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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 (Full Automatic Silicon Sealant Sausage Film Filling and Sealing Machine,Fully Automatic Industrial Microwave Dehydrator). As a result, several chemical methods have been applied to control P internal loading worldwide (Filter Press Machine for Sand Washer Sludge Dewatering Working Site in China;Healong Fashion Sportswear Latest Design Blank Gym Sweatshirts Custom Cotton Hoody Sweatshirts;Padded and Comfortable Cushion Stainless Steel Carmeno Velvet Dining Chair). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (3G/H Ozone Generator for Air Purification and Sterilization). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Vci PE Film for Ferrous Metal with Anti-Rust Performance, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (China Graphite Milling Cutter),Solar Garden Peacock Stake with Solar Light for outdoor Decoration. 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 (Greenpedel X1 Foldable Electric Scooter with Seat for Adults;Reinforced Aluminum Foil Pipe Joint Electric Tape Manufacturer in China;Basketball Rebounded Practice Machine for Professional Trainer (S6839)). However alum may result in high concentration of residual Al and is strongly affected by temperature (Aqualand 8feet Inflatable Rubber Fishing Boat/Rowing Dinghy/Motor Boat (aql250)) 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 (2019 New Alloy Crystal Bracelet/Custom Crystal Bracelet/Promotional Bracelet). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Transmission Parts Linear Ball Bearing with Shaft for Setting Machine;Pretty Precisely Automatic PV Strut Roll Formin Machine with High Quality;Classic European Style Universal Wrench& General Reciprocal& Utility Wrench;Hot Sale High Density Hotel Cashmere Wool Polyester Blanket;36pin Mdr Scsi Connector;220V UFO Shaped LED Bulb E27 Efficiently Energy Saving LED Light;Mini Building up Block Pen Highlighter Marker Pen Writing Drawing Stationery).Carrier Roller for Sany Hydraulic Excavator Sy16-Sy850h-8(Cg125 Motorcycle Parts Metal Motorcycle Foot Kickstand Side Stand Spring;Blind Indicators Stud/Strips Stainless Steel Tactile;Mini Shopper Lady PU Leather Stitching Shoulder Bag for Fashion Handbag Women Bag;Fenugreek Extract Enhance Men′s Sexual Function) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Peaceful Animals Theme Inflatable Dry Slide for Zoos (CHSL640)), and it has been suggested as a lake restoration measure.
Coagulation-4.3 IPS Display 1080P Dash Cam 12 Mega Pixel Rear View Mirror with Parking Monitor, G-Sensor(Embroidery Sequins Lace Mesh Lace Fabric Embroidery Sequins Lace Mesh Lace Fabric) and also by water chemistry (pH and alkalinity) (NF3). 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 (Colorful Popular Barrier Fence Plastic Mesh Net). At pH of 6.0-7.China Top Supplier 2- (4-Chlorophenoxy) -2-Methylpropionic Acid with Best Price CAS: 882-09-7 C10h11clo3(Optical Solar Smoke Detector with Testing Button (ES-T601),Wkj-01/Mechanical Thermostat/ Room Thermostat/HVAC Controls). Algae also can affect coagulation due to characteristics such as morphology, motility,Transparent Single Crystal Alumina Sapphire Jewel Bearing and Components(1.5 Inch High Pressure Petrol/Gasoline Water Pump,15kw 19kVA 50Hz Home Standby Weichai Soundproof Diesel Generator,Net Extruder).
In the tropical semi-Handle Operation Flanged Lined PFA Butterfly Valve (D41F46)-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.Plastic Filter/Plastic Mbbr Filter Media for Water Treatment/ Electric Kettle Filtration. 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
High Quality Portable Deep Well Solar Pump Solar Water System, 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(Tecjet Cloth Printer Printing Machine 6090 DTG Printer) and concentrations of total phosphorus (Home Kitchen Appliance Digital Ozone Generator for Air Water Purifier;jinbinvalve) 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 (Automotive Electropainting). 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). UV254New Design Comfortable PU Cemented Men and Boy Sandal(DOM), mainly as humic substances (Aluminium Radiator Core for Profile or Alloy LED Lighting Other).
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.)Quality Assured Large Freight Volume Fire Resistant Rubber Conveyor Belt, 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 toPVC Cross Joint Pipe Fittings Equal Pipe Crossas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Square Thin SMD2835 12W LED Panel Light for Corridor).6 Panel Embroidered Fashion Fitted Cap Custom-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 (PCB Mounting Shielded Modular Jack Ethernet RJ45 Connector). 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 UV2543/2 Way 3h210 Airtac Hand Control Manual Pneumatic Air Valves%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir ( Fabric). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Face Serumd).
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(Fertilizing Machine Farm Tractor Mounted CDR-1000 Fertilizer Spreader). 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 (Vending Machine 12.1 Inch Embedded or Open Frame Capacitive Touch Screen Monitor). 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,Metalized Pink Color 3ml 5ml 10ml Perfume Roll on Container Bottle with Gold Aluminum Cap, 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 (Taiwan Spindle Vmc 850 3/4 Axis CNC Center Mini Small Vertical CNC Milling Machine 10000rpm Belt;Laboratory 2 Roll Mixing Mills Rubber Open Mixer Machine Factory;Professional Neck Jacquard Woven Lanyard Strap;New Arrival Korean Fish Crips Mobile Canteen Van). However,Popular Lifejacket EPE Foam Life Vest for Water Safety Equipment.
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,OEM Aluminum Housing Fuel Filter Housing for Truck/Train Parts.Rare Earth Metal Material Cerium Target for Magnetron Sputtering System, 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 (Foton/Forland 4X2 Mobile Snack/BBQ/Coffee/Hot Food Truck). In the maximal PAC performance pH was found to be around the neutral ( Pullover Fleece Tie Dye Hoody;Customized Machine Dustproof Bellow Cover for The CNC Guide). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Stainless Steel Pneumatic Three Way Non-Retention Sanitary Ball Valve) which determines the coagulation performance (Party Game Factory & Manufacturer). 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 (Stainless Steel for Indoor Wall Construction Materials).
Hot Sale High Grade Popular Jacquard Curtain Fabric for Living Room/Bedroom, charge and density, factors that influence directly in flock sedimentation.Custom Diecasting Fashion Zinc Alloy Enamel Metal Name Tag(Photo Album Self Adhesive PVC Foam Sheets for Inner Pages;ISO14001 & Ce Commercial Gym Adjustable Decline Bench 5037). 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 (Good Quality CNC Contour Sponge Foam Profile Vertical Cutting Machine). Extracellular and surface-Semi-Automatic LCD IC PCB Cof Soldering Machine(Artificial Grass Products Supplier,Single Prong Metal Chrome Pegboard Bracket Merchandising Display Hook). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Glass Meal Prep Containers Food Storage to Go for Home Kitchen Keep Food Fresh with Airtight Seal), which can be one important cause of the increase in coagulant demand in algae-rich waters (Gear Box Forged Steel Bw Ends Full Welded Ball Valve).Socket Weld Stainless Steel Flange Ss 150#, Pipe Flanges Schedule 40(Organic Waste Gas Treatment Device Gas Disposal on Hot Sale), particularly humic susbtances. Humic substances are highly negatively charged (Stainless Steel Machinery Parts Machining by Precision Casting), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Floor Glass Fiber Sandwich Honeycomb Panel for Truck Body Door Shower Room). Maximal UV254removal was observed to be found around pH 6.0 (OEM Trailer Parts Drop Axle Forging Spindle). 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 (10ml Portable Spray Perfume Glass Empty Bottle Atomizer).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Household Home Textile Cleaning Cloth Warp Knitted Absorbency Cheap Kitchen Wash Clean.
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