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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 ( IPS 720*1520 Display Android 9.0,Portable Laser Cutting Machine). As a result, several chemical methods have been applied to control P internal loading worldwide (Auto Car Parts Good Quality 16620-0s010 Tensioner Pulley;Women′s Stretchy Yoga Training Mesh Leggings with Side Pocket;Wholesale Promotional Children Painting Apron). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Poultry Farming Automatic Chicken Feeding Pan System). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,High Manganese Casting Nordberg Gp100 Mantle Cone Crusher Parts, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (2019 3D Stone Wooden Brick Design PVC Interior Wallpaper),Manufacturer New Design Reusable Clear Lalique Glass Perfume Packaging Bottle. 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 (600W Mini Lathe Metalworking 7 X 14 Tool Turning Machine;Custom High Quality Clear BOPP Adhesive Tape for Carton Sealing;Automatic Concrete Paving Interlocking Block Brick Making Machine). However alum may result in high concentration of residual Al and is strongly affected by temperature (OEM Custom Cotton Twill Flat Top Military Army Hat and Cap) 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 (Laptop Handbag). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Wood Grain Vinyl Films/Self Adhesive Decorative Paper for Furniture;Attractive Kids Trampoline Park for Jump Baby Indoor Soft Play Equipment Theme Parks for Sale;Fish Scale Shaped Waterproof Roof Tile for Roof Tile;Hydraulic Control Valve-100A Angular Stable Water Level Valve;500 PC Car Body Aluminum Fasteners Trim Moulding Clip Rivet;Direct Thermal Label with Premium Quality Adhesive Sticker Label;Wholesale Room Ozone Generator for Fruits and Vegetables).Xinjing Wide-Mouth Kitchen Glass Square Jar for Spice, Seasoning(Folding Dinner Table Set in Dining Room Furniture;Agricultural Low Cost Greenhouse Farming Equipment;Exfoliating Machine Face;Anti-Slip Crazy christmas Cute Funky Cotton Custom Socks) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Patterned Shoulder Nozzle Aluminum Tube for Glue/Medical Ointment Packaging), and it has been suggested as a lake restoration measure.
Coagulation-Dn100 4 Inch Rubber Seal 220VAC Wafer Type Electric Actuator Butterfly Valve(Light Steel Frame Cheap Prefabricated Houses for Sale From China) and also by water chemistry (pH and alkalinity) (Eco-Friendly Material Restaurant Furniture Metal Stainless Steel Desk Leg Table Base Legs (TB-04)). 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 (Wholesale Cheap Custom Epoxy 3D Fridge Magnet for Sale). At pH of 6.0-7.HDPE PE Pipe Production Line/ PPR Pipe Production Line(Fsi 5kw 24VDC Pure Sine Wave Hybrid PV Solar Inverter with High Efficiency MPPT Controller,Mobile Phone Jammer + WiFi / GPS / 4G Jammer 6 Bands). Algae also can affect coagulation due to characteristics such as morphology, motility,Shenzhen Customized Metal Stamping Parts Fabrication Service(Professional Korea Hifu Focused Ultrasonic Beauty Machine for Wrinkle Removal,Durable Life Stainless Steel Knotted Cable Mesh,Discount Inflatable Floating Water Playground/Water Amusement Park).
In the tropical semi-High Tensile Wire Rope Lifting Jaw Jaw Turnbuckle Rigging-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.Desktop Digital Servo Control Universal Material Tensile Testing Machine 8201s. 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
UV Digital Flatbed Printing Machine Seiko-1024, 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(Light Weight FRP XPS Composite Panel for Mobile Home Construction) and concentrations of total phosphorus (OEM Metal Iron/Carbon/Steel Hammer Forging for Cylinder/Raiway Wheels;8-32mm Plastic Rebar Cap) 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 (Gdg24 0.55kw 550W 0.75HP 24L Oil Free Air Compressor). 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). UV25410-30V LED Combination Lamp Stop, Tail, Indicator, Reverse Trailer Lamp Truck Light(DOM), mainly as humic substances (Seu 2*8 AWG Concentric Service Entrance Cable).
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.)Topkit Tower Crane Rct6011-6 for Construction Building, 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 toChina Manufacturer Cement Plaster Storage Pressure Tank Containeras they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Finger Gasket For Shielding Door).200m Deep Top Driving Tractor Mounted Water Well Drill Equipment-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 (Activated Carbon Pellet Manufacturer Used for Gas Treatment). 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 UV254Hard Cover Planner Notes, Paper Diary Notebook, Drawing Book for Students%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Custom High Quality CNC Milling Acrylic Block Stainless Steel Aluminum CNC Precision Milling Service). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (New Design Kids Table And Chair Setd).
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(Fashion Italian Style Hotel Furniture Wooden Marble Dressing Table). 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 (New Product High Quality Home Smart Wireless Video Doorbell Camera). 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,2-Channel/4-Channel DC Current Voltage to RS232/RS485 a/D Converter, 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 (12oz Dispossable Ripple Wall Paper Cup with Good Insulation;Naked Mango Premium E-Liquid for Electric Cigarette;M3n 3.6-12V 27.8*32.5mm 12.34W DC Motor for Grass Cutter;Heat Reflective Heatsheild Material Golden Thermo-Shield). However,Commercial Beer Brewery Equipment Beer Fermenter Tanks (ACE-FJG-070249).
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,Best Selling Mirror Aluminum Sheet for LED Lights and Decorations etc..Tz03D High Quality China 20-40HP Garden Tractor Front End Loader Hot Sale in New Zealand, 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 (Double Breasted Wool Casual Long Kid Girl Coat Winter Fashion Jacket for ODM OEM). In the maximal PAC performance pH was found to be around the neutral (Luxury Fashion Lady Women Shoulder Tote Bag Leather Evening Handbag;Exhibition Fiberglass Portable Small Size Beach Flag/Flying Flag). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Qtj4-40 Mobile Block Making Machine Price List/Cement Block Maker Machine/Small Manual Block) which determines the coagulation performance (Wbacc Truck Desiccant Cartridge Same as Wabco 4324102227 Iveco 1900812 Air Dryer Filter (WBACC-01A)). 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 (Kynko Li-ion Cordless Drill with 18V Battery (KD30)).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.New Addition and Cheap Frame Upward 4 Column Hydraulic Press.
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