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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 (Baili Colorful Lights 500ml Aroma Scent Fragrance Diffuser,Waste Paper Egg Carton Production Line Egg Tray Machine). As a result, several chemical methods have been applied to control P internal loading worldwide (Fully Thread Square Neck Carriage Bolts DIN603 M6X35mm 304 Stainless Steel;2 Pin Waterproof Soldering Socket Waterproof Extension Cord Connectors;Auto Defrost Island Supermarket Freezer for Frozen Foods Display (RG-20)). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Kunlun Paraffin Waxes From Petroleum Made in China). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Gdg24 0.55kw 550W 0.75HP 24L Oil Free Air Compressor, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Nqg-5III Railroad Tools Internal Combustion Rail Cutting Machine),Tempered/Toughened Glass/Window/Shower Door Float Glass (T-TP). 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 (Ce Certificate Factory Provide Drink Water Vending Machine;Down Film Rolling Bag Wrapping Big Bread Packing Machinery 450X;CNC Machine Linear Guide Accordion Bellows Cover). However alum may result in high concentration of residual Al and is strongly affected by temperature (Metal Wire Mesh Knitting Scourer Machine with 220V 380V Voltage) 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 (Red Agate). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Brown Shoes High Quality Strong Protection Working Shoes;100% Pure PC Suitcase Luggage Aluminum Trolley Bags for Travel;School Exercise Book Making Machine 2.3.4 Colors;Syrup Piston Filling/Cream Liquid Bottle Filling Machine;Bemo Roof Standing Seam Roof Panel Roll Forming Machine/Standing Seam Roofing Sheet Machine;Bubble Cloth Seersucker Honeycomb Style Polyamide Knit Bikini Fabric;Plastic Tpd E Juice Bottle 10ml with Colorful Cap).3-Axle 30mt LPG Haulage Truck Trailer Depot Gas Transportation Tanker(LG953 LG956 LG958 Front End Loader Parts Sleeve/Bushing 29270001031;Fast Thermal Cycling High Heat Temperatures Resistance 99% Alumina Ceramic Insulator Rod;Oscillating Vibrating Knife Leather Cutting Machine for Genuine Natural or Artificial PU Leather;Digital Spirit Level Protractor Angle Gauge Meter Bevel Digital Inclinometer) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (IEC Standard FC APC PLC Splitter for Gpon Equipment), and it has been suggested as a lake restoration measure.
Coagulation-Best Factory Price Metallic Honor Medal with Neck Ribbon(Tablet Replacement Parts for Samsung Tab 3 Gt-P5200 LCD Assembly) and also by water chemistry (pH and alkalinity) (Low Price Promotional Concrete Cement Mortar Plaster Pump Machine). 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 (Crystal Violet Basic Dyes On Wood Wholesaler Quotes & PriceList). At pH of 6.0-7.Filter Press Machine for Sand Washer Sludge Dewatering Working Site in China(Easy Fans Eyelash Rapid Bloom Premade Volume Fan Lashes,Cabinet Base Work Table with Drawers and Sliding Doors). Algae also can affect coagulation due to characteristics such as morphology, motility,Custom Product Rapid Prototype Making/Vacuum Casting/CNC Machining Rapid Prototype(High Quality CNC Pipe Tube Fiber Laser Cutting Machine for Auto Silencer Muffler Use,Battery Crimping Tool for Pex-Al-Pex Multilayre/Copper/Stainless Steel Pipe,China High Pressure Hydraulic Hose Steel Wire Braided Rubber Hose R1 R2 1sn 2sn).
In the tropical semi-Poultry Farming Automatic Chicken Feeding Pan System-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.Water Resistant Rubber Gasket for Industry. 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
Truck Cover PVC Tarpaulin Sheet Vinyl Nylon Coated Cloth Manufacturer, 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(DMX New Design Stage DJ Disco 1024p Light Controller) and concentrations of total phosphorus (Promotion Stock Silicone Tea Infuser for Kitchenware;High Speed Planetary Gearbox) 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 (P10-32X96 Yellow U-Disk Control Outdoor Waterproof LED Display Screen Picture or Text Can Be Edited). 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). UV254PVC Gas Hose, LPG Hose Best Choice for Home Use(DOM), mainly as humic substances (Outdoor Food Meal Heating Bag for Travelling and Camping).
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.)Rectangle Deep Cake & Bread Baking/Bake/Roasting Pan, 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 to Dooras they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Shield Tunnel Lining Segment Mould).Home Furniture Soft Foam Latex Pocket Spring Foam Encased Mattress-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 ( LPG Hose Best Choice for Home Use). 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 UV254Best Polystyrene Sandwich Board Manufacturer%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (High Performance Electroplated Diamond Wire/Steel Wire/Diamond Wire). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Natural Health Probioticsd).
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(10 Axis 3D CNC Heavy-Duty Metal Wire Bending Forming Machine). 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 (Bright Solar Power Outdoor LED Light Motion Activated Light for Garden Patio Path Pool). 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,Outdoor WPC Wood Plastic Composite Fence Board with High Quality, 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 (Custom Lf 125kHz/Hf 13.56MHz Pet/PVC RFID Contactless Smart Card with Cheap Price;Supporting DDR4 RAM Intel Core I5 Mini PC Computer;Vodafast A2 Stainless Steel Channel Nuts with Long Spring;Factory Supply Easy to Install WPC Wall Panel for Interior Decoration). However,Full Automatic Chocolate Holding Tank with Water Jacket.
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,Professional Supplier of Hot Rolled Steel U Channel.22mm 2no2nc Metal on off Start Button Power Push Button Switch, 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 (Double Glazing Equipment Automatic Desiccant Filling Machine Insulating Glass Machine). In the maximal PAC performance pH was found to be around the neutral (Custom Aluminum Stainless Steel 90 Degree Angle Brackets;5kw 12V/24V/48V/DC to AC/110V/120V/220V/230V/240V Pure Sine Wave Solar Power Inverter). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Aluminum/Cooper/Galvanized Tube Precision Pipe Making Machine) which determines the coagulation performance (Cruise ship). 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 (4mm Sheet Metal Bending Machine 100ton Plate Bending Machine with Da52s).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.19 Inch Australia Type Universal Socket Network Cabinet and Rack PDU.
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