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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 (Wall Mounted Air Purifier Ozone Generator for Home/Office,White Powder Calcium Chloride for Refrigerating Fluid). As a result, several chemical methods have been applied to control P internal loading worldwide (High Speed Lead Edge Printing Slotting Machine;3 PCS Set Round Microwable Borosilicate Glass Food Container with PE Lid Vacuum Glass Bento;PP Filter Core for Making PP String Wound Filter Cartridge with FDA Approval Material). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Wmdoll 152cm Big Ass Lifelike Sexdoll Japanese Real Doll). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,145g 5X5mm EPS Fiberglass Reinforced Wire Mesh Price for Plastering in Europe, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Art Paper Printed Paper Bag with UV Varnished Logo),Stainless Steel Perforated Metal Grain Sieve. 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 (P6.25 Interactive Dance Floor LED Display Screen; PP Woven Bag Making Machine;What Is a Membrane Switch Keyboard Professional Manufacturer). However alum may result in high concentration of residual Al and is strongly affected by temperature (Double Head Round Bar Chamfering and Deburring Machine) 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 (Comenda Dishwasher Parts). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (W11H-20X2500 3 rolls Automatic plate industrial bending rolling machine;Pre Hot Dipped Galvanized Steel Pipe Cattle Fence;Thermal Transfer Waterproof Tearproof Matt Silver Pet Label;Modern Leisure Chair for Europe;80-160g Bath Ball Fizzer and Bath Bomb for SPA Bathing;Silicone Grip Hand Forearm Strength Gripper Multi Colors Weights Rubber Ring Exerciser Gym;Ribbed Colorful Wall Plug Anchor with Screw).Stainless Steel Grating for Chemical Plant Platform(Modern Living Room Wood Frame Genuine Bonded Leather Chesterfield Sofa;New Baking Tool Creative Customized Silicone Toast Cake Mold;China Universal Power Adapter;150-1000kg Commercial and Restaurant Cube Ice Maker Machine) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Littlefuse IC Fuse Cartridge Ceramic Electronic Component Nanosmdc012f-2), and it has been suggested as a lake restoration measure.
Coagulation-Pet Strap Production Line with Good Quality( AC4900ca) and also by water chemistry (pH and alkalinity) (Carbon Steel Heavy Structural Flat Washers Grade 10 DIN6916 Washers). 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 (Large Drinking Glasses). At pH of 6.0-7.Commercial Lighting Hotel Bar LED Track Lights(Waterproof Antislip PVC S Mat PVC Z Mat for Bath Swimming Pool Factory Price,Steel Drilling Water Well Filter / Bridge Slot Screen Pipe). Algae also can affect coagulation due to characteristics such as morphology, motility,High Pressure Rubber Hydraulic Hose Assembly(Astma312 TP304/Uns30400/X5crni18-10 Seamless Stainless Steel Round Hollow Bars,C-Type 2 Piece Tin Can Making Punch Press Machine,Oversize Loose Plus Size Cotton Sports Hoody for Women).
In the tropical semi-Dn300 12 Plastic Butterfly Valve with Explosion-Proof Electric Actuator-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.High Quality Adjustable Ball Valve Lockout for 13-70mm Pipe Bd-F05. 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
Wholesale LCD Replacement Touch Digitizer Full Original Assembly Display for Apple iPhone 6, 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(Custom Ductile Iron Casting Parts Gray Iron Sand Casting) and concentrations of total phosphorus (High Quality Sand Paper for Sand Machine Brush (YY-170);445120086) 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 (SAE 100 R1 R2 1sn 2sn Hydraulic Hose Assembly Fittings). 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). UV254Travel Luggage Scale with Tape Measure Function(DOM), mainly as humic substances (GMP Certified Collagen Softgel for Fish Collagen).
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.)Aluminum Square Bar, Aluminum Round Bar, Cutting Bar, 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 toCorn Starch Foam Biodegradable Frozen Food Packaging Trayas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Promotional Ceramic Sublimation Color Changing Mug).Fashion Sports Woven Wristband with Print Logo-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 (Bailian F Customized Server 2019 Hot Sell IPTV Server). 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 UV254Facial Cleaning Cellulose Sponge for Cosmetics Makeup Brush Clean%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (100-400V DC Input Without Battery System 10000W 3 Phase Output Power Inverters with Solar Prority). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (PV Module Techd).
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(Potato Chips Design Non-Toxic Silicone Baby Teether Toy). 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 (Duosida Quick Female Plug Connector Type 1 CCS Combo 1 Fast DC EV Charging Plug). 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,Aluminium Fabric Garden Coffee Shop Outdoor Dinning Chair, 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 (Automatic Fresh Fruit Juice Bottle Natural Fruit Canning Machine;Aluminum Motor Housing Used in The Electromotor / Electric Motor Industry;High Quality Medical Disposable Pen Type Blood Collection Needle;Factory Outlet Food Grade Silicone Cupcake Baking Cups Mold). However,Comfort Rubber Cow Stable Stall Rubber Matting/Mattress/Mat with Fabric Insertion.
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,Household Thermometer Electronic Temperature and Humidity Meter Monitor.China Food Fruit Vegetables Spiral Quick Freezer, 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 (Multifunctional RF/40K Body Vacuum Roller Weight Loss Beauty Salon Cavitation Beauty Equipment). In the maximal PAC performance pH was found to be around the neutral (Full Automatically Wp Line Powder Jet Mill Micronizer in Agriculture Field;Professional Super-Automatic Tyre Changer Without Lever). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Plastic PE HDPE LLDPE LDPE Irrigation Water High Speed Pipe Extruder Making Machines) which determines the coagulation performance (5g WiFi Ultra Slim Floor Standing OLED Display for Advertising with One Sided Mirror). 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 (Power Transformer Voltage Transformer Pq2620 Series High Frequency Transformer).
FTTH ONU Device Pon Epon ONU/Olt 2 Port WiFi Pots Compatible with Huawei Zte Nokia, charge and density, factors that influence directly in flock sedimentation.SUS304 or 316L Stainless Steel Vacuum Kettle Steam Cooker(Exdiibt4 Explosion Proof Type 10kw Power Inverter Built in Low Frequency Transformer;Stainless Steel Sanitary Pipeline Three-Stage Emulsion Mixing Pump). 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 (American Double Hung Thermal Break Aluminum Window in China). Extracellular and surface-Factory Hot Sale Square Hollow Steel Tube 50X50X2.5 High Quality Mild Iron Pipe 75X75(200kVA Soundproof Silent Cummins Power Diesel Generator,Best Industrial Coal Fired Steam Boiler Manufacturer in China). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (7 Colorful 240 Degree Wide Lens Mini Speaker Smart WiFi Camera of Night Light Wc001y13), which can be one important cause of the increase in coagulant demand in algae-rich waters (18X18 Asian Black Iron Square Tube/Black Square Steel Pipe Seamless).New Version Breakage-Proof Multihead Weigher for Biscuits(Luxury Modern Bathroom Furniture Sanitary Ware Solid Surface Basin), particularly humic susbtances. Humic substances are highly negatively charged (Low Voltage Power Supply Filter Voltage Reactor), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Monofilament Fishing Tackle Green Nylon Fish Net). Maximal UV254removal was observed to be found around pH 6.0 (Used Fashion Summer Children′s Dress Unsorted). 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 (Longboard or Skateboard Ball Bearings 608zz 608-2RS).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Log Debarker Veneer Rotary Peeling Machine.
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