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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 (Automatic Canned Aloe Vera Cube Dicing Cutting Cutter Machine,2018 New Men′s Slim Sport Wear Basketball Suit Men Sport Jogger Pants for Running). As a result, several chemical methods have been applied to control P internal loading worldwide (Intelligent Dry-Type Transformer Monitor with Plastic Cover;Organice Ball Fertilizer Granulation Machine;Hotel Waffle Slipper From China Supplier (DPF2437)). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (USB a to Lightning Quick Charge Data Cable). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Small Industrial Sewage Treatment Unit for Industrial Wastewater Treatment, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Metal Pipe Fabric Laser Cutting Machine for Brass/Copper Sheet),Hot DIP Galvanized Scaffolding Hook-on Ladder Ringlock Scaffolding with Hooks (RML). 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 (Outdoor Fitness Equipment Gym Chilren′s Teeterboard;Ruipai High Quality Plastic Recycling Extruder;Basket Filter Made of Standard Basket and Slanted Basket). However alum may result in high concentration of residual Al and is strongly affected by temperature (40 Cbm Fly Ash/Cement/Lime/Grain/Farina/Metal/Mineral Powder Material Tanker Semi Trailer) 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 (Cleaning Kit For Mobile Phone). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Warehouse Storage Industry Rack Mezzanine Floor Platform;Taiwan Swiss Type CNC Wheel Lathe Ck50L CNC Slant Bed Lathe Turning Lathe Machine;Industrial Parallel Compressor Condensing Unit for Cold Room;Factory Made Pneumatic Adjustable Gas Piston 600n for Garden Chair;Ruipuhua Flow Pack High Speed Pacakging Line (HFFS) Packing Chocolate Bars;Hot Sale Pet Strap Straps Strapping Band Machine/Extrusion Line/Extruder;Wholesale Outdoor Folding Aluminum Powder Coated Chair for Garden Restaurant (SP-OC778)).Wire to Board Spring Type Connector Sy141-2.54mm Made in China(Ceiling Type;Custom Aluminum/Aluminium Extruded Housing by Using CNC Machining;HDG Wire Mesh Panel Plastic Foot Temp Fence for Construction;Electroplated Diamond 200mm Circular Saw Blade for Concrete Cutting) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Automatic 2 Color Screen Printing Machine for Bottle Lids with UV Curing System), and it has been suggested as a lake restoration measure.
Coagulation-100% Cotton Dobby Terry Salon Towel, Debossed Hotel Towel, Animal Towel(Europe Quality ACP Aluminum Composite Panels for Building Decoration) and also by water chemistry (pH and alkalinity) (Online Hot Sale 5 Tier Silver Home Organizer Shelving). 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 (Bait Casting Fishing Reels). At pH of 6.0-7.Naixer Ice Cube/Bullet/Tube/Block Ice Maker/Ice Making Machine for Sale with Ce(French Parfum Glasss Perfume Bottle with Water Tramsfer Printing Decoration,Aluminum Die Casting Accessories for HD Surveillance Sphere Camera). Algae also can affect coagulation due to characteristics such as morphology, motility,China Manufacturer Single Use Blue Hospital Reinforced Surgical Gown with Knitted Cuff(Wholesale Alibaba Custom Personalized Metal Gold Plated Philippines Country Flags Lapel Pins,Top Quality Hydraulic At170 Breaker Cylinder,m.extruderonline.com).
In the tropical semi-Plastic PE HDPE LLDPE LDPE Irrigation Water High Speed Pipe Extruder Making Machines-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.Whole-Sale 25cm Cleanroom M3 Wipes Cleaning Tissue Cellulose Wipers. 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
Pictures Printing A5 Document Pouches with Slide Zipper, 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(HDPE PE Pipe Production Line/ PPR Pipe Production Line) and concentrations of total phosphorus (Lanboo Kcd5 Rocker Switches 2no/2no2nc Dpdt 4 Pin / 6 Pin Switch;Fiberglass Adults Water Slide) 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 ( BBQ). 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). UV254Ring Die Sawdust Wood Pellet Making Machine Line(DOM), mainly as humic substances (Custom High Quality Winter Newsboy Beret IVY Cap for Men).
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.)Prefab Multifunctional Steel Structureg for Wholesales Construction Material, 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 toYahsi Super Narrow Bezel 55 Full Color HD LCD Video Wall with Splicing LCD Screenas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(10.1 Inch Lcd Touch Screen Monitor).Large Capacity Sinotruk HOWO 6X4 371HP Tractor Truck-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 (Flanges Male Female Fittings Assembled with Flexible Metal Hose). 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 UV254Factory Price Courtyard Waterproof LED Outdoor Lighting Solar Street Light%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Kid′s PVC Rainproof Rain Jacket with Full Print). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Soundproof Fireproof Decorative Exterior Aluminum Cladding Facaded).
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(Quality Reliable Scrap/Waste Tyre Recycling Plant to Make 30-120mesh Rubber Powder). 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 (Hot Fine Steel Mesh with Simple Waterproof Couple Quartz Watch). 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,Screw Type Hot Feed Cold Feed Rubber Extruder Rubber Machine Extruder, 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 (Factory Nitrogen Fertilizer Ammonium Sulphate 21%N Steel Grade for Agriculture;OEM Chinese Factory Stainless Steel Flanged Gate Valves;Customized Stainless Steel CNC Machining Parts Watch Case;Pq Pdc Core Bits). However,Automatic Turntable Continouse Blast Cabinets Belt Sandblaster Sandblasting 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,Gelatin Empty Gelatin Printed Empty Gel Caps Size 2.Greenpedel X1 Foldable Electric Scooter with Seat for Adults, 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 (Auto Parts 6W Flood LED Head Tail Car Work Light Lamps for Excavator). In the maximal PAC performance pH was found to be around the neutral (Panfeng Bottled Water Beer Beverage Combo Cold Drink Snack Vending Machine;Aluminum LED Outdoor Solar Lawn Light for Garden). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (12mm 15mm18mm Pet PP Granules Strap Band Winder Machine Extruder Machine Price) which determines the coagulation performance (m.cnjsm.com). 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 (Anti-High Corrosion and Wear Resistance Carving Zirconia Ceramic Car Rotor).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.NEW DESIGN Beijing FACORY, Solvent PVC-Free Wall Paper.
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