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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 (Top Quality Vehicle GPS Tracker with Fuel Cap Sensor M508,Sun Energy Heater). As a result, several chemical methods have been applied to control P internal loading worldwide (430 Black Mirror Decorative Stainless Steel Sheet in Foshan; Door;Square Shape Glass Perfume Bottle Refillable Glass Perfume Bottle Atomizer Mist Bottle). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Atex Approved Level Measuring Instrument Level Sensor). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Luxury Fashion Lady Women Shoulder Tote Bag Leather Evening Handbag, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (201/304/316L/321/310 Stainless Steel Large Diameter Pipe&Tube),600L Stainless Steel Beer Fermentation Tank 3-Vessels Brewhouse. 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 ( LPG Hose Best Choice for Home Use;High Performance Electroplated Diamond Wire/Steel Wire/Diamond Wire;Wholesale Foldable Desk Silicon Mobile Phone Stand). However alum may result in high concentration of residual Al and is strongly affected by temperature (10 Axis 3D CNC Heavy-Duty Metal Wire Bending Forming Machine) 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 (U Bolt M12). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Bright Solar Power Outdoor LED Light Motion Activated Light for Garden Patio Path Pool; Table Gas Stove;API-5CT Standard Seamless Steel Pup Joint /Oilfield Services;Custom Lf 125kHz/Hf 13.56MHz Pet/PVC RFID Contactless Smart Card with Cheap Price;FKM;Supporting DDR4 RAM Intel Core I5 Mini PC Computer;Vodafast A2 Stainless Steel Channel Nuts with Long Spring).Wholesale Baby Shoes Kids Boy Wear LED Flashing(Double Glazing Equipment Automatic Desiccant Filling Machine Insulating Glass Machine;Custom Aluminum Stainless Steel 90 Degree Angle Brackets;Methane Gas Detector;5kw 12V/24V/48V/DC to AC/110V/120V/220V/230V/240V Pure Sine Wave Solar Power Inverter) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Aluminum/Cooper/Galvanized Tube Precision Pipe Making Machine), and it has been suggested as a lake restoration measure.
Coagulation-Stainless Steel 304 316 Railing Fittings Casting Round Tube Plate(4mm Sheet Metal Bending Machine 100ton Plate Bending Machine with Da52s) and also by water chemistry (pH and alkalinity) (OEM Aluminum Cutting Welding Stamping Shaping Fabrication). 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 (UL FM Dn50 Grooved Control Signal Handles Butterfly Valve). At pH of 6.0-7.Non-Smoke E7018 E6018 Welding Rod Carbon Steel Welding Electrodes(Outdoor WPC Wood Plastic Composite Fence Board with High Quality,Fiberglass Water Park Spray Playground Equipment for Sale). Algae also can affect coagulation due to characteristics such as morphology, motility,Factory Direct Seal Y14f General Power Relay 5 Pins(Dk7725b New Condition Wire EDM Electrical Discharge Machine,Tractor/Driving Truck/Bus/Special Car/Excavating/Excavator/Bulldozer Transport Low Bed Semi Trailer,Air Solenoid).
In the tropical semi-30L 600W Dental / Lab Ultrasonic Cleaner Washer Ultrasound Cleaning Machines-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.G95 LED Filament Bulb Light Lamp 8W 110-130V/220-240V Edison Bulb with Ce RoHS. 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
Lockey Loto Durable Standard Safety Gate Valve Lockout with Ce, 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(0.5m-2.0m Wire Mesh Belt Shot Blast Machine) and concentrations of total phosphorus ( Plastic Banbury Mixer for Laboratory;Hot Sale 3/4 Brass Reusable Hose Pipe Fitting for Garden) 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 (Laminated Glass Auto Clave with TPC/PLC System (SN-BGF3060)). 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). UV254FRP Fiberglass Underground Septic Tank for Effluent Treatment(DOM), mainly as humic substances (FRP / GRP Corrugated Sheet Making Machine 3 Layers Making Machine).
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.)Pgz1000 Crystal Industry Pneumatic Scraper Bottom Discharge Flat Basket Filter Centrifugal Separator, 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 toChain Link Wire Mesh (Pressure Treated Timbers)as they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Silver 925 K Gold Double Line Fashion Necklace Jewelry).Inflatable Floating Water Playground Water Island for Commercial Business Usage-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 (1.5M/2M/3M Cheap Quality Government Office meeting room pole stand Flag). 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 UV254Solid Carbide Straight Slot Reamer with Inner Cooling Hole%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (2019 Hottest Vapor Storm Disposable E-Cigarette Flavored Vape Pen). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Braiding Machine For Roped).
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(Vertical Automatic Computer Control Roll Slitting Rewinding Machine for BOPP). 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 (PE HDPE Drainage Sewage Spiral Pipe Extrusion Line Machine 2400mm 800mm). 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,Balaclava Hood Ski Bike Cycling Face Mask Cap Fleeces Helmet, 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 (Portable Marking Machine Table for Height Adjustment;Wholesale Universal Sunproof Waterproof Silver Folding Auto Car Window Cover;Prefab Poultry Shed Designed and Constructed for One Stop;pv electrical power wire). However,Commercial Promotion White Inflatable Party Tent for Exhibition.
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,Camping Gas Stove, Outdoor Stove, Table Gas Stove.Toroidal Power Transformer for Household Audio, 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 (PVC Plank /Spc Click/ Popular PVC Flooring/DIY Flooring/Building Material/Vinyl Floor/Tile/Plank). In the maximal PAC performance pH was found to be around the neutral (Construction Equipment Full Automatic Concrete Block Making Machine;for Toyota USB Car Charger with Audio Input/Adapter). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (100kw Electric Power Plant or Biogas Gas Engine Generator Price) which determines the coagulation performance (Cell Mirror). 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 (Dongfeng 4X2 5tons 10m3 Mobile Dispenser LPG Gas Tank Truck).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Counter Top Chips Worker Infrared Chips Warmer.
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