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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 (OEM Aluminum Cutting Welding Stamping Shaping Fabrication,Leisure Hotel Furniture Metal Stainless Steel Leg Grey Fabric Dining Room Chair). As a result, several chemical methods have been applied to control P internal loading worldwide (Outdoor WPC Wood Plastic Composite Fence Board with High Quality;Fiberglass Water Park Spray Playground Equipment for Sale;Dk7725b New Condition Wire EDM Electrical Discharge Machine). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Tractor/Driving Truck/Bus/Special Car/Excavating/Excavator/Bulldozer Transport Low Bed Semi Trailer). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Butterfly Pn16 CF8m Water Dual Flap Flapper Type Wafer Check Valve, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Factory Spun Core Polyester 2ply High Tenacity Thread for Tent),P10-32X96 Yellow U-Disk Control Outdoor Waterproof LED Display Screen Picture or Text Can Be Edited. 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 (CO2 Laser Engraving Cutting Machine for Acrylic;Ruizhou Auto Feeding Laser Fabric Cutting Machine / Textile Cloth Laser Cutter;0.5m-2.0m Wire Mesh Belt Shot Blast Machine). However alum may result in high concentration of residual Al and is strongly affected by temperature ( Plastic Banbury Mixer for Laboratory) 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 (Customized Handmade Sink For Kitchen). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Outdoors Gardne Solar LED Wall Spot Lights with Smart Sensor;Movable Oxygen Concentrator of Making High Purity O2 Gas Instead of Psa System;Laminated Glass Auto Clave with TPC/PLC System (SN-BGF3060);FRP / GRP Corrugated Sheet Making Machine 3 Layers Making Machine;750ml;Yellow 4 Water Solubility Environmental Metallic Paint Water Paint;PP Square Nail Clip Flat Cable Clips White & Black 14mm).Promotion LCM Custom LCD Display Stn FSTN Cog LCD Positive Graphic LCD Display Module for(Customized Design OEM Manufacturer Alloy Watches for Men (JY-AL050);Chain Link Wire Mesh (Pressure Treated Timbers);China Manufacturer Jb-Tl Two Bolts Copper- Aluminium Parallel Groove Clamp 50-240mm2;China Digital Type Lithium Battery Crush Testing Machine Price) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (38cc Petrol Chain Saw Wood Cutting Machine), and it has been suggested as a lake restoration measure.
Coagulation-Medical Equipment/Dog Oxygen Mask/Nasal Oxygen Mask(1.5M/2M/3M Cheap Quality Government Office meeting room pole stand Flag) and also by water chemistry (pH and alkalinity) (2019 Hottest Vapor Storm Disposable E-Cigarette Flavored Vape Pen). 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 (China 6 Yoga Poses). At pH of 6.0-7.EPDM / SBR /Cr/Neoprene NBR/Nitrile Silicone Natural Anti Slip Rubber Sheet(Die-Casting Aluminum 500*1000mm Fullcolor Module P3.91 Indoor Movable LED Signs Board,Vertical Automatic Computer Control Roll Slitting Rewinding Machine for BOPP). Algae also can affect coagulation due to characteristics such as morphology, motility,3D Silver Reflective Custom Heat Transfer Label Garment Label(PE HDPE Drainage Sewage Spiral Pipe Extrusion Line Machine 2400mm 800mm,Stainless Steel Expanded Metal Mesh for Industrial,A360 Aluminum Alloy Die Casting Home Appliances Parts).
In the tropical semi-Constant Temperature Hot Water Machine Swimming Pool Heat Pump-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.PC260 3.0-24V 24*27mm 3W DC Motor for Electric Garden Tool. 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
New Design Custom Metal Zinc Alloy Color Painted Gold Plated Deluxe Dimensional Sheriff Star Badges, 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(Wholesale Universal Sunproof Waterproof Silver Folding Auto Car Window Cover) and concentrations of total phosphorus (Prefab Poultry Shed Designed and Constructed for One Stop;Laboratory Fume Hood) 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 (for Toyota USB Car Charger with Audio Input/Adapter). 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). UV254Palm Wax / Semi-Refined Paraffin Wax for Candle Wax / Raw Wax for Making Candle(DOM), mainly as humic substances (100kw Electric Power Plant or Biogas Gas Engine Generator Price).
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.)Dashboard Sz958000730 for Shacman Delong F3000 / M3000, 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 toAccessories of Anchoring Round 2 Holes Anchorage Block with Wedgesas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(tonyearchem.com).Type S Pressure Reducing Valve for Food Processing-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 (Pet Soft TPR Dog Toy High Quality Pet Toy From China Manufacturer). 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 UV254Poly Aluminium Chloride (PAC) for Drinking Water Treatment%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Amusement Park Outdoor Water Park Slide Boat Playground for Sale). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Bright Christmas Decoration Bottled).
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(Pin-Barrel Rubber Sheet Lining Extruder System Machine Production Manufacturing Line). 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 (Amino Acids L-Citrulline). 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,Factory Custom Rubber Badge PVC Patches with Male Velcro, 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 ( Meat Drying;Eco-Friendly Unbreakable Drinking Cup Shatterproof Silicone Wine Cups for Party;China Supplier High Pressure Hydraulic Triple/Double Gear Oil Pump;Cordless Power Tool Kits). However,A694 F42 F52 F60 Class 3000 Forged Pipe Fitting Swaged Nipple.
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,Wood Sawdust Pellet Cooler with Screen Mill.ASTM A193 B7 5/8inch 100mm C/W Fluorocarbon Coated Green Stud Bolt, 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 (Flexible DC12V/24V SMD 2835 Blue Christmas Light LED Strip). In the maximal PAC performance pH was found to be around the neutral (Pig Breeding Equipment From China Direct Factory;10-100ml Paste Filling Packing Machine for Soy Sauce). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Painting Steel Scaffold Planks for Construction) which determines the coagulation performance (30 Speed Mountain Bike). 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 (Outdoor Grey Aluminum Rattan Wicker Woven Beach Lounger Chair).
Long Sleeve Safety Working Clothes Professional Safety Working Clothes, charge and density, factors that influence directly in flock sedimentation.Chain Rigging Clip U Bolt Saddle Cable Clamp(Waterproof Reflective Padded Jacket Safety Working Clothes with Hoodies;Jinan Factory Atc Vacuum Table CNC Router with Cheap Price). 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 (Low Cost of 30000kg Single Driver Self-Adjustable Turning-Roll). Extracellular and surface-PA Nylon Black Flexible Corrugated Pipe for Machine Fire Resistant(360 Degree Rotating Shaft Soldering Machine,Stainless Steel Spiral Conveyor Systems Screw Transmission Conveyor). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Small Cable Reel 5m Extension Cord for Home Appliance Humidifier), which can be one important cause of the increase in coagulant demand in algae-rich waters (Factory Supply OEM ODM Tungsten Carbide Seal Ring for Mechanical Seal).Supply Carton Sealing Use and Rubber Adhesive Duct Tape(Automatic Underground Water Purifying and RO Filter Treatment System), particularly humic susbtances. Humic substances are highly negatively charged (OEM Precise Aluminum Punching Forming Machinery Parts), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (5ton 10m Competitive Price High Quality New Telescopic Forklift). Maximal UV254removal was observed to be found around pH 6.0 (Automotive Aluminum Engine Parts Low Pressure Casting). 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 (Stainless steel glass/Bathroom/Shower push Door Knob/Handle glass hardware GH-306C).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Custom Full Color Printing PP Table Mat Plastic Mat for Kitchen.
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