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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 (13.56MHz Logo Printing Mini NFC Epoxy Card for Access System,Hot Selling 9V Li-ion 650mAh Battery 9 Volt Li-on 8.4V Rechargeable Lithium Battery). As a result, several chemical methods have been applied to control P internal loading worldwide (PPGI/PPGL Prepainting Galvanized Steel with Ral Color;Book Matched Marble Tiles Wall Design in Hotel Hall Natural Blue Macubas Marble Slab;Highway Outdoor Road Integrated Solar LED Street Light Price List). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Glacial Acetic Acid Tech Grade and Food Grade Glacial Acetic Acid). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Low Factory Price UHP Graphite Electrode Used for Steel Making, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Chain Link Fence Machine Wholesaler Quotes/PriceList),Wallbox Socket Type 2 16A 3.7kw Single Phase EV Charging Point EV Charger for Electricvehicles. 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 (Light Weight Concrete AAC Brick/Block Making Machine for Wall Material;Commercial Automatic Ultrafine Air Jet Mill for Sale;Thickness 140 Micron Pharmaceutical Cold Forming Blister Aluminum Foil). However alum may result in high concentration of residual Al and is strongly affected by temperature (Wiskind Fireproof Hydrophobic Waterproof Rock Wool/Glass Wool Sandwich Panel) 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 (Telescopic Wheel Loader 2 Tons Lifting Capacity with CE). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Sewage Pipeline Detection Robot with Strong Driving Force;Multi-Function Solar Power Generation System for Remote Areas;Sj Good Price Plastic PE Pipe Making Extrusion Extruder Machine;Weight Loss Equipment with Cryolipolsis Fat Freezing 40K Cavitation Rflipo Laser;Ipak to-251 Package Golden Testing Contact Finger with Factory Price;Baili Colorful Lights 500ml Aroma Scent Fragrance Diffuser;Fully Thread Square Neck Carriage Bolts DIN603 M6X35mm 304 Stainless Steel).Kindergarten Themes Children Furniture Sets Classroom Adjustable Baby Chair(2 Pin Waterproof Soldering Socket Waterproof Extension Cord Connectors;Auto Defrost Island Supermarket Freezer for Frozen Foods Display (RG-20);Large Commercial and Industrial Dust Mops for Gym and Hotel Use;Kunlun Paraffin Waxes From Petroleum Made in China) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Ce Certificate Factory Provide Drink Water Vending Machine), and it has been suggested as a lake restoration measure.
Coagulation-Economic Wholesale Blank Stretched Canvas(Down Film Rolling Bag Wrapping Big Bread Packing Machinery 450X) and also by water chemistry (pH and alkalinity) (CNC Machine Linear Guide Accordion Bellows Cover). 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 (5.5 Mm Ball Bearing). At pH of 6.0-7.OEM Design 24 & 30 Cavities Cold Runner Spoon Mould(Metal Wire Mesh Knitting Scourer Machine with 220V 380V Voltage,Brown Shoes High Quality Strong Protection Working Shoes). Algae also can affect coagulation due to characteristics such as morphology, motility,Shinco 10′′ Portable Bluetooth Wireless Mobile Theater Trolley Speaker(100% Pure PC Suitcase Luggage Aluminum Trolley Bags for Travel,School Exercise Book Making Machine 2.3.4 Colors,Beverage Showcase).
In the tropical semi-800W One Wheel Electric Self Balance Motor Scooter Hoverboard with APP Controller-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.HOWO 12cbm Asphalt Spraying Truck Bitumen Sprayer Tank Truck Distributor Road Construction Machinery. 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
High Quality Medical Disposable Pen Type Blood Collection Needle, 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(Plastic Tpd E Juice Bottle 10ml with Colorful Cap) and concentrations of total phosphorus (LG953 LG956 LG958 Front End Loader Parts Sleeve/Bushing 29270001031;Portable Air-Conditioning Table Office Fan Electric USB Desk Mini Fan) 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 (IEC Standard FC APC PLC Splitter for Gpon Equipment). 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). UV254High Quality Precision Aluminum Automatic Lathe CNC Machining Parts(DOM), mainly as humic substances (Tablet Replacement Parts for Samsung Tab 3 Gt-P5200 LCD Assembly).
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.)High Efficiency Leaf Vegetable and Fruit Bubble Washer Machine Cleaning Machine, 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 Quality CNC Pipe Tube Fiber Laser Cutting Machine for Auto Silencer Muffler Useas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Square Rhinestones).Jy-GB20 Hard Paper Perfume Storge Paper Cosmetic Box-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 (Hot Dipped Galvalume Steel/Aluzinc Steel with Anty-Finger). 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 UV254Self Leveling Flow Mortars Additives Vae Redispersible Polymer Powder%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (DMX New Design Stage DJ Disco 1024p Light Controller). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Door Moulding Packaging Box Corrugated Cardboard Endless Z-Folding Cardboardd).
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(1.2344/AISI H13/8407 Stainleess Steeel for Thread Rolling Die). 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 (Non-Toxic and Corrosion-Resistant PVC Pipe for Drinking Water). 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,Precision CNC Turning Milling Machine Part for Auto Equipment, 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 (Artificial Push up Breathable and Strapless Adjustable Invisible Silicone Bra;Top Quality Vehicle GPS Tracker with Fuel Cap Sensor M508;430 Black Mirror Decorative Stainless Steel Sheet in Foshan;Liquid PVC Rubber Shoe Base Dripping Machine). However,Manufacturer Price High Strenghth HDPE Garbage Bag.
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,Factory Supply Good Quality PVC Vinyl Gypsum Ceiling Tiles.Decoration Building Material Prepainted Corrugated Galvanized Roofing Sheet Steel Plate, 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 ( Door). In the maximal PAC performance pH was found to be around the neutral (Square Shape Glass Perfume Bottle Refillable Glass Perfume Bottle Atomizer Mist Bottle;Atex Approved Level Measuring Instrument Level Sensor). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation ( LPG Hose Best Choice for Home Use) which determines the coagulation performance (Pipe Cutting). 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 (High Performance Electroplated Diamond Wire/Steel Wire/Diamond Wire).
Water Microdermabrasion Hydro Facial Machine for Acne Removal Skin Revitalizer, charge and density, factors that influence directly in flock sedimentation.Bicycle Parts Steel Bike Repair Stand Display Rack (HDS-004)(Wholesale Foldable Desk Silicon Mobile Phone Stand;10 Axis 3D CNC Heavy-Duty Metal Wire Bending Forming 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 (Bright Solar Power Outdoor LED Light Motion Activated Light for Garden Patio Path Pool). Extracellular and surface-Wet and Dry Vacuum Cleaner SL18125p 1gallon /4litres 1.5HP Portable Poly Stanley(Cheap Super Soft Sheet, Table Gas Stove). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (API-5CT Standard Seamless Steel Pup Joint /Oilfield Services), which can be one important cause of the increase in coagulant demand in algae-rich waters (Custom Lf 125kHz/Hf 13.56MHz Pet/PVC RFID Contactless Smart Card with Cheap Price).Modern Style Prefabricated Steel Structure Poultry House(Supporting DDR4 RAM Intel Core I5 Mini PC Computer), particularly humic susbtances. Humic substances are highly negatively charged (Hydraulic Hoist), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Vodafast A2 Stainless Steel Channel Nuts with Long Spring). Maximal UV254removal was observed to be found around pH 6.0 (Double Glazing Equipment Automatic Desiccant Filling Machine Insulating Glass Machine). 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 (Custom Aluminum Stainless Steel 90 Degree Angle Brackets).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Made in China Colored Heat Resist Strength Silicone Rubber O-Rings for Excavator.
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