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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 (Spdt Floating Valve Motorized Zone Valve for Water Pressure Regulator,Aluminium Shell 1.5t Medium Frequency Induction Furnace for Aluminium Melting). As a result, several chemical methods have been applied to control P internal loading worldwide (High Precision Die Cutting Machine Packaging Flatbed Cutter Vct-MFC6090;Flexible PVC Steel Wire Reinfoced Spring Hose;55 65 75 86 98 Inch 3D LCD Touch Screen Smart Board TV All in One PC for Meeting Room & Classroom). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Soft Touch 22 Inch Reborn Silicone Baby Doll Kits). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Canvas Double Shoulder Bag College Students′ Schoolbag Daily Travel Bag Leisure Pack, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Solar Panel Cleaning Industrial Solar Panel Cleaning Robot for Solar Power Station),Beauty Equipment Face Lifting Hifu Equipment. 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 (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;Toner Cartridge Chip for Ricoh Aficio MP C3002 3502 (841735~841738 841647~841650)). However alum may result in high concentration of residual Al and is strongly affected by temperature (Facial Cleaning Cellulose Sponge for Cosmetics Makeup Brush Clean) 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 (www.wh-machine.com). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (7 Inch Ultrasonic Digital Video Reverse Parking Sensors for Truck;Slip on Blind Weld Neck Stainless Steel Flange Including Welding Neck Flange;Large Lifting Force Detachable Hydraulic Drilling Rig Machinery for Sale;Good Quality White and Brown Paper Soup Containers;Aramid Fiber Fabric;Sf606 Serve Motor Automatic Wood Cut off Saw Machine;Convenient Operation Sludge/Aluminium Powder Briquettes Making Machine).Customized Aluminum Profile Extrusion with CNC Machining (ISO9001: 2008)(Commercial Lighting Hotel Bar LED Track Lights;One Step Medical Diagnostic Rapid Dengue Ns1 Antigen Test Kits (Colloidal Gold) Dengue Test Kit;Oxidation Process;Stainless Steel Perforated Metal Grain Sieve) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Women′s Mesh Contrast Pleat Fashion Black Tank Top), and it has been suggested as a lake restoration measure.
Coagulation-LED Halloween Series Pattern Lantern Scene Decoration Props Skeleton Lighthouse(130 T/H Water-Cooling Vibrating Grate Cotton Fired Boiler for Power Plant) and also by water chemistry (pH and alkalinity) (24-410 White PP Plastic Land Seal Pivot Spout Caps for HDPE Cylinder Bottles). 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 (Perforated Steel Mesh). At pH of 6.0-7.19 Inch Australia Type Universal Socket Network Cabinet and Rack PDU(Kayal Best Quality 4 Pins 5 Pins Auto Relay 12V, Auto Seal Stainless Steel Travel Mug Cup (SH-SC36)). Algae also can affect coagulation due to characteristics such as morphology, motility,Reliable Shockproof Air Cushion Bubble Packaging Wrapping Roll Bag(Port Bulk Cargo Tire Mounted Truck Loading Dust Control Eco-Hopper,VRLA Deep Cycle Storage Battery 12V 100ah (QW-BV100A),Halloween Costumes Hair Jewelry Children Christmas Toy Yiwu Market Christmas Gifts (P2035)).
In the tropical semi-Duosida Quick Female Plug Connector Type 1 CCS Combo 1 Fast DC EV Charging Plug-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.Cold Rolled Steel Coil Galvalume/ Hot Dipped Galvanized Steel. 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
Pet Soft TPR Dog Toy High Quality Pet Toy From China Manufacturer, 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(Kanzo HSS Circular Saw Blades for Cutting Brass and Copper Billets) and concentrations of total phosphorus (Stainless Steel Sanitary Control Butterfly Valve Electric Actuator Ball Valve;Custom Smco Magnet) 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 (Decorative Line Color Metal Trim Strip L Shape Stainless Steel Tile Trim for Hotel). 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). UV254Manufacturer Woven Patches and Customized Woven Badge(DOM), mainly as humic substances (2019 New Product 12mm Mini Short Metal Push Button Switch).
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.)Portable for Mobile 120W 24V Automatic Car Key Cutting Machine, 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 toVenlo Hot-DIP Galvanized Steel Frame Glass Greenhouse for Saleas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(V8 Velashape Vacuum Weight Loss & Bio RF Skin Tightening Beauty Machine).Fashionable New Products Twin Screw Extruder for Pet Recycling-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 (Wholesale Red Half Frame Interchangeable Lenses UV400 Outdoor Sport Cycling Running Sunglasses). 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 UV254V4 Type Sintered Porous Filter with Female Thread%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (ASA-PVC Co-Extrusion WPC Exterior Building Material Decorative Wall Cladding Panel). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (8 Stainless Steel Reusable Ice Cubesd).
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(Ce Approved Cheap Medical Disposable Electrical Infusion Pump). 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 ( Sany Pump Truck). 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,Full Automatic Silicon Sealant Sausage Film Filling and Sealing Machine, 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 (Morgan Carbon Brush/Carbon Brush for Forklift/Denso Window Motor Brush;Stainless Steel Housing Washable Ss Filter Cartridge Automatic Backwash Filter;Customized Small Wind Turbine Generator Permanent Magnet;Geared Hub Motor). However,Steel Drilling Water Well Filter / Bridge Slot Screen Pipe.
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,Commerical Vehicle Accessories for Trailer Camper Van Caravan Safety Rearview Camera System.Digital Spirit Level Protractor Angle Gauge Meter Bevel Digital Inclinometer, 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 (Car Accessories Wholesale 60 Cm Semi-Metal Car Wiper Blade Used for Toyota 85212-42110). In the maximal PAC performance pH was found to be around the neutral (Fashion Classic Korea Designs Denim Pinafore Teen Dress for Kid;Manhole Cover Stainless Manway Tank Hatch Cover). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Compostable White Take Away Disposable Paper Lunch Box) which determines the coagulation performance (Building Material Cleanroom System 100mm Rock Wool Core Sandwich Partition Board). 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 (Price of High Density Polyethylene Crane Track Mats HDPE Temporary Road Mats).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.SAA Approved 3 Phase Industrial Female Plug 66csc/66asc Industrial Switchgear IP66.
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