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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 (Fiberglass Mesh/Fiberglass Mesh Cloth/Fiberglass Netting Mesh,Hot Selling Pvc Pipe). As a result, several chemical methods have been applied to control P internal loading worldwide (No Pollution Ce RoHS 30W Indoor UV Insect Killer Lamp Fly Mosquito Glue Trap Catcher;Copper Standard Multi 2/4/6/8 Cores Alarm Cable Security Monitor System;Textile Mill Food Industry Garment Factory Oil Gas Steam Boiler). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (V4 Type Sintered Porous Filter with Female Thread). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Guard Rail Roll Forming Machine 2.0-4.0mm Thickness, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Essential Oil Glass Bottle),Flexible Semiauto Cosmetics Bottles Adhersive Labels Sticker. 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 (PVC Stripe Anti-Slip Door Mat with Color Logo;1200*2200mm Black Powder Coated Dutch Barn Stall Door;Hot Sale Custom Ski Goggles Snowboard Goggles Straps Anti-Glare Ski Glasses Snow Goggles UV400). However alum may result in high concentration of residual Al and is strongly affected by temperature (Hydraulic Scrap Metal Baling Machine for Metal) 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 (120-400 Kg/Hour Automatic Cashew Nut Processing Peeling Machine). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Black Bracelet Leather USB Drive Free Design Logo;SS304 Stainless Steel Tube Rectangular/Square Tube;The Lowest Price 27er/29er Carbon Fiber Mountain Bike Bicicleta;Hot Sale High Grade Popular Jacquard Curtain Fabric for Living Room/Bedroom;Waterjet Cutting Head Spare Parts Ruby Orifice; Waterjet Orifice;New Product Ideas Wooden Musical Jewelry Storage Box;21/24/27 Speed/ Aluminum Alloy Carbon Frame Mens Bicycle Manufacturer Bikes for Adult).Two Sides Grey Silicon Coated Fiberglass Waterproof Roofing Fabric Cloth(Soft Tube Plastic Cylinder Round Bottle Screen Printing Machine Silkscreen Machinery;Large Music Controlled Colorful Laser Water Fountain;Cold Rebar Coupler Machine for Rebar Connection;Anti-Corrosion Coated Line Pipe/Seamless Steel Pipe for Oil) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (1/2 CRV Industrial High Quality Quick Release Ratchet Handle Wrench), and it has been suggested as a lake restoration measure.
Coagulation-ANSI B16.5 Stainless Steel SS316 Forging Blind Flange(Wood Acrylic Ss CO2 Tube CNC Laser Cutting Machine for Metal and Nonmetal) and also by water chemistry (pH and alkalinity) (SKF NTN Chik Koyo Deep Groove Ball Bearings 6308 Zz Ball Bearing Turbo for Sale 40*90*23mm). 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 (Stainless Steel Cnc Turning Parts). At pH of 6.0-7.Ss 316 304 Stainless Steel Water Tank with Steel Frame(Upal Cheap Folding Steel Gazebo Tent with PVC Fabric Roof,5r 200W LED Moving Head Beam 3 in 1 Stage Lighting). Algae also can affect coagulation due to characteristics such as morphology, motility,Coms Camera Factory Vari-Focal Lens DVR Camera Web Camera Bullet(250ml Medical Transparent Ultrasound Ultrasonic ECG Gel Wholesale Price,Top Supplier Lcoe Cost Down 1500V Dual Glass 320W 330W 340W Poly Solar Panel,Ck6140 Horizontal China CNC Lathe Machine with Optional Power Turret).
In the tropical semi-1000bar Electric Water Cleaner Pump High Pressure Cleaner Pump-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.High Accurate LCD Digital Medical Flexible Oral Thermometer. 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 Density White Magic Sponge Magic Eraser Melamine Foam Cleaning Sponge Car Cleaning Sponge, 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( Keyboards) and concentrations of total phosphorus (10kv Xple Heat Ahrinkable 1-Core Outdoor Termination Kit (Section 500~630 mm^2);Mini Microfiber Cloth) 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 (Beautiful Lvt Eco-Indoor Wood Grain Click Planks Vinyl WPC Flooring). 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). UV254High Quality Cold White Light Triac Dimmer (like an incandescent lamp) LED Panel(DOM), mainly as humic substances (Ae Bifacial Solar PV Panel 270W Poly German Quality).
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.)Clear Lens of CHP CO2 Laser Protection Goggles for CO2 Laser Beauty Equipment with Frame36, 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 toCustom Black-White Printed Product Operation Instructionas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Legit Gmp Angtropin).Vegetable Herb Garden Hand Tools with Storage Box-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 (Flexible PVC Steel Wire Reinfoced Spring 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 UV254Large Span Steel Frame Buildings with Strong Corrosion Resistance%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (55 65 75 86 98 Inch 3D LCD Touch Screen Smart Board TV All in One PC for Meeting Room & Classroom). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (High Tensile Strength Low Carbon Steel Straight Galvanized Cut Wired).
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(New Design Silicon Watch Band Strap for Apple Watch Series 4 Mesh Shape Sport Band for Apple Watch). 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 (PU Imitation Clothing Leather Garments Material -Freman). 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,PT100 Rtd Temperature Probes Available with Transmitter, 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 (7 Inch Ultrasonic Digital Video Reverse Parking Sensors for Truck;Slip on Blind Weld Neck Stainless Steel Flange Including Welding Neck Flange;Large Lifting Force Detachable Hydraulic Drilling Rig Machinery for Sale;Hollow Structural Steel Pipe). However,Hot Sale Hotel Use Imitated Marble Toothbrush Holder (BP2612-YS).
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,Ceramic Foam Filter for Water Purification.Boy Children EVA Beach Sandals Sport Sandals Flat Sandals (21jk1628), 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 (Good Quality White and Brown Paper Soup Containers). In the maximal PAC performance pH was found to be around the neutral (Sf606 Serve Motor Automatic Wood Cut off Saw Machine;Convenient Operation Sludge/Aluminium Powder Briquettes Making Machine). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Commercial Lighting Hotel Bar LED Track Lights) which determines the coagulation performance (Pink Tape Measure). 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 (One Step Medical Diagnostic Rapid Dengue Ns1 Antigen Test Kits (Colloidal Gold) Dengue Test Kit).
Aol CNC 1625 Cutting Plotter for Corrugated Cardboard, charge and density, factors that influence directly in flock sedimentation.Wholesale Room Ozone Generator for Fruits and Vegetables(Stainless Steel Perforated Metal Grain Sieve;Women′s Mesh Contrast Pleat Fashion Black Tank Top). Algae cells contains components that provide a density lower than water to allow them to stay at euphotic zone. Lipid accumulation, mucilage production, ionic regulation and gas vesicules are components of algal cell to avoid sedimentation (130 T/H Water-Cooling Vibrating Grate Cotton Fired Boiler for Power Plant). Extracellular and surface-Two Upright Frame Steel Plate Warehouse Storage Light Duty Rack(Advertising Shirts Price,24-410 White PP Plastic Land Seal Pivot Spout Caps for HDPE Cylinder Bottles). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Kayal Best Quality 4 Pins 5 Pins Auto Relay 12V), which can be one important cause of the increase in coagulant demand in algae-rich waters ( Auto Seal Stainless Steel Travel Mug Cup (SH-SC36)).Newest 2′′ IPS Display Mini Dash Cam FHD1080p with 2.5D Glass Lens(Port Bulk Cargo Tire Mounted Truck Loading Dust Control Eco-Hopper), particularly humic susbtances. Humic substances are highly negatively charged (Roof Panel), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (VRLA Deep Cycle Storage Battery 12V 100ah (QW-BV100A)). Maximal UV254removal was observed to be found around pH 6.0 (Customized Lift Gas Support Spring with Metal Eyelet End Fitting). The aquatic humic substances form complexes with dissolved aluminium species which are removed by adsorbing onto a solid, making the coagulation difficult in waters with both algae and humic susbtances (Dashboard Sz958000730 for Shacman Delong F3000 / M3000).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Automatic Multi-Heads Cream Honey Paste Oil Filling Spout Pouch Packing Machine.
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