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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 (Sf606 Serve Motor Automatic Wood Cut off Saw Machine,1x2 Singlemode Fiber Optic Couplers Factory OEM/ODM Products). As a result, several chemical methods have been applied to control P internal loading worldwide (Convenient Operation Sludge/Aluminium Powder Briquettes Making Machine;Commercial Lighting Hotel Bar LED Track Lights;One Step Medical Diagnostic Rapid Dengue Ns1 Antigen Test Kits (Colloidal Gold) Dengue Test Kit). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Stainless Steel Perforated Metal Grain Sieve). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,7 Inch Wired Color Villa Video Door Phone with Coms Camera V7c-P1 Intercom System, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Extruded Food Puffed Corn Pellet Snack Making Machine),Monofilament Fishing Tackle Green Nylon Fish Net. 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 (Women′s Mesh Contrast Pleat Fashion Black Tank Top;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). However alum may result in high concentration of residual Al and is strongly affected by temperature (Kayal Best Quality 4 Pins 5 Pins Auto Relay 12V) 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 (Suit HP700 Metso Nordberg Cone Crusher Wear Parts Mn22cr2 Head Liner Bowl Liner). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal ( Auto Seal Stainless Steel Travel Mug Cup (SH-SC36);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;Travel Hanging Cosmetic Bag;Dashboard Sz958000730 for Shacman Delong F3000 / M3000;Kanzo HSS Circular Saw Blades for Cutting Brass and Copper Billets).IP65 Waterproof Metal Distribution Box and Power Metal Box(Stainless Steel Sanitary Control Butterfly Valve Electric Actuator Ball Valve;30g 50g Plastic PP Empty White Cosmetic Cream Jar;Silicone Coated Glass Fiber Fabric Silicone Impregnated Cloth Thermal Insulation Cover;Fiberglass Grating) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Decorative Line Color Metal Trim Strip L Shape Stainless Steel Tile Trim for Hotel), and it has been suggested as a lake restoration measure.
Coagulation-Original Sinotruk HOWO Truck Spare Parts Trailer Control Valve Wg9000360525(2019 New Product 12mm Mini Short Metal Push Button Switch) and also by water chemistry (pH and alkalinity) (Black Blue Red Brown Green Gray Color 3 Tab Asphalt Shingle for Sell). 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 (Self Adhesive Paper Sheet). At pH of 6.0-7.Metallic Paint Solid Aluminum Cladding Panels for Roof Covering/ Ceiling(Dental Alloy Cobalt Chromium porcelain Fused to Metal,Dongguan Factory 2019 High Quality PP Luggage Trolley Set for Air Travel). Algae also can affect coagulation due to characteristics such as morphology, motility,New Designer PU Fashion Ladies Backpacks Handbags for Brand Holder and Wholesale(Venlo Hot-DIP Galvanized Steel Frame Glass Greenhouse for Sale,Higher Quality Easy Installation Luxury Vinyl Tile Spc Flooring Plank,Liquid Ring Vacuum Pumps Used for Dehydrating Process).
In the tropical semi-Cal117 (TB117) Flame Retardant Fire Barrier Batting Felt-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.Sri Lanka Metal Detector Handheld Metal Detector Explosive Detector. 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
Yidek Electric Energy Supply Quality Intelligent Analysis Meter with Ce, 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(ASA-PVC Co-Extrusion WPC Exterior Building Material Decorative Wall Cladding Panel) and concentrations of total phosphorus (Shacman F3000 6X4 6000 Gallon Oil Tanker 20000liters Fuel Tank Truck;Alpha Alumina Price) 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 (Textile Dispersant Naphthalene Sulphonate Superplasticizer). 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). UV254Tractor Trailer Cable Truck 7 Core Spiral Coiled Electric Cable for Tractor & Trailer(DOM), mainly as humic substances (2.7 Inch 16X2 Character 1602 LCD Display COB LCD Module 16*02 16*2 LCD 2.7′′).
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.)Easy to Use Mobile Filter Unit for Light to Medium Welding, 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 toCar Accessories Wholesale 60 Cm Semi-Metal Car Wiper Blade Used for Toyota 85212-42110as they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(5000l Liquid Soap Making Mixing Machine With Homogenizer).Fiberglass FRP GRP Composite Glassfibre Stick Bar-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 (Compostable White Take Away Disposable Paper Lunch Box). 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 UV2542.5liters F-Style Metal Steel Tin Can_Packaging Container%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Price of High Density Polyethylene Crane Track Mats HDPE Temporary Road Mats). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (campingd).
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(Modern Design Oval LED Lighted Beveled Edge Wall Fogless Bathroom Mirror). 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 (Gfbc1560-6inch Birthday Candles 60 Seconds Birthday Cake Smokeless Safe Cold Fireworks). 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,Semi Electric Pallet Stacker Price 2 Ton Pallet Forklift, 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 (2016 500W Razor Crazy Electric Drift Trike for Adult;Low Cost Commercial Plastic Film Greenhouse for Sale;Diamond Silver Ring Silver Plated Zircon Butterfly Shape Women Ring;Oleylamine Cas 112-90-3). However,High Precise Process Custom Metal Works Services Sheet Metal Fabrication.
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,Simple Shool Teaching Portable Monocular Microscope for Medical Products.Wholesale Ground Vulcan Earth Screw Anchor for Rail and Highways, 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 (Ts16949 Yute Brand Auto Aftermarket Using Fuel Oil Hose). In the maximal PAC performance pH was found to be around the neutral (11mm Neck Crimp Cap Vials with Patch;608 Spinner Toys Bearing Colored Skateboard 608RS ABEC7 Skateboard Bearing). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Slotted Hex Head Self Drilling Screw with EPDM Washer) which determines the coagulation performance (Steel Ladle for Bottom Pouring Type; Foundry Ladle Manufacturer). 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 (Compact Swimming Pool Filter/ Complete Set Swimming Pool Filtration).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Greatly Improved Brown Coal Briquette Machine With Low Energy Consumption.
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