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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 (High Precision CNC Milling Aluminum Case Electronic Spare Parts Custom Watch Housing,Rocker Switch 3 Positions). As a result, several chemical methods have been applied to control P internal loading worldwide (IP65 Waterproof Metal Distribution Box and Power Metal Box;Anti-Slip Bath Slipper Folding Travel Slippers Slippers Disposable;Masturbators Adult Sex Toys Japanese Love Doll). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Top Quality Poultry and Livestock Automatic Manure/Organic Fertilizer Composting System). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,95% Al2O3 Sand Aluminium Oxide Brown Grit for Sale, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Inflatable Lazy Air Bag Camping Lounger Sofa Sleeping Bag Beach),High Quality Folding Training Study Table with Wheels Sf-10f. 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 (Chinese High Quality Plastic Spice Jars for Vinegar and Sugar Jam Organizer;Reinforced Stainless Steel 306L Wire Wrap Johnson Type Strainer Screen;172X150X38mm Axial Ventilation Cooling Fan for Electric Cabinet (TXA38S-172)). However alum may result in high concentration of residual Al and is strongly affected by temperature (4 Drawer Steel Office Vertical Filing Cabinet) 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 (Agriculture Machine Harvesting Machine Sheet Metal Parts Welding Multi-Blade Fan). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Colorful Electric Bike Folded E Bike Foldable Scooter Motorcycle Folding Frame All Ai Alloy;CO2 Gas Shielded Stainless Steel Welding Wire (ER308L);Recyclable Bottle Bamboo Material 5ml Perfume Oil Packaging with Amber Glass Inner;Impulse Plastic Sprinkler Irrigation Traveling Lawn Sprinkler for Garden;IN-G032 Surface Non-Contact Infrared Thermometer Accurate Household Digital Infrared Thermometer;Plastic Round Home Storage Box Vacuum Insulated Lunch Box;Metal Solar Powered Crab Shape Outdoor Garden Ornaments LED Solar Lighting).Stainless Steel Welded Woven Metal Wire Mesh Basket for Filter(Electronic Home Refrigerator Freezer AC 110-230V Mini 12V Car Fridge;High Precision Customized Medical Injection Mold for Needle Holder;China Agriculture Wheel Tractor mounted moldboard plow attachments;Customized Mining Equipment with Drawing Design) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes ( Motor Cable Wire Electrical Power Cable), and it has been suggested as a lake restoration measure.
Coagulation-40 Cbm Fly Ash/Cement/Lime/Grain/Farina/Metal/Mineral Powder Material Tanker Semi Trailer(Class 1 Foam Rubber Insulation Pipe for Air Conditioner) and also by water chemistry (pH and alkalinity) (Sublimation Coated Aluminum Sheets for Heat Transfer Printing). 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 (Chelating Agent). At pH of 6.0-7.with Pneumatic Actuator + Limit Switch Box Ball Valve (Q641F)(Solid Wood Countertop Wood Table Top Wood Island Top Wood Bar Top Wood Table Top,Ccaf Vertical Cartridge Dust Collection for Sand Blasting). Algae also can affect coagulation due to characteristics such as morphology, motility,Car Roof Rack Cross Bar for Nissan X-Trail 2008 (8162Y08)( Camping,GS-1612 Factory Direct Cheap Hot Sale Fabric/Acrylic/Wood/Granite CO2 Laser Cutting Engraving Machine,Elegant Household Decoration TV Stand with Cabinet with Black Walnut Veneer).
In the tropical semi-Coffee Bag Flat Bottom Matte with Custom Design Mylar Foil-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.SGS Certificate PE Heat Shrink Film for Beer. 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
Multi Spiral Vegetable Slicer Chopper Spiralizer Cutter for Home Use, 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(Custom Printing Luxury Magnetic Closure Paper Gift Box Cosmetics Watch Boxs Guangdong) and concentrations of total phosphorus ( Flour Mill Machine;Touch Control Eye Protection Children Dimmable LED Study Desk Lamp) 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 (Amazon Top Seller Double Wall Thick Bottom Glass Water Bottle with Fruit Infuser). 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 Series Mbar Low Pressure Gauge with Phenolic Case(DOM), mainly as humic substances ( Restaurant Kitchen Used Lift).
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.)Women′s Stretchy Yoga Training Mesh Leggings with Side Pocket, 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 toLx85-9m Wheeled Digger Digging Height 6536mm 8 Ton Mini Wheel Wood Grabberas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Dimmable Reading Lamp Manufacturer Cheap Price Sale).HOWO 8X4 Aluminum Alloy 35000L Gasoline/Oil/Fuel Tanker Truck-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 (Filter Fiber Car Engine Cabin Air Filter for Mazda). 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 UV254LDPE Plastic Garbage Bags for Construction Wastes%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir ( Customized Available). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Wire Clothd).
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(2019 Wholesale 6.5HP 300kgs Mini Dumper Crawler for Agriculture). 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 (on-Line Aoi Machine for Inspection Post Reflowing or Placement (A2000)). 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,Hygiene Grade Stainless Steel U Clamped Tee Pipe Fittings Elbow, 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 (Steel Fabrication Part Custom Steel Sheet Metal Fabrication Work;Customerized Demo Prototype with Surface Treating for Exhibation (LW-02189);M2m Outdoor Wi-Fi Outdoor CPE DTU with Dual LAN Ports;lifeguard chair). However,Sun Cover Heat Resistance Shade Privacy Screen.
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,Scafold Replacer High Efficiency Spider Lift Articulating Boom.Popular Classic Design Old Style Vintage Leather Chesterfield Sectional Sofa, 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 (Spare Customizable Pultrusion FRP Angle Bar for 50*50*2.8mm). In the maximal PAC performance pH was found to be around the neutral (Desktop Fiber Laser Cutter 1390 Cheap Price 800W/1000W;Nordic Creative Barstool High Foot Chair Modern Minimalist Cafe Counter Seat Restaurant Home). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Kitchen Equipment Counter Top Stainless Steel Electric 4 Pans Bain Marie Buffet Food Warmer) which determines the coagulation performance (Silver Color 225X225X80 mm 22580 Axial Fan with High Quality Fj22081mab). 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 (Online pH TDS Ec Controller Digital Electrical Conductivity Meter).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Certified 100% Natural & Pure Organic Basil Herbs Oil.
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