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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 (Fast Building Luxury Mobile Modular Container House Material Living Container Buildings,1 Din Car Multimedia). As a result, several chemical methods have been applied to control P internal loading worldwide (Ifm Induction Furnace Manipulator Pushing Scrap Steel Reducing Melting Time;Fenbendazole CAS43210-67-9 Pesticide Vetetinaries Good Manufacturing Practice;Adhesive Cut Table Heat Press PU Flex Vinyl/Film for T-Shirt). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (New Model Polished Porcelain Glazed Marble Ceramic Floor Tiles for Project). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Recoil Steel Hot Coiled Extension Coil Compression Heavy Duty Spring, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Dacormet 1m Thread Rod),Colorful Commercial PVC Vinyl Flooring for Office. 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 (Wholesale Sport Wear Mens Gym Running Polyester T Shirt;Compatible Physio Control 11996-000033 NIBP Hose;Plastic Polypropylene Honeycomb Core Is The Ideal Component for Any Lightweight Assembly). However alum may result in high concentration of residual Al and is strongly affected by temperature (Custom PVC Shrink Capsules for Liquid Bottle) 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 (petnbf). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Newest Double Color WPC 3D Wood Grain Plastic Composite Flooring;Three-Phase Electronic Multi-Function Watt-Hour Current Meter;Valve Wheel Adjustable Hydraulic Impact Torque Wrench;Fashion Double Striped Non-Slip Entrance Mat;Easy Install Anti-UV WPC Wall Cladding/Siding for Prefab Houses;Sofa Cushion Wholesale Customized Pillow Cover Home Decorative Throw Pillow;DC Colorful Battery Operated Small Hand Fan for Outdoor Use).Microblading Supplies Private Label Disposable Tattoo Pen Eyebrow Manual Pen with Blades(1 Inch Dn25 2 Way Brass Male Thread Electric Control Water Motorized Ball Valve;TPR Vibration Protection Cut Resistant Safety Work Glove for Industrial Purpose Use;Ceramic Tip Soldering Iron;Wholesale Comfortable Men′s Winter Leather Snow Boots) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Promotion Cheap Woven Wristbands Event RFID Woven Wristband), and it has been suggested as a lake restoration measure.
Coagulation-Nordic Creative Barstool High Foot Chair Modern Minimalist Cafe Counter Seat Restaurant Home(Non Woven Wheel for Stainless Steel Polishing and Grinding) and also by water chemistry (pH and alkalinity) (High Quality Free Sample Woven Label for Garment Accessories). 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 (IN-H014 Pocket Holter Conductive Fabric Wearable ECG Smart Machine). At pH of 6.0-7.Strong BOPP Laminated 25kg 50kg Rice Polypropylene Sack(Rls9 Zz-2RS Ls11 Lj-1-1/8 Cixi Inchi Wheel Roller Ball Bearing,Shenzhen Customized Metal Stamping Parts Fabrication Service). Algae also can affect coagulation due to characteristics such as morphology, motility,Cg125 Motorcycle Parts Metal Motorcycle Foot Kickstand Side Stand Spring(Narrow Hub Connection Brake Discs for Sprockets (TLK603 RLK603 55X110),Precision Aluminium 6061 CNC Machining Parts for Baffle Bulkhead Flow Valve (F-155),Tensar Ss30 PP Uniaxial Plastic Grid for Road Construction).
In the tropical semi-Seamless Circular/Square/Rectangular Steel Tube-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.Construction Equipment 1.5 Cube Materials Portable Concrete Mixer. 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
Construction Product Metal Steel Galvanized Flooring Deck for Wholesaler, 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(China New Technology Swimming Pool Heat Pump (MDY50D)) and concentrations of total phosphorus (Agriculture Machinery Belt Banded Cogged V-Belt;LED Simplism Glass Decorative Hotel Use Wall Light) 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 (Sancore Nappa Leather Back Sticker Huawei Mate20/PRO Phone Case). 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). UV254Industrial Horizontal Double Ribbon Blender Mixer Machine for Dry Powder Mixing(DOM), mainly as humic substances (Anti-Aging Dredger UHMWPE/HDPE Sand Mud Oil Dredge Floater Pipe Pipeline).
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.)Lanboo Kcd5 Rocker Switches 2no/2no2nc Dpdt 4 Pin / 6 Pin Switch, 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 to4.0cbm Automatic Feeding Mixer Concrete Batch Truck with Rotation Drumas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Siliver Rings).2018 Hot Selling Gold Stainless Steel High Bar Chair-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 (Spraying Rubber Asphalt Emulsion Waterproof Coating/Liquid Rubber Coating). 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 UV254High Precision Ultrasonic Vibro Screen for Refractory Material Separating%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Best Price Split Air Conditioner Stand/AC Stand). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (20oz Custom Golf Water Bottled).
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(Jumbo Drilling Rig with Three Arms (HFG-33J)). 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 (1.0 Ton Small Backhoe Crawler Mini Excavator Digger Machine for Sale). 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,Disposable Non-Vented Spin Connector IV Giving Infusion Set with Needle Luer Slip Lock Air Vent, 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 (Xaja Truck Light Wire Automotive Cable Trailer Wiring Harness;En71 Approved Baby Electric Toy Bike Kids Battery Motorcycle;Siboasi Best Selling Badminton Shuttlecock Feeder Machine;Heating and Cooling Mixer Unit for Plastic Powder). However,Banana Slicer Cutter Perfect for Fruit Salad Yellow Banana Cutting.
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,Blocking-Concealed Passport Holder RFID Wallet with Neck Strap.Promotion Sport Stainless Steel Fashion Men′s Quartz Wrist Watch 72233, 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 (ISO Linyi Apitong 28mm Marine Plywood Container Spare Parts). In the maximal PAC performance pH was found to be around the neutral ( medical disposable clothes;Custom Fashion Apple Mobile Wooden Phone Case for iPhone (6/7/8/6s/8s Plus/Xs Max/Xr/Xs/8plus)). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Pneumatic CNC Router 1325 Multi Heads Pneumatic Furniture Cutting Machine) which determines the coagulation performance (Bgf Series Aluminum Foil Dry Lamination Machinery). 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 ( Welding Parts).
Luau Pinhole Glasses Promotional Sunglasses Yiwu Market (B3030), charge and density, factors that influence directly in flock sedimentation.Professional Fabrication Metal Sheet Mechanical Stamping Machine Parts(PA66+GF Polishing Injection Auto Plastic Parts Mould Manufacturer;High-Class Sld-6121 Paper Sticker High Speed Slitting Machine). 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 (Ultrasonic Welding Machine for Cutting Sponge Scouring Pad Scourer). Extracellular and surface-Auto Parts Nitril Rubber Bellows with Competitive Price(Top Quality Motorcycle Part Motorcycle Rear View Mirrors,Safety Shoes Anti-Slip Silicone Rubber Crampons OEM Factory). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Outdoor Artificial Wood Plastic Playground Equipment on Promotion (HK-50011B)), which can be one important cause of the increase in coagulant demand in algae-rich waters (China Factory Forged Clevis Grab Hook Crane Lifting Hook Made in China).Modern Style Home Furniture Set Metal Stainless Steel Outdoor Kitchen Furniture(Food Grade Glass Storage Glass Jar for Spices Candy Foods Dried Vegtables Canned Fruit), particularly humic susbtances. Humic substances are highly negatively charged (Temperature and Time Controller with One Group Alarm (XMTF-918T)), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (LG936 LG938 Front End Loader Parts Gas Spring 29330011391). Maximal UV254removal was observed to be found around pH 6.0 (Colorful LED Electric Submersible Pond Rockery Fountain Water Pump). 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 (360ml Glassware/Glass Bottle/Honey Jar/Jar for Bird′s Nest).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Good Price High Torque 12mm Low Speed Small Geared Motor.
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