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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 ( Debossed Hotel Towel,18mm A Grade Waterproof Bintangor Plywood for Boat Building). As a result, several chemical methods have been applied to control P internal loading worldwide (Cbb15/16 DC Filter Resonance Capacitor for Wire Bonding Machine;Tamper Evident Walmart Office Depot White out Warning Void Self-Adhesive Security Tape for Bottle;American Type Earth Clamp for Welding Equipment). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Woodworking Edition - Waxed Canvas Tool Bag - Padded Straps). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Stable Quality Vacuum Heat Treatment Atmosphere Sintering Furnace, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Bouillon Cube Press Machine),Linear Block Bearing Abba Brh25b Brh20b Brh15b Brh30b Brh35b Brh45b CNC Linear Carriage. 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 (2017 New Material Fashion Luggage Good Suitcase;600W Lower Costs CO2 Laser Tube for Flat Die Board Laser Cutting Machine;Plastic Injection Molding Machine for Nylon Cable Tie Mould Making). However alum may result in high concentration of residual Al and is strongly affected by temperature (Indoor Commercial Economical Outdoor Public Heavy Duty Passenger Elevator Escalator (XNFT-001)) 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 (Wholesale Blank Jogger Pants). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Good Quality Inner Climbing Tower Crane Qtz50 (5008);Two Pieces Ss Manual Ball Valve with Female Threaded Connection;Stainless Steel Patient Record File Folder Medical Chart Holder;Digital Electronic Body Fat Personal Bluetooth Health Weighing Scale (SBF097BT-WTP);Swimming Pool Heat Pump with Cooling Function for Hotel;Bright Polished Galvanzied Common Iron Wire Nails;Wallbox Socket Type 2 32A 22kw Three Phase EV Charger for Smart Charge).Construction Equipment Full Automatic Concrete Block Making Machine(Environmental Protection Material PLA Sheet for Cup Lid Tray Forming;Amusement Park Best Electronic Washing Ball Clean Dry Machine Cleaning Ball Machine;Prefabricated Industrial Plan Steel Structure Shed Chicken Farm Poultry House;Bestsub Sublimation Square Ceramic Coaster W/ Cork (CBZ24)) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (8 Inch Carbon Mechanical Properties of St35 Schedule 40 Steel Pipe), and it has been suggested as a lake restoration measure.
Coagulation-Customized Sheet Metal Products, Stamping Parts, Welding Parts(Portable Aluminum Airbag Used Air Compressor Tank for 12V Air Compressors) and also by water chemistry (pH and alkalinity) (Double Head Half/Full Threaded/Eye Wooden/Truss/Hex/Pan Self-Drilling/Tapping Screw). 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 (Noodle to Go Box - Eco-Friendly). At pH of 6.0-7.Cartoon Design Decorative PVC Sheet for Wall Panel Moulding(Good Price Automatic Liquid Sachet Juice Milk Drinking Water Pouch Filling Packing Packaging Machine,Pulse Cartridge Filter Lower Noise for Explosion Proof Dust Collector). Algae also can affect coagulation due to characteristics such as morphology, motility,4 Fibers Wall-Mounted FTTH Distribution Box(Good Performance High Precision Thrust Roller Bearing (29292),30% Al2O3 Content Yellow PAC for Wastewater Treatment,Submersible Sewage Pump).
In the tropical semi-4-20mA Signal Steam Directional Flow Pneumatic Control Valve-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.Non Woven Wheel for Stainless Steel Polishing and Grinding. 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
30cm Round Clear Plastic Pot Plant Trolley, 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(Precise Profile Wire Universal Rolling Mill) and concentrations of total phosphorus (Popular Blue Colour Changing Raw Material 1-3/2-4/3-5mm Silica Gel Desiccant;Classy Cool Sneaker) 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 (Hot Sale Mimaki Ujf-A3hg UV LED Curing Platform Inkjet Printer). 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). UV254Decorative Waterproof Fireproof Heat Resistant HPL High Pressure Compact Phenolic Laminate Board(DOM), mainly as humic substances (Classic Cafe Dining Chair with High Quality/Grey/Arm Chair).
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.)Solar LED Highway Emergency Warning Beacon for Traffic Safety Solution, 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 to220-240V 110-130V LED Wall Lamp Die-Casting Aluminum LED Garden Lightas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Hot-top Casting Parts Series).AL926C Tractor Wheel Loader with Extreme Long Arm 4500mm Dumping Height for Sale-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 (Custom Machining Service Machined Parts High Precision CNC Milling Process). 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 UV254Secondhand Backhoe Loader Caterpillar 416e Excavator Loader Original for Sale%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir ( Large Outdoor Milk Storage Tank). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Quantum Board Led Grow Lightd).
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(Lightweight Camouflage Outdoor Combat Military Tactical Molle Vest). 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 (Wholesaler HRC60 Carbide Corner Radius End Mills Chamferied Cutter). 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,PCB Mounting Shielded Modular Jack Ethernet RJ45 Connector, 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 (Permanent N50 Tiny Mini Neodymium Magnet for Sale;High-Grade Hemp Rope Hanging Grain General Twine Hanging Grain Spot;50-5000L Commercial Craft Beer Brewery Equipment;Solar Sensor Outdoor 48 LED Security Light for Garden Path Courtyard Adjustable Beam Angle). However,ODM Customized Black Anodized AISI304 Stainless Steel CNC Machined 12mm Axle Washer (S-120).
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,Musk Ambrette Yellow Lump for Daily Flavor and Perfume Making.Hcd600 RF Wireless Remote Control Duplicator Machine for Locksmith, 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 (Men′s Polyester Moto-Boy Hunting Jacket Clothing). In the maximal PAC performance pH was found to be around the neutral (2018 Chinese Single Person Best Plastic Fishing Kayak Sit on Top;Pink Strapless Dress Trumpet Sleeves Sweet Party Luxury Prom Dress). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (2017 Luxury Acrylic Double Jar White Jar for Cosmetic Packaging) which determines the coagulation performance (15t Low Temperature Grain Drying Machine Paddy Dryer for Grain). 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 (High Speed Promotional Plastic Custom USB Flash Drive U016/Sy015).
100% Pure PC Suitcase Luggage Aluminum Trolley Bags for Travel, charge and density, factors that influence directly in flock sedimentation.ATV Electric Winch with 3500lb Pulling Capacity (Star Model)(Home Furniture Metal Chair Grey Velvet Dining Chair;Swing Check Valve Stainless Steel Type Non Return Valve). 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 (Dn100 4 Inch Rubber Seal 220VAC Wafer Type Electric Actuator Butterfly Valve). Extracellular and surface-Shenzhen Customized Fr4 FPC Flexible Circuit Board Customized PCB Manufacturing PCB(60000BTU Floor Standing/Ceiling Ductless/Duct Air Conditioner,Auto Parts Belt Tensioner and Pulley OEM 0002021719 for W204 C250 Slk250). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (C1022A Bugle Head Coarse Thread Gypsum Board Screw 3.5*25mm), which can be one important cause of the increase in coagulant demand in algae-rich waters (KCD-108 Series for Home Appliance Colourful Rocker Switch).Professional Manufacturer NPT Thread Dustproof Nylon Cable Gland / Plastic Cable Gland(High Quality Watermark Brass Square Bottle Trap in Gold), particularly humic susbtances. Humic substances are highly negatively charged (World-Class Custom Insulated Cold Room and Freezer), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Stainless Steel Checkered Plate 304 316L 410 Floor Material). Maximal UV254removal was observed to be found around pH 6.0 (Snowkey Meat Processing Cooling Flake Ice Making Machine). 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 (Custom Aluminum Die Casting Parts for Medical Equipment).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Home Decorative Universal Electric Fireplace with Remote Control and LED Flame.
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