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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 (Battery Crimping Tool for Pex-Al-Pex Multilayre/Copper/Stainless Steel Pipe,Warehouse Storage System Radio Shuttle Steel Pallet Rack). As a result, several chemical methods have been applied to control P internal loading worldwide (10inch Tire Two Wheel Self Balance Electric Scooter;Hot Dipped Galvalume Steel/Aluzinc Steel with Anty-Finger;DMX New Design Stage DJ Disco 1024p Light Controller). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Promotion Stock Silicone Tea Infuser for Kitchenware). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Cylinder Borosilicate Glass Cooking Oil Bottle with Spout, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (New Intelligent Program-Controlled Basketball Practise Shooting Machine),11oz Heat Transfer Sublimation Hot Water Change Color Magic Mug (Matte). 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 (1.2344/AISI H13/8407 Stainleess Steeel for Thread Rolling Die;Non-Toxic and Corrosion-Resistant PVC Pipe for Drinking Water;P10-32X96 Yellow U-Disk Control Outdoor Waterproof LED Display Screen Picture or Text Can Be Edited). However alum may result in high concentration of residual Al and is strongly affected by temperature (Outdoor Food Meal Heating Bag for Travelling and Camping) 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 (Antibacterial Bamboo Cutlery). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (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; Door;Flake Ice Maker;Square Shape Glass Perfume Bottle Refillable Glass Perfume Bottle Atomizer Mist Bottle;Atex Approved Level Measuring Instrument Level Sensor).Hot Selling SAA Rcm Listed CCT Changeable LED Down Light( LPG Hose Best Choice for Home Use;High Performance Electroplated Diamond Wire/Steel Wire/Diamond Wire;Robotic Bus/Truck Wash Machine/Car Washing Machine with Super Big Brushes;Wholesale Foldable Desk Silicon Mobile Phone Stand) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (10 Axis 3D CNC Heavy-Duty Metal Wire Bending Forming Machine), and it has been suggested as a lake restoration measure.
Coagulation-Ferrous Sulphate Heptahydrate for Water Treatment(Bright Solar Power Outdoor LED Light Motion Activated Light for Garden Patio Path Pool) and also by water chemistry (pH and alkalinity) ( Table Gas Stove). 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 (HDF Lamiante Floor Home and Office Wood Laminate Flooring). At pH of 6.0-7.Factory Made Pneumatic Adjustable Gas Piston 600n for Garden Chair(API-5CT Standard Seamless Steel Pup Joint /Oilfield Services,Custom Lf 125kHz/Hf 13.56MHz Pet/PVC RFID Contactless Smart Card with Cheap Price). Algae also can affect coagulation due to characteristics such as morphology, motility,NF3, Nitrogen Trifluoride, Liquid Gas, 99.99~99.999%(Supporting DDR4 RAM Intel Core I5 Mini PC Computer,Vodafast A2 Stainless Steel Channel Nuts with Long Spring,Precast Concrete Segment Mould).
In the tropical semi-Recoil Steel Hot Coiled Extension Coil Compression Heavy Duty Spring-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.Colorful Commercial PVC Vinyl Flooring for Office. 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
Microblading Supplies Private Label Disposable Tattoo Pen Eyebrow Manual Pen with Blades, 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(5kw 12V/24V/48V/DC to AC/110V/120V/220V/230V/240V Pure Sine Wave Solar Power Inverter) and concentrations of total phosphorus (Aluminum/Cooper/Galvanized Tube Precision Pipe Making Machine;High Quality Rectangular Carbon Rod/Electrode B5520) 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 (Outdoor WPC Wood Plastic Composite Fence Board with High Quality). 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). UV254Nordic Creative Barstool High Foot Chair Modern Minimalist Cafe Counter Seat Restaurant Home(DOM), mainly as humic substances (Fiberglass Water Park Spray Playground Equipment for Sale).
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.)Strong BOPP Laminated 25kg 50kg Rice Polypropylene Sack, 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 toRuizhou Auto Feeding Laser Fabric Cutting Machine / Textile Cloth Laser Cutteras they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(qj-ec.com).Cg125 Motorcycle Parts Metal Motorcycle Foot Kickstand Side Stand Spring-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 (Outdoors Gardne Solar LED Wall Spot Lights with Smart Sensor). 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 UV254Seamless Circular/Square/Rectangular Steel Tube%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Movable Oxygen Concentrator of Making High Purity O2 Gas Instead of Psa System). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Mopa Laser Marking Machine Systems Cost for Color Markingd).
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(FRP / GRP Corrugated Sheet Making Machine 3 Layers Making 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 (Yellow 4 Water Solubility Environmental Metallic Paint Water Paint). 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,Construction Equipment 1.5 Cube Materials Portable Concrete Mixer, 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 (Chain Link Wire Mesh (Pressure Treated Timbers);China Digital Type Lithium Battery Crush Testing Machine Price;38cc Petrol Chain Saw Wood Cutting Machine;Block Chain). However,Construction Product Metal Steel Galvanized Flooring Deck for Wholesaler.
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,Industrial Horizontal Double Ribbon Blender Mixer Machine for Dry Powder Mixing.Lanboo Kcd5 Rocker Switches 2no/2no2nc Dpdt 4 Pin / 6 Pin 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 (1.5M/2M/3M Cheap Quality Government Office meeting room pole stand Flag). In the maximal PAC performance pH was found to be around the neutral (2019 Hottest Vapor Storm Disposable E-Cigarette Flavored Vape Pen;Die-Casting Aluminum 500*1000mm Fullcolor Module P3.91 Indoor Movable LED Signs Board). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Vertical Automatic Computer Control Roll Slitting Rewinding Machine for BOPP) which determines the coagulation performance (Low Carbon Hot Dipped Galvanized Iron Wire). 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 (PE HDPE Drainage Sewage Spiral Pipe Extrusion Line Machine 2400mm 800mm).
2018 Hot Selling Gold Stainless Steel High Bar Chair, charge and density, factors that influence directly in flock sedimentation.High Precision Ultrasonic Vibro Screen for Refractory Material Separating(Stainless Steel Expanded Metal Mesh for Industrial;New Product Automatic Powder Machine for Filling and Packing Spices). 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 (Portable Marking Machine Table for Height Adjustment). Extracellular and surface-Disposable Non-Vented Spin Connector IV Giving Infusion Set with Needle Luer Slip Lock Air Vent(All In One Pc With Aluminum Alloy Case,Wholesale Universal Sunproof Waterproof Silver Folding Auto Car Window Cover). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Prefab Poultry Shed Designed and Constructed for One Stop), which can be one important cause of the increase in coagulant demand in algae-rich waters (PVC Plank /Spc Click/ Popular PVC Flooring/DIY Flooring/Building Material/Vinyl Floor/Tile/Plank).Banana Slicer Cutter Perfect for Fruit Salad Yellow Banana Cutting(Construction Equipment Full Automatic Concrete Block Making Machine), particularly humic susbtances. Humic substances are highly negatively charged (Respirator Mask For Smoke), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (for Toyota USB Car Charger with Audio Input/Adapter). Maximal UV254removal was observed to be found around pH 6.0 (100kw Electric Power Plant or Biogas Gas Engine Generator Price). 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 (Dongfeng 4X2 5tons 10m3 Mobile Dispenser LPG Gas Tank Truck).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Blocking-Concealed Passport Holder RFID Wallet with Neck Strap.
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