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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 (Wood Acrylic Ss CO2 Tube CNC Laser Cutting Machine for Metal and Nonmetal,Aluminium Window Frame Making Machine). As a result, several chemical methods have been applied to control P internal loading worldwide (SKF NTN Chik Koyo Deep Groove Ball Bearings 6308 Zz Ball Bearing Turbo for Sale 40*90*23mm;Upal Cheap Folding Steel Gazebo Tent with PVC Fabric Roof;5r 200W LED Moving Head Beam 3 in 1 Stage Lighting). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (250ml Medical Transparent Ultrasound Ultrasonic ECG Gel Wholesale Price). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Window & Vinyl Sticker, Car Sticker, Label, Sticker, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (New Volakas White Marble),Invt Bd 3000W/5000W Hybrid Solar Power Inverter for Solar Power System Home. 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 (Top Supplier Lcoe Cost Down 1500V Dual Glass 320W 330W 340W Poly Solar Panel;Hybrid Power System 150kw Electricity Generating System with Battery Bank;Customzied SKD11 Shear Blades for Leather and Plastic). However alum may result in high concentration of residual Al and is strongly affected by temperature ( Keyboards) 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 (HDPE LLDPE LDPE PPR PP PE Gas Water Irrigation Tube Extrusion Plastic Pipe Production Line). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (10kv Xple Heat Ahrinkable 1-Core Outdoor Termination Kit (Section 500~630 mm^2);Aluminum/SS304 Material Bathroom Mirror and Satin Shower Glass Sliding Door Handle;Sermorelin Powder Anabolic Raw Powder for Human Grow Hormone;Beautiful Lvt Eco-Indoor Wood Grain Click Planks Vinyl WPC Flooring;Super Professional Mrl Passenger Elevator Observation Home Lift;Ae Bifacial Solar PV Panel 270W Poly German Quality;Long Rod Electrical Suspension High Voltage Polymer Insulator).Acrylic Diamond Polishing Machinery & Plastic Edge Finishing Trimming Machinery(Chemical Vacuum Coating Single Stage Rotary Piston Pumps;Original Germany Bitzer Brand Compressor 4hc-1.2y;Crok Shape Led String Lights;Custom Black-White Printed Product Operation Instruction) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Spdt Floating Valve Motorized Zone Valve for Water Pressure Regulator), and it has been suggested as a lake restoration measure.
Coagulation-Ce Certification Jigging Machine for Manganese Ore Extraction/Manganese Ore Refining Machine(High Precision Die Cutting Machine Packaging Flatbed Cutter Vct-MFC6090) and also by water chemistry (pH and alkalinity) (Flexible PVC Steel Wire Reinfoced Spring Hose). 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 Manufacturer Stone Diamond Grinding Cup Wheel for Floor Grinding). At pH of 6.0-7.China Aluminum Anodizing Anodized CNC Turning Machining Parts(55 65 75 86 98 Inch 3D LCD Touch Screen Smart Board TV All in One PC for Meeting Room & Classroom,Soft Touch 22 Inch Reborn Silicone Baby Doll Kits). Algae also can affect coagulation due to characteristics such as morphology, motility,2 Head Embroidery Machine Cap Flat T Shirt Embroidery(New Design Silicon Watch Band Strap for Apple Watch Series 4 Mesh Shape Sport Band for Apple Watch,PU Imitation Clothing Leather Garments Material -Freman,Usb C Hub For External Hard Drives).
In the tropical semi-High Quality Plastic Bulk Dry Food Dispenser Single Cereal Candy Dispenser for Sale-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.Ex-Proof Motorized Flange End Ball Valve (PQ9B41F-300Lb). 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
Heavy Duty High Chrome Sand Dredger Mining Tailing Slurry Pumping Machine for Chrome Mining, 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(7 Inch Ultrasonic Digital Video Reverse Parking Sensors for Truck) and concentrations of total phosphorus (Slip on Blind Weld Neck Stainless Steel Flange Including Welding Neck Flange;30oz Stainless Steel Insulated Tumbler) 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 (Sf606 Serve Motor Automatic Wood Cut off Saw Machine). 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). UV2541.2mm/1.6mm Stainless Steel SS 304 Wire for Thermal Spray Wire(DOM), mainly as humic substances (Convenient Operation Sludge/Aluminium Powder Briquettes 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.)High Quality Industrial Grade Anhydrous Sodium Sulfate, 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 toWomen′s Mesh Contrast Pleat Fashion Black Tank Topas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Fire Rated Decorative Internal HPL Laminated MGO Wall Board).LSR Injection Mold Tooling for Medical Nipple-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 (Kayal Best Quality 4 Pins 5 Pins Auto Relay 12V). 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 UV254Wholesale Promotional Children Painting Apron, Child Apron, Kids Apron, Disposable Nonwoven Apron%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir ( Auto Seal Stainless Steel Travel Mug Cup (SH-SC36)). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (HDPE Abalone Leisure Fishing Aquaculture Floating Circular Square Deep Sea Net Caged).
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(VRLA Deep Cycle Storage Battery 12V 100ah (QW-BV100A)). 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 (Customized Lift Gas Support Spring with Metal Eyelet End Fitting). 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,100% Water Soluble AAA45-P-HCl Animal Source Amino Acid Fertilizer, 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 (Stainless Steel Sanitary Control Butterfly Valve Electric Actuator Ball Valve;30g 50g Plastic PP Empty White Cosmetic Cream Jar;Fiberglass Grating;Quality Powder Coating Machinery for Lawn Mower). However,2019 New Factory Direct Metal Bird Feeder for Garden Decoration.
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,Manufacturers Wholesale Microfiber Car Cleaning Towel.Gdg24 0.55kw 550W 0.75HP 24L Oil Free Air Compressor, 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 (Decorative Line Color Metal Trim Strip L Shape Stainless Steel Tile Trim for Hotel). In the maximal PAC performance pH was found to be around the neutral (2019 New Product 12mm Mini Short Metal Push Button Switch;Black Blue Red Brown Green Gray Color 3 Tab Asphalt Shingle for Sell). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Dental Alloy Cobalt Chromium porcelain Fused to Metal) which determines the coagulation performance (Unique Design Ambulance Emergency First Aid Kit). 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 (Dongguan Factory 2019 High Quality PP Luggage Trolley Set for Air Travel).
Tempered/Toughened Glass/Window/Shower Door Float Glass (T-TP), charge and density, factors that influence directly in flock sedimentation.3-Axle 30mt LPG Haulage Truck Trailer Depot Gas Transportation Tanker(Venlo Hot-DIP Galvanized Steel Frame Glass Greenhouse for Sale;Higher Quality Easy Installation Luxury Vinyl Tile Spc Flooring Plank). 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 (Roll Forged Steel Sheaves for Crane Sheave Block). Extracellular and surface-Best Factory Price Metallic Honor Medal with Neck Ribbon(China Golf Indicator,Wholesale Red Half Frame Interchangeable Lenses UV400 Outdoor Sport Cycling Running Sunglasses). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (ASA-PVC Co-Extrusion WPC Exterior Building Material Decorative Wall Cladding Panel), which can be one important cause of the increase in coagulant demand in algae-rich waters (Shacman F3000 6X4 6000 Gallon Oil Tanker 20000liters Fuel Tank Truck).Filter Press Machine for Sand Washer Sludge Dewatering Working Site in China(Ce Approved Cheap Medical Disposable Electrical Infusion Pump), particularly humic susbtances. Humic substances are highly negatively charged (Featured), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles ( Sany Pump Truck). Maximal UV254removal was observed to be found around pH 6.0 (Textile Dispersant Naphthalene Sulphonate Superplasticizer). 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 (2.7 Inch 16X2 Character 1602 LCD Display COB LCD Module 16*02 16*2 LCD 2.7′′).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Custom Product Rapid Prototype Making/Vacuum Casting/CNC Machining Rapid Prototype.
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