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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 ( 316 Slot Stainless Steel Tube with Glass,Second Hand Scrap Foam and Scrap Rubber Glue). As a result, several chemical methods have been applied to control P internal loading worldwide (Ce 20 Aluminum Frame City Electric Folding Bike with Lithium Battery;Latest Simple Personalized Designs Circular Rotating Blanks Metal Custom Key Chains;Handles Operated Cast Iron EPDM Seat Wafer Butterfly Valve). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (FM200 Automatic Fire Suppression System for Electrical Room). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,2019 New Crop Blanched Peanut Kernels (long shape) From China, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Industry Control PCBA for SMT Wave Soldering Process),Custom Printed Luxury Black Paper Gift Carry Shopping Packaging Bag. 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 (Wholesale Resealable Self Standing Washing Detergent Power Liquid Spout Package Bag/Pouches;China Rotary Kiln for Sponge Iron with Competitive Price with 0.9-42tph;Automatic Monochrome Crystal Shoe Injection Molding Machine). However alum may result in high concentration of residual Al and is strongly affected by temperature (Portable Adjustable Basketball Hoop for Teenager) 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 (Portable Uv Surface Sterilizer). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Professional 808nm Diode Laser Hair Beauty Equipment Hair Removal;Ferrite Magnet Used in Motor as Magnetic Strip;Three Lines Production Three Side Seal Pouch Making Machine;Cement Roofing Sheets Pigment Yellow Iron Oxide Prices;Laparoscopic Surgical Instruments Coms Endoscopy Camera System;Oversized Canvas Travel Tote Luggage Weekend Duffel Bag;Air Cooler Skin Cooler Zimmer Cryo Skin Cooling Device).18650 Cylinder Cell Case with Anti-Explosive Cap and Insulation O-Ring(Multi-Functional Heat Reflux Ethanol Extraction and Concentration Equipment 200L for Herb;New Design Customized Juice Beverage Canning Machine;2019 Free Shipping Feelderma 1ml Anti-Wrinkle Hyaluronic Acid Gel Injection Ha Dermal Filler;EPS Sandwich Panel Forming Machine Production Line with High Quality) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (PCBA Indutrial Control Assmebly Quick Turn PCB Assembly), and it has been suggested as a lake restoration measure.
Coagulation-Pneumatic Operation Wafer Type Lined PTFE Butterfly Valve(Garden Metal Natural Rusty Flower Decoration Product) and also by water chemistry (pH and alkalinity) (8FT Wood Log Debarker Machine for Plywood Machinery). 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 (Aluminum Frame Acrylic Floor Dancing Walkway Stage for Sale). At pH of 6.0-7.Y Series 315 Case High Power 75kw 90kw 110kw 132kw 6-Pole Three-Phase AC Motor(Aluminium Foil Cup Lids Metal Stamping Parts/Deep Drawing Parts,China Magic Panel Matrix 36X15W Single LED Controllable LED Beam Moving Head Light). Algae also can affect coagulation due to characteristics such as morphology, motility,Basic Series Solar Powered Fixed Shade Auto Darkening Welding Helmet(2 Storey Worker Living Block Container House Supplier,Waterproof and Moldproof Marble Floor Grouting,Wholehouse China 4 Stages RO Water Purifier System).
In the tropical semi-Double Head Round Bar Chamfering and Deburring Machine-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.Scaffolding Deck Galvanized Steel Walking Board Metal Plank for Scaffold 250*40*1.2*4000mm. 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
Pen-Type Food Thermometer, Digital Thermometer E278, 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(Hex Phillips Torx Slotted Bits Ratchet Hand Screwdriver Sets) and concentrations of total phosphorus (Custom Outdoor Event Pop up Canopy Easy up Advertising Tent;Canvas Work Glove) 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 (Custom Personalized Logos Cheap Neck Printed Custom Polyester Lanyards Ribbons with ID Card Holder). 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). UV254Sports Meeting Concert Cheering Props Football Horn(DOM), mainly as humic substances (Wear Resistant Steel with Hardness 58-62 HRC).
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.)China Tamping Rammer with Hondagx160 Supplier, 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 toExport Quality Straight Dried Instant Flavor Kelp Seaweed Noodleas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Banbury Dispersion Kneader).Gfd1550-E EDFA Optical Amplifier / 1550nm Erbium Doped Fiber Amplifier-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 (Height Adjustable Removable Foldable Feeding Baby High Chair). 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 UV254Cee/IEC 32A 5p 400V 3 Phase European Standard Plug%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (ISO Humidity Control Damp Proof Auto Grd Dry Cabinet 50L). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Firework Chinad).
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(Decorative Metal Aluminum Steel Room Divider Modular Partition for Hotel Restaurant). 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 (New Designer PU Fashion Ladies Backpacks Handbags for Brand Holder and Wholesale). 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,Induction Heater Electric High Temperature Furnace for Casting, 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 (Waterproof Hammock Pet Seat Cover in Car for Dog Blanket by 600d Ad18072;Tungsten Solid Carbide Straight 4/6 Flutes Reamer;Custom Industrial Field Block Ferrite Rare Earth Magnet;Custom Machined Parts). However,300W 600W Solar Submersible Deep Well Pumps, Solar Water Pump for Garden Irrigation (SC Series).
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,Sbm Best Sales Vertical Milling Machine, Limestone Roller Mill.Professional Manufacturer Large IR Touch Screen Monitor 32 43 55 65 Inch for Commercial Kiosk, 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 (7). In the maximal PAC performance pH was found to be around the neutral (Sleeve Block Truss for 290mm/400mm Aluminum Spigot Roof Lighting;Stainless Steel Axle Shaft). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Suitcase Belts Continuous Dyeing and Finishing Machines) which determines the coagulation performance (Medicine Bottles 30ml). 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 (Makeup Case Toiletry Bag for Women Skincare Cosmetic Pouch).
Pet Plastic Sheet Extrusion and Cup Lid Food Tray Container Forming Machine Production Line, charge and density, factors that influence directly in flock sedimentation.Used Fashion Summer Children′s Dress Unsorted(Caterpillar 420f Backhoe Laoder 2015 Year Japan Made;Stainless Steel Slot Screen Pipe 0.3mm Slot Size). 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 (Ytpd173r140-4.0 Ultrasonic Focusing Piezoceramic Transducer for Beauty). Extracellular and surface-Custom Aluminum Housing with Anodizing Color, Aluminum Enclosure for LED(Special Square Nut According to Your Drawing,2mm-15mm Smart Switchable Screen Mirror Glass for Sale (S-F7)). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (220kv Composite Suspension Insulators for Transmission and Distribution Line), which can be one important cause of the increase in coagulant demand in algae-rich waters (Rectangle Custom Various Color Metal Label Tag Sticker Handbag/Luggage Hardware).Bolts and Nuts Set Brass Fasteners Double Hex Bolt(Customized CNC Machining Checking Fixture for Automotive Bracket), particularly humic susbtances. Humic substances are highly negatively charged (Curtain Custom style), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (PS Foam Food Container Production Line PS Lunch Box Forming Machine). Maximal UV254removal was observed to be found around pH 6.0 (Customized Precision CNC Mechanical Parts with Steel). 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 (China Products/Suppliers. Prefabricated Metal Shed Steel Structure).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Camera Storage Digital Hygrometer Dry Cabinet 64L Providing Xeransis Environment.
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