirt for Men.Concrete Road Cutting Machine, Road Cutter, Road Saw 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 (Dongguan Factory 2019 High Quality PP Luggage Trolley Set for Air Travel). In the maximal PAC performance pH was found to be around the neutral (Venlo Hot-DIP Galvanized Steel Frame Glass Greenhouse for Sale;Higher Quality Easy Installation Luxury Vinyl Tile Spc Flooring Plank). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Roll Forged Steel Sheaves for Crane Sheave Block) which determines the coagulation performance (Glassware Washer Laboratory). 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 (Wholesale Red Half Frame Interchangeable Lenses UV400 Outdoor Sport Cycling Running Sunglasses).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Diesel Engine Parts Cylinder Head for Mitsubishi 4D30A/4D31 Me999863.
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