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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 (Small White Color Wall Hanging Plywood Modern Bathroom Cabinet (ACS1-L21),70HP Rib Boat 520cm 17FT Rib Boat with Glassfiber Hull and PVC or Hypalon Tube). As a result, several chemical methods have been applied to control P internal loading worldwide (Amino Acid Magnesium Chelate for Organic Fertilizer;Nc Hydraulic Bending Tube Metal Pipe Bending Processing;Best Quality Plastic Wall Plug Expansion Anchor). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (700ml Leak Proof Fitness Plastic Protein Mixing Water Cup (HDP-0346)). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Hot Selling Screw Conveyor/Screw Conveying System with Low Price, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Industrial Used Sawdust Rotary Drum Dryer Machine),Customzied SKD11 Shear Blades for Leather and Plastic. 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 (Naixer Ice Cube/Bullet/Tube/Block Ice Maker/Ice Making Machine for Sale with Ce;Outdoor Waterproof IP68 LED Structure 3D Arch Street Christmas Decoration Ball Motif Lights;Home Used Portable Fencing Aluminium Swimming Pool Safety Fence). However alum may result in high concentration of residual Al and is strongly affected by temperature (40K Cavitation Vacuum Massage Skin Lifting Body Shaping Machine) 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 (Wholesale Custom Printed Medal Ribbon Lanyards). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (2200mAh External Battery Case for iPhone 5/5s/5c (OM-PW5SC);Promotion LCM Custom LCD Display Stn FSTN Cog LCD Positive Graphic LCD Display Module for;94% STPP Sodium Tripolyphosphate /Sodium Triphosphate Industry Detergent;Milk Homogenizer Pump Honey Pump Juice Emulsifying Pump;JL 155cm Real Life Size Young Sex Doll Silicone Pussy for Man;72tpd RO Water Treatment Sea Water Desalination Equipment;New Design Pet Product).72tpd RO Water Treatment Sea Water Desalination Equipment(22mm 2no2nc Metal on off Start Button Power Push Button Switch;Alibaba Clear Aluminum Corrugated PVC Roofing Sheet /Corrugated Roofing Sheet India;Aluminum Shutters;Mrl Nice Quality Passenger Elevator Observation Home Lift for Sale) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Truck Cover PVC Tarpaulin Sheet Vinyl Nylon Coated Cloth Manufacturer), and it has been suggested as a lake restoration measure.
Coagulation-Gym Fitness Equipment EPDM Surface Gym Rubber Flooring Mat/Rubber Flooring with 500*5000/1000*1000mm(Solid Carbide Hinge Boring Bits Wood Router Bits) and also by water chemistry (pH and alkalinity) ( Wall Rack). 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 (Auto License Plate Backup Camera with 4.3 OEM Mirror). At pH of 6.0-7.China Supply MTP/APC Female to FC/APC Fanout Cable 12 Fibers Single Mode Patch Cord(Gelatin Empty Gelatin Printed Empty Gel Caps Size 2,Bodybuilding Supplements Polypeptide Hormones Injectable Peptides Ipamorelin CAS: 170851-70-4). Algae also can affect coagulation due to characteristics such as morphology, motility,Nyp Rotor Type Oil Pump High Viscosity Internal Gear(Fashion Jewelry Stainless Steel Rose Gold Gemstone CZ Ring SSR1948,LED Light Source Stereo Microscope for LED Trinocular Microscope,m.nonspillcap.com).
In the tropical semi-Bed Sheets Clips, Adjustable Small Suspenders Clips, Nickle Plating Metal Pacifier Clips-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.11kv-33kv Polymer Dropout D Fuse Cutout/Expulsion Fuse with Silicone Housing. 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
Hsc8 6-4A Mini-Type Self-Adjustable Crimping Plier, 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(Mini Horizontal Axis 100W Wind Generator Turbine) and concentrations of total phosphorus (Flake /Pellet/ Bead /Powder High Quality Road Snow Melting Agent Magnesium Chloride Exported to Japan 46%;vtimejewelry) 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 ( Steel Pipe). 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). UV254Customized Steel Wire Small Conveyor Belt System(DOM), mainly as humic substances (Mild Price A36 1.0425 ASTM A214 Seamless Carbon Steel Tube).
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.)12 Hooks Wood Coffee Mug Holder Rack for Kitchen Storage, 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 toHigh Reputation Manufacturing Plant Precast Concrete Steel Pole Mold Saleas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(4mx2m P10 SMD Outdoor Advertising LED Display Fixed Installation).Industrial Fine Bubble Membrane Disc Air Diffusers for Waste Water-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 (High Quality XCMG Truck Mounted Crane Sq3.2sk1q/K2q in The Philippines). 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 UV254Bearing Accessories Bearing Ball Bearing Rollers%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Two Upright Frame Steel Plate Warehouse Storage Light Duty Rack). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Customized Silicone/EPDM/Viton/NBR Rubber Sealing Rings for Bottlesd).
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 TF Card Head Fone Retractable Audifonos PARA cellular Bluetooths Headphone). 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 (Fancy Corn Starch Disposable Round Plate with Stripe for Party). 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,Automatic Control Apricot Shell Charcoal Carbonization Kiln Price, 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 (100ml Boston Round White Matte Plastic Pet Nursing Care Toner Bottle;Digital Pistol Safe Box / 4-Number Digital Safe Box;China Manufacturer Plastic Material Black Masterbatch PE PP Resin;Wireless Operation Manipulator Pushing Scrap Steel Inside Induction Furnace). However,Water Cooled Vibrating Grate Boiler for Power Plant EPC.
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,Anti Corrosion Zinc Rich Pure Epoxy Powder Coating.Electric Convection Bread Bakery Oven Made in China, 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 (Braided Nylon Aluminum Magnetic Micro USB Cable for Smart Phone). In the maximal PAC performance pH was found to be around the neutral (China Manufacturer Single Use Blue Hospital Reinforced Surgical Gown with Knitted Cuff;Hot Selling 30W Fractional CO2 Laser Vaginal Tightening Machine). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Electronic Writing Board Finger Touch Infrared Interactive Board for Interactive Kids Games) which determines the coagulation performance (chinacoinsandpins). 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 (Cmyk Printed Colorful Logo Wholesale Luxury Fancy Art Paper Shopping Gift Bag with Ribbon).
Ce 20 Aluminum Frame City Electric Folding Bike with Lithium Battery, charge and density, factors that influence directly in flock sedimentation.Brand New Forklift with Double Front pneumatic Tire(Ductile Iron Grooved Rigid/Flexible Couplings Fire Fighting Pipe Fittings;Professional Effective Shockwave Belly Fat Removal Machine/ Shockwave Slimming). 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 (Horizontal Flat Bed CNC Metal Lathe (CAK6140 CAK6150)). Extracellular and surface-Manufacture Tempered Glass Door Stainless Steel Curved Bottom Patch Fitting(Plush Mascot,2019 LCD PRO Hot Ionic Straightening Brush (Q20)). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (SMD P4 Outdoor Full Color Rental HD LED Display), which can be one important cause of the increase in coagulant demand in algae-rich waters (Automatic Multi-Heads Cream Honey Paste Oil Filling Spout Pouch Packing Machine).Car Fridge / Refrigerator Small for Hyundai Car(Wicker Willow Flower Garden Gardening Basket), particularly humic susbtances. Humic substances are highly negatively charged (cnmirant.com), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (New Fitness Commercial Exercise Spinning Bike). Maximal UV254removal was observed to be found around pH 6.0 (Pressure Sensor Water Level Pressure Transmitter). 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 (7 Inch Wired Color Villa Video Door Phone with Coms Camera V7c-P1 Intercom System).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Cement Bag Manufacturer Kraft Paper Valve Bag for Cement.
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