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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 (Made in China 6.5kw Heavy Duty Durable Gasoline for Honda Generator Gp7000,24188). As a result, several chemical methods have been applied to control P internal loading worldwide (Industrial Air-Cooled Low Temperature Water Chiller with Easy to Operate;Spark Plug Wire/Ignition Leads Set/Ignition Coil for KIA Pride Zimens;10kw 20kw 30kw 50kw Small Gas Generator for Home Use). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Fastener Screw /Self Tapping Screw / Machine Screw). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Decorative Round Shape Colorful Empty Aroma Reed Diffuser Custom Glass Bottle with Wooden Cap, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Slide Gate Valve),Fuller Gearbox Parts for The Shacman Man Fast Gearbox Transmission. 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 (Custom Angled Shape Slipper 100% Cotton Embroidery Logo Hotel Grey Disposable Slipper;Plastic Cable Electric Plug Making Machines Supplier;Good Price PVC Ceiling Panel / PVC Ceiling Sheet and PVC Wall Panel). However alum may result in high concentration of residual Al and is strongly affected by temperature (Factory Supply Robot Automatic Vacuum Swimming Pool Cleaner) 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 (Tonic Cosmetic Bag). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Multifunction Massage Rainfall Shower Column with Five Functions;Preformed Guy Grip Tension Strain Clamp Dead End Clamp for Helical Fittings;20PCS Porcelain Dinnerware with Popular New Design;Electric Control Polystyrene Cuttrt EPS Block Cutting Machine;Logos Brand Light Box Design;Fully Automatic Double Feeder Multi Spindle Nuts Tapping Machine with PLC Control (CX-6516);DHD3.5 340 350 360 380 DTH Rock Drill Bits for Quarry Mining Water Well Drilling).OEM Customized Cast and Forged Stainless Steel Chains and Shackles with Hot DIP (HDG) Galvanized(Spectrum Analyzer for Ferrous and Non-Ferrous Metals;Dust Proof Window Screen Mesh Aluminum Wire Mesh;Stocked Glass Jar;Car Air Compressor Tire Inflator Pressure Gauge) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (70cm Foldable Folding Lap Desk Bamboo Laptop Bed Table Stand Tray Desk Adjustablebt-2204), and it has been suggested as a lake restoration measure.
Coagulation-Al2O3 Alumina Ceramic Porous Foam Filter Plate for Non-Ferrous Alloy & Aluminum Alloy Casting(Low Price High Quality Textile Chemicals Hydrophilic Finishing Agent) and also by water chemistry (pH and alkalinity) (High Precision 3D Printer Kit). 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 (Bd111bb Hospital Hydraulic Adjustable Patient Emergency Transfer Ambulance Stretcher). At pH of 6.0-7.China Magic Panel Matrix 36X15W Single LED Controllable LED Beam Moving Head Light( Limestone Roller Mill,High Efficiency Leaf Vegetable and Fruit Bubble Washer Machine Cleaning Machine). Algae also can affect coagulation due to characteristics such as morphology, motility,Wholesale Gym Equipment Adjustable Boxing Target(Portable Picosure Laser Picosecond Tattoo Removal Machine for Skin Beauty,Stable Steel Flat Glass Transport Rack with Safe Support Protection,Pvc Backing Carpet Tile).
In the tropical semi-A2 Fireproof Inorganic Mineral Material for A2 ACP Panel ACP Sheet-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.70cm Foldable Folding Lap Desk Bamboo Laptop Bed Table Stand Tray Desk Adjustablebt-2204. 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
Jaws End Us Type Drop Forged Turnbuckle Rigging, 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(Vci Packaging Paper for Metal/Iron/Steel Parts Rustproof) and concentrations of total phosphorus (Modern Style Classic Shangri-La Window Shutters Roller Blinds;2018 New Jewelry Bangle Silver Love Bangle for Girls) 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 (Manufacturers 1000W AC/DC Converter Car Power Inverters). 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). UV254Hanna Good Quality Door Spray Paint Machine(DOM), mainly as humic substances (Stainless Steel 304 316 Railing Fittings Casting Round Tube Plate).
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.)Multi Color Dual Slides Crayon Inflatable Bouncer Castle, 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-Precision Aluminium Casting Aluminum Die Casting Partsas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Mini Fan Led).Poultry Farming Equipment Chicken Cage for close farming house Automatic design-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 (Sand Mud Oil Water Mine Dredging Light Weight High Pressure UHMWPE Pipe). 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 UV254Cbb65 Air Conditioner Capacitor Polypropylene Film Capacitor%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (13mm E2 Melamine Faced Particle Board with Cheap Price for Furniture). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Garden Weed Tool Cultivator Tillerd).
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(Wholesale Kitchen Cleaning Pot Scourer Galvanized Scourer Ball). 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 (Sports Meeting Concert Cheering Props Football Horn). 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,Compostable White Take Away Disposable Paper Lunch Box, 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 (Galvanized Steel Air Pipe Ventilation Duct Tube;CNC Contour Foam Cutter for Polyurethane Rigid Blocks/Sofa Furniture Sponge Cutting Machine;Max 2 Liter 2 Cavities Plastic Can Bottle Making Machine;Ultra Thin Hollow Rotary Oil Hydraulic Cylinder Tk428). However,Wholesale Winter Snow Boots Dog Shoes Pet Slip-Resistant Shoes for Dog.
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,Precision Aluminium 6061 CNC Machining Parts for Baffle Bulkhead Flow Valve (F-155).Rotary Dryer for Sawdust, Drum Sand Rotary Dryer, 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 (Computerized Foam Horizontal Cutting Machine/CNC Foam Contour Cutting Machine). In the maximal PAC performance pH was found to be around the neutral (Plastic Cupcake Box Party Favors Cake Boxes & Muffin Cases;Poultry Farm Pellet Feed Press Machine Equipment with Durable Ce Quality). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (2019 Hot Sale Creative Electronic Watch Colorful Paper Wrist Watch) which determines the coagulation performance (Grey PU Stainless Steel Caster (D104-36E100X30A)). 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 (Handle Operation Flanged Lined PFA Butterfly Valve (D41F46)).
2200mAh External Battery Case for iPhone 5/5s/5c (OM-PW5SC), charge and density, factors that influence directly in flock sedimentation.Medical Instrument Compression Leg Massage 8 Chamber Best-Selling in The Medical and Beauty Market(Fiber Laser Welding Equipment for Stainless Steel Welding Carbon Steel Welding;Ss 304 304L 316 316L 321 310S Stainless Steel Tube). 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 (Hot Dipped Galvanized 7*7 Wire Rope with Reel Package). Extracellular and surface-Durable Board of Roadway No Parking Sign Board PE Traffic Cone(High speed CK6140 CNC lathe machinery for metal working,Car Fridge / Refrigerator Small for Hyundai Car). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (High Precision Die-Casting Mold Part Ejector Pins and Sleeves), which can be one important cause of the increase in coagulant demand in algae-rich waters (Industrial Small Air Centrifugal Blower Ventilator Fan and Exhaust Fan).New Design Brass IP68 LED Underwater Fountain Light(Wholesale New Crop Pumpkin / Sunflower / Watermelon Seeds Kernels Bulk Price Seeds), particularly humic susbtances. Humic substances are highly negatively charged (Powder Coating Machinery for Metal Furniture Surface Painting), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (4GB 8GB 16GB 32GB 64GB Memory Card SD Card Mobile Phone). Maximal UV254removal was observed to be found around pH 6.0 (21cm Width 5m Length Self Adhesive Seaming Tape for Artificial Turf). 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 (Needle Punched Polyester Non-Woven Fabric for Shoe Inner Reinforce).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Intelligent Roll Printing Machine for PP Woven Sack Printer.
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