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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 (Wireless Data Acquisition and Lora Gateway with Multiple Channels for Remote Monitoring,Fiberglass Honeycomb Sandwich Panel Gel Coated FRP Sandwich Panels Fo Vehicle Body). As a result, several chemical methods have been applied to control P internal loading worldwide (Cheaper Polyester Cord Strap Factory Made in China;AC 400V Vector Control Frequency Inverter 18.5kw for Textile Machine;Automatic Dry and Wet Pig Feeder for Pig Feeding Equipment). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Special Flower Shaped Sterling Silver Cubic Zirconia Earring for Lady Wedding Gift). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,High Quality Folding Training Study Table with Wheels Sf-10f, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (China Led Lighted Telescopic Inspection Mirror),Stainless Steel Welded Woven Metal Wire Mesh Basket for Filter. 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 (CNC Machining Part CNC Turning Stainless Steel Parts Aluminum CNC Milling;Good Price and High Quality Crawler Crane Excavator Bearing;Three Layers ABC Co-Extrusion PP Film Blowing Machine). However alum may result in high concentration of residual Al and is strongly affected by temperature (Aluminium Silver Lifter 230kg Suction Heavy Duty Suction Cup Hand Tool for Glass) 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 (Cheap Waterproof Vinyl Die Cut Custom Stickers with Logos (jp-s172)). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Galvanized Razor Barbed Wire with Ce and SGS for Livestock Farm;Kaishan YT23D Forging Air Leg Support Rock Drill Machine;High Polished Solid Egypt Sunny Beige Marble Columns;Multi-Functional Universal Mount LED Brake/Turn/Tail Lights;Maternal and Child Room Safety Seat Baby Care Chair Foldable;Natural Color of 100% 7A Malaysian Human Hair;49 Electric/Electrical Synchronous AC Gear Motor for Stage Light/Oven).40 Cbm Fly Ash/Cement/Lime/Grain/Farina/Metal/Mineral Powder Material Tanker Semi Trailer(New Design Brass IP68 LED Underwater Fountain Light;Plastic Nozzle 360 Rotary Kitchen Faucet Shower Head Economizer;Non Woven Bag Polypropylene Suppliers for Sale;China Supplier Seamless Carbon Steel Pipe for Motorcycle Parts with 1010) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (2 in 1 Mini Qi Fast Pad for Apple Watch 1 2 3 4 Series Airpods Wireless Charger), and it has been suggested as a lake restoration measure.
Coagulation-with Pneumatic Actuator + Limit Switch Box Ball Valve (Q641F)(OEM Production Fancy Folding Paper Window Gift Boxes) and also by water chemistry (pH and alkalinity) (Toroidal Power Transformer for Household Audio). 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 (Gymnastics Training Equipment). At pH of 6.0-7.Car Roof Rack Cross Bar for Nissan X-Trail 2008 (8162Y08)( Tiger Skin Yellow Cement Based Wall Stone Veneer,Watertight Hi-Viz Yellow Thermal Latex Gloves Safety Work Glove). Algae also can affect coagulation due to characteristics such as morphology, motility,Coffee Bag Flat Bottom Matte with Custom Design Mylar Foil(Hot Sale Industry Titanium Disc/Titanium Alloy Disc,Android Handheld Barcode Scanner Industrial PDA,Pet Packing Strap PP Strapping Band Extrusion Line Pet Belt Producing Machine).
In the tropical semi-SGS Certificate PE Heat Shrink Film for Beer-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.Multi Spiral Vegetable Slicer Chopper Spiralizer Cutter for Home Use. 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
Industrial Series Mbar Low Pressure Gauge with Phenolic Case, 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(Easy Maintenance Automatic 6000PCS/H Egg Tray Machine) and concentrations of total phosphorus (New selling OEM quality strong magnet segment arc ferrite magnet for motor;25m3/H Skip Type Stationary Small Concrete Batching Plant) 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 (50-500μ M Pet Film for Electrical Insulation (6023D)). 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). UV254Women′s Stretchy Yoga Training Mesh Leggings with Side Pocket(DOM), mainly as humic substances (Manufacturer Bimetallic Parallel Twin Screw Barrel for Extruder).
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.)HOWO 8X4 Aluminum Alloy 35000L Gasoline/Oil/Fuel Tanker Truck, 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 to18.5 Pct Capacitive Touch Screen Monitor Open Frame Design Interactive Displayas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Disc Chain Conveyor).LDPE Plastic Garbage Bags for Construction Wastes-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 Cheap Hygienic Grade Sap Sodium Polyacrylate for Cooling Packing). 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 UV254Hygiene Grade Stainless Steel U Clamped Tee Pipe Fittings Elbow%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Nonwoven Polyester Fiber Pillow Making Plant (ZXJ-787)). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Aluminum Foldable Children′s Two Wheels Scooter with Lightedd).
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(Super Cool Hotel 100GSM Drawstring Black Non-Woven Laundry Bag). 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 (Private Label Washing Laundry Powder Detergent). 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,Sun Cover Heat Resistance Shade Privacy Screen, 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 (Fashion Design Steel-Wood Large Conference Table;Balaclava Hood Ski Bike Cycling Face Mask Cap Fleeces Helmet;Easy to Use Mobile Filter Unit for Light to Medium Welding;74% Calcium Chloride Prill Suppliers for Sale). However,Scafold Replacer High Efficiency Spider Lift Articulating Boom.
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,Popular Classic Design Old Style Vintage Leather Chesterfield Sectional Sofa.1500 W /2000 W Disabled Electric Tricycle with Double Seat, 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 (8FT Face Veneer Rotary Peeling Lathe for Wood Log Cutting Line). In the maximal PAC performance pH was found to be around the neutral (Dry Ice Production Block Cube Maker Producer Refrigeration Industry Use Machine;Best Seller Canvas Striped Cotton Rope Fabric Hanging Hammock). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Topkit Tower Crane Rct6011-6 for Construction Building) which determines the coagulation performance (www.nbzkls.com). 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 (Motion Sensor Light Stick Closet Light Wall LED Night Light).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.12oz Dispossable Ripple Wall Paper Cup with Good Insulation.
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