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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 (Square Shape Glass Perfume Bottle Refillable Glass Perfume Bottle Atomizer Mist Bottle,Plastic Sheet Roofing). As a result, several chemical methods have been applied to control P internal loading worldwide (Atex Approved Level Measuring Instrument Level Sensor; LPG Hose Best Choice for Home Use;High Performance Electroplated Diamond Wire/Steel Wire/Diamond Wire). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Wholesale Foldable Desk Silicon Mobile Phone Stand). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,White/Gray Colors U-PVC Water Supply Pipe for Plumbing System, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (T5 T8 T10 Led Tube Lighting),Microfiber Towel Quick Dry Towel Set for Beach, Travel, Swim, Pool, Camping, Outdoors and Sports. 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 (10 Axis 3D CNC Heavy-Duty Metal Wire Bending Forming Machine;Bright Solar Power Outdoor LED Light Motion Activated Light for Garden Patio Path Pool; Table Gas Stove). However alum may result in high concentration of residual Al and is strongly affected by temperature (API-5CT Standard Seamless Steel Pup Joint /Oilfield Services) 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 (W01). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (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;Double Glazing Equipment Automatic Desiccant Filling Machine Insulating Glass Machine;China Tractor Hydraulic Cylinders;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).Seamless Steel Rolled Ring, Forged Steel Rings for Large Diameter, Manufacturer of Slewing Ring(Aluminum/Cooper/Galvanized Tube Precision Pipe Making Machine;4mm Sheet Metal Bending Machine 100ton Plate Bending Machine with Da52s;Foldable Magnetic Closure Paper Packaging Boxes;OEM Aluminum Cutting Welding Stamping Shaping Fabrication) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Outdoor WPC Wood Plastic Composite Fence Board with High Quality), and it has been suggested as a lake restoration measure.
Coagulation-Inconel 625 2.4856 Polished Nickel Alloy Tube/Nickel Alloy Pipe(Fiberglass Water Park Spray Playground Equipment for Sale) and also by water chemistry (pH and alkalinity) (Dk7725b New Condition Wire EDM Electrical Discharge 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 (m.szfanshitong.com). At pH of 6.0-7.Porcelain Tea Cup and Saucer Sets Wholesale Tableware Ceramic(Tractor/Driving Truck/Bus/Special Car/Excavating/Excavator/Bulldozer Transport Low Bed Semi Trailer,CO2 Laser Engraving Cutting Machine for Acrylic). Algae also can affect coagulation due to characteristics such as morphology, motility,Customized Disposable BBQ Bamboo Round Stick and Skewers.(Ruizhou Auto Feeding Laser Fabric Cutting Machine / Textile Cloth Laser Cutter,0.5m-2.0m Wire Mesh Belt Shot Blast Machine,Actuator Butterfly Valve).
In the tropical semi-Ceramic Coil 0.5ml Cartridges Disposable Cbd Vape Pen-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.Sesame Almond Cashew Nut Peanut Butter Making Processing Machine. 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
Big Engine, Large Output Forestry Application Biomass Wood Chipper, 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(Movable Oxygen Concentrator of Making High Purity O2 Gas Instead of Psa System) and concentrations of total phosphorus (Laminated Glass Auto Clave with TPC/PLC System (SN-BGF3060);China Famous High Quality Carbon Filter & Apparatus) 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 (PP Square Nail Clip Flat Cable Clips White & Black 14mm). 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). UV254LED Lighted Mirror with Bluetooth Functions(DOM), mainly as humic substances (Customized Design OEM Manufacturer Alloy Watches for Men (JY-AL050)).
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.)Br42 Red Color Mushroom Head Push Button Switches, 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 to1.5M/2M/3M Cheap Quality Government Office meeting room pole stand Flagas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Mica Tape).Port Bulk Cargo Tire Mounted Truck Loading Dust Control Eco-Hopper-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 (Vertical Automatic Computer Control Roll Slitting Rewinding Machine for BOPP). 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 UV2542017 New Material Fashion Luggage Good Suitcase%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (PE HDPE Drainage Sewage Spiral Pipe Extrusion Line Machine 2400mm 800mm). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (2019 Custom Fashion Sun Glasses UV400 Promotional Plastic Cheap Sunglassesd).
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(New Product Automatic Powder Machine for Filling and Packing Spices). 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 (Portable Marking Machine Table for Height Adjustment). 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,Stainless Steel SS304 and SS316 Closed Body Turnbuckle, 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 (PVC Plank /Spc Click/ Popular PVC Flooring/DIY Flooring/Building Material/Vinyl Floor/Tile/Plank;Construction Equipment Full Automatic Concrete Block Making Machine;for Toyota USB Car Charger with Audio Input/Adapter;Electronic Products Plastic Housing supplier). However,Electric Hand Circular Saw for Wood Cutting 185mm.
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,Made in Malaysia Small Panasonic R134A Refrigeration Compressor (QB66).Alternator for Toyota 91, 92 Mr2, 100211-6110, 27060-74180, 2706074180, 1002116110, 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 (100kw Electric Power Plant or Biogas Gas Engine Generator Price). In the maximal PAC performance pH was found to be around the neutral (Dongfeng 4X2 5tons 10m3 Mobile Dispenser LPG Gas Tank Truck;Centrifugal Casting Tin Bronze Bushing with Machining). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Bolts and Nuts Set Brass Fasteners Double Hex Bolt) which determines the coagulation performance (Air Source Heat Pump System). 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 (Accessories of Anchoring Round 2 Holes Anchorage Block with Wedges).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.L Shape Outdoor Sofa Set with Cushion and Coffee Table (DW-SF1906).
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