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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 (Medical Equipment One Step Tp Device Syphilis Rapid Test Kit,Custom Sized Vegetable Capsules). As a result, several chemical methods have been applied to control P internal loading worldwide (Agricultural Machinery Partslinear Bearings Kh3050; 12V- 48V DC;Wholesale Bedding Set Hotel 100% Cotton Bed Sheets White). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Factory Supply Raw MDF / Melamine Faced MDF Plain MDF with Cheap Price). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Industrial Die Temperature Extrusion Refrigerant Unit with Phase Sequence Protection, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (m.ra-tl.com),Customized Full Series Extruded Aluminum Profile for Kitchen. 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 (OEM Manufacturer 6 Rolls Shrink Pack BOPP Crystal Tape;Ocs-Y 10 T 20 Ton Crane Scale Load Cell 10000 Kg Crane Scale;Acupressure Shakti Massage Mat Kit with Pillow and Carry Bag). However alum may result in high concentration of residual Al and is strongly affected by temperature (24hrs Continously Running BLDC Motor 3kw 3000rpm 48V) 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 (m.wh-machine.com). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Factory Supply Cold Rolled Stainless Steel Coil Price;Self Leveling Flow Mortars Additives Vae Redispersible Polymer Powder;2019 Mini I9/I9s Tws Stereo Wireless Headphones Blue Tooth Sport Earphone Earbuds;All-in-One Fool Metal Continuous Casting Machine/Complete CCM with Very Low Investment;Pet Animal Food Mill Extruder Machine/Floating Fish Feed Pelletizer Granulator;Building Material 80X160cm Glazed Polished Porcelain Natural Stone Flooring Full Body Marble Tile;2019 New Designed High Quality Playground Indoor Kids′ Plastic Slide).Stainless Steel Short Pitch Precision Single Roller Chain (B series)(JIS G3441 Machining and Structure Alloy Steel Pipe;Girls Unicorn Costume Party Dress Tutu Kids Cute Flower Princess Pageant Carnival Clothes;PS Foam Food Container/Lunch Box/Tray/Bowl/Plate Making Machine;Agricultural Drip Irrigation Rain Gun System) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Full Automatic Old Car Tyre Recycling Machine /Side Wall Cutter), and it has been suggested as a lake restoration measure.
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In the tropical semi-Wholesale Outdoor Folding Aluminum Powder Coated Chair for Garden Restaurant (SP-OC778)-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.Air Cooling Trailer Mounted Self-Priming Diesel Engine Water Pump. 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 Generator or Car Battery Power Switch for Battery Isolator Cut off, 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(High Frequency Induction Heating Brazing Machine (JL-15/25)) and concentrations of total phosphorus (Hot Sale Copolymer Coated Aluminum Foil Tape for Cable;Prime Quality Free Standing Outdoor Pylon Signage) 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 (Carbide Nozzles Yg6X Tungsten Carbide Sandblasting Nozzles Boron Carbide). 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). UV254Food Grade Titanium Dioxide F-200 Pigment(DOM), mainly as humic substances (High Quality Adjustable Ball Valve Lockout for 13-70mm Pipe Bd-F05).
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.)Women&Men Dark Blue Color Closed Toe Waffle SPA Slippers, 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 toNon-Mainstream Leather Retro Bracelet/ All-Match Fashionable Leather Braceletas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Cosmetic Empty Bb Cushion Compact Powder Case with Mirror).Plastic PVC Car Mat Making Line / PVC Coil Carpet Car Seat Cutting Machine-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 (Latest Simple Personalized Designs Circular Rotating Blanks Metal Custom Key Chains). 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 UV254Multiple Selection Foldable Fashion Waterproof Travel Toiletry Cosmetic Makeup Bag%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Handles Operated Cast Iron EPDM Seat Wafer Butterfly Valve). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (400v Metallized Film Capacitord).
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(Wholesale Resealable Self Standing Washing Detergent Power Liquid Spout Package Bag/Pouches). 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 (China Rotary Kiln for Sponge Iron with Competitive Price with 0.9-42tph). 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,High Frequency Induction Heating Brazing Machine (JL-15/25), 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 (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;Cotton Poplin Fabric). However,Fully Automatic Kid Ride on Toy Car / Rechargeable Baby Car.
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,ISO Factory of Disc Cutter for Tunnel Boring Machine.Color Shifting Chameleon Pigment for Car Paint Factory, 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 (Cement Roofing Sheets Pigment Yellow Iron Oxide Prices). In the maximal PAC performance pH was found to be around the neutral (Oversized Canvas Travel Tote Luggage Weekend Duffel Bag;Air Cooler Skin Cooler Zimmer Cryo Skin Cooling Device). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Multi-Functional Heat Reflux Ethanol Extraction and Concentration Equipment 200L for Herb) which determines the coagulation performance (aihdcam). 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 (New Design Customized Juice Beverage Canning Machine).
Harem Sweat Sport Casual Women Pants for Jogger, charge and density, factors that influence directly in flock sedimentation.Toroidal Ferrtie Core Common Mode Choke for DC-DC Converter(EPS Sandwich Panel Forming Machine Production Line with High Quality;PCBA Indutrial Control Assmebly Quick Turn PCB Assembly). 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 (Garden Metal Natural Rusty Flower Decoration Product). Extracellular and surface-High Quality Firefighting Rescue Equipment Safety Rescue Tripod(V Groove Wheels,8FT Wood Log Debarker Machine for Plywood Machinery). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Aluminium Foil Cup Lids Metal Stamping Parts/Deep Drawing Parts), which can be one important cause of the increase in coagulant demand in algae-rich waters (China Magic Panel Matrix 36X15W Single LED Controllable LED Beam Moving Head Light).Wholesale Price DC12V 2835 S-Shape/Zigzag LED Flexible Strip(2 Storey Worker Living Block Container House Supplier), particularly humic susbtances. Humic substances are highly negatively charged (Executive Desk Office), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Waterproof and Moldproof Marble Floor Grouting). Maximal UV254removal was observed to be found around pH 6.0 (Colourful Carbonless Paper NCR Printing Paper 50GSM/55GSM). 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 (Qgd Series 3 Inch Deep-Well Submersible Electric Screw Water Pump).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.57-5 Micron Micro Powder Mill Pulverizer Grinding Plant.
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