Waste water treatment system

For Hazardous Waste Water, we employ simple but effective physical and electro-chemical methods to eliminate water-borne pollutants.

Our system consists of filtration, electrolytic coagulation, oxidation/UV/ozonation and activated carbon adsorption.

Advantages of our system are:
— simplicity of operation and control of parameters (PLC controlled)
— low cost due to non-reliance on chemical flocculants/coagulants
— coagulants are supplied in-situ inside the electrolytic cell, therefore the storage, handling and purchase of expensive coagulants is no longer required
— use of our proprietary oxidant produces no harmful chemical by-products
— small footprint due to compact design of process equipments/components
— highly efficient removal of contaminants
— minimal sludge produced is chemically stable (passes USEPA TCLP tests)
— can be carried out over a wide range of pH
— the technology used is mature and fully understood

Waste waters may contain a broad array of contaminants such as cyanide compounds, heavy metals, hydrocarbon compounds, oils and fats, surfactants, pathogens, dissolved solids, suspended solids, acids, bases, COD, BOD, and solid debris.

The incoming waste water is first subjected to a physical separation step, preferably with a sand filter system to remove debris, silt and clay particles.To the filtered water stream, we add our proprietary oxidant/catalyst to commence the all-important process of oxidation, after which the waste water is pumped to an electrolytic cell. Many things happen inside the electrolytic cell, which is the main equipment that does most of the job of detoxification and contaminant removal. They are as follows:

  • Under the influence of an electric current, water is decomposed leading to the evolution of oxygen, hydrogen and hydroxyl (OH) ions
  • The hydroxyl ions, in combination with the added oxidants, oxidizes organic and inorganic contaminants into harmless hydroxide compounds
  •  Dissolved metals are reduced into the metallic state at the cathodes and falls to the bottom of the cell as precipitate
  • The anodes releases cations, in this case Fe 3+ cations, which combines with negatively charged anions to form “flocs” which coagulate further into larger “flocs”, for subsequent removal in downstream clarification process as stable hydroxide salts
  • Free cyanide is oxidized at the anode into harmless cyanate, and later into carbon dioxide and nitrogen gas
  • Positively charged ions reacts with negatively charged colloid particles and emulsified oils, allowing them to lose charge and be separated from the aqueous phase by the rising gas bubbles generated from the cell

 

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The electrolytically treated water is then pumped to a sloped plate clarifier, wherein more flocs are allowed to develop. Once the floc have coagulated into bigger sizes, they drop out of solution and deposit unto the sloped plates of the clarifier. The sloped plate clarifier functions like a traditional thickener ten times bigger in size.

As more flocs are deposited on the plates, they slide down by gravity to the sludge collection chamber located at the bottom of the clarifier. The accumulated sludge is periodically removed by pumping these materials to a filter press, wherein the sludge is compacted into a filter cake. The sludge, which contains most of the removed contaminants, is further treated with oxidant, then mixed with water, sand and cement. The mixture is fed to a block making machine as raw material for the production of various concrete products.

After sufficient standing time in the clarifier, the treated water overflows from the clarifier tank as a clear liquid, but may still contain small amounts of contaminants such as pathogenic microorganisms and some recalcitrant chemical compounds. As a precautionary measure, the clarified water will be made to pass through an enclosed channel or conduit equipped with ultraviolet lamps so that the whole water stream can be subjected to ultraviolet (UV) irradiation.

It is well known in the art of water purification that UV is very effective in “killing” bacteria, viruses, cryptosporidium and other life-threatening microorganism in water. UV rays, specially those wavelengths ranging from 200 to 300 nanometers, alter the deoxyribonucleic acid (DNA) of organic microorganisms, impairing their ability to reproduce and cause infections to humans.Another important role played by UV light is the breaking down of strong covalent bonds One of Many Commercial UV Apparatus between components of chemical compounds.
For example, ferrocyanide is very resistant to oxidation. Under the influence of UV light, the bond between iron and cyanide is weakened, permitting the oxidation of iron to iron hydroxide and cyanide to cyanate.

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Although UV is effective as a disinfectant when used alone, its effectivity is enhanced manyfold when used in combination with GeoChem 1 and ozone (O3).

GeoChem 1 and ozone are very strong oxidants by themselves, but it is the hydroxyl (OH) radicals released during the decomposition of GeoChem 1 and O3 that does the job of oxidizing contaminants. UV plays an important part in catalyzing and accelerating the release of the all-important hydroxyl radicals. UV, hydrogen peroxide and ozone together comprise the advanced oxidation system.

Finally the water stream is pumped to a column of activated carbon. Any remaining organic or inorganic contaminants are adsorbed unto the surfaces of the activated carbon, resulting in an almost complete removal of contaminants. It is also in this treatment stage that objectionable taste
are removed from the waste water.

Ozone Machine

Physically, activated carbon binds molecules of dissolved contaminants by Van der Waals force. Molecules of water contaminants adsorb because theforces that keep them in the dissolved state is lesser than the forces on the surface of the activated carbon, which attracts contaminant molecules by forces similar to gravitational forces.

The key to activated carbon’s efficiency as contaminant remover is it’s unbelievable pore surface area. A gram of granular activated carbon may contain a surface area of about 400 square meters, the size of two badminton courts, plus enough space for kibitzers and spectators. Thus, there is a large amount of sites for attracted contaminants to reside over a long period of treatment time.

Pores of Coco Activated Carbon

Aside from physical adsorption phenomenon on the carbon’s surface, chemical reactions also occur, for example the removal of free chlorine by it’s reaction with carbon to form carbon chloride ions .
Waste Water After Treatment
This is the basis for the
removal of objectionable odor, taste and color from contaminated water.

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WASTE WATER TREATMENT
Overview
Wastewater is a costly global problem where our own future depended on it. Wastewater is any water that has been adversely affected in quality by anthropogenic influence. It comprises liquid waste discharged by domestic residences, commercial properties, industry, and/or agriculture and can encompass a wide range of potential contaminants and concentrations. In the most common usage, it refers to the municipal wastewater that contains a broad spectrum of contaminants resulting from the mixing of wastewaters from different sources.
Sewage is correctly the subset of wastewater that is contaminated with feces or urine, but is often used to mean any waste water. «Sewage» includes domestic, municipal, or industrial liquid waste products disposed of, usually via a pipe or sewer or similar structure, sometimes in a cesspool emptier.
The physical infrastructure, including pipes, pumps, screens, channels etc. used to convey sewage from its origin to the point of eventual treatment or disposal is termed sewerage.
It is a must that Wastewater must be treated first before being discharged to the environment.
Methods of Treatment

The treatment of Wastewater can be classified into two (2) broad categories: passive and active treatment methods.

Passive Treatment

In the passive method, water is diverted to an open channel where the acidic water is allowed to react with a limestone bed to neutralize the acidity of the water. Powdered lime is sometimes used instead of limestone. Dolomite can also be used. Variations of the limestone bed are diversion wells and anoxic limestone drains.

In some cases, Wastewater is diverted to engineered wetlands, where an organic substrate promotes chemical and microbial processes that increase the alkalinity of the water.

Passive treatments are the simplest and cheapest methods to treat Wastewater, but are inefficient and fail to address the problem of heavy metals removal and disposal.

Active Treatment

 

Active treatment processes are a more technically-involved method of Wastewater treatment, wherein chemicals are added to neutralize water acidity, as well as to remove dissolved heavy metals and non-metals from the water. Active treatment of Wastewater is a much-more expensive process than passive treatment, the high cost being attributed
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to the capital equipments needed, not to mention the high cost of consumables and other operating costs.

The main advantage, however, is a much higher efficiency of pH neutralization and dissolved solids removal. The reaction product of the chemical reaction, called sludge, is also adequately handled and disposed, which is not possible with passive treatment methods. If the goal of the water treatment efforts is to pass government regulations on effluent quality, then an active treatment method is recommended.

Available Active Treatment Technologies

Active treatment technologies for Wastewater can be broadly classified as;
1) Physical/chemical treatment with mineral precipitation
2) Membrane technology
3) Ion Exchange
4) Biological sulfate removal
The last three methods are very expensive, especially if the amount of Wastewater is huge, which is the case with all mining companies and other heavy industrial park around the world; the first method is the simplest and least expensive, and is the recommended treatment route.

Physical/Chemical Treatment

Physical/chemical treatment methods can be further categorized into two distinct processes:
a) Electrolytic coagulation followed by sedimentation and filtration
b) Chemical coagulation followed by sedimentation and filtration

PROCESS DESCRIPTION

Electrolytic Coagulation (EC)

Under the electrolytic coagulation (EC) method, the main coagulant, the ferric ion (Fe+3), is supplied in-situ by the electrolytic cell itself. When electric current (DC) is passed through the cell, the electrodes, made of ordinary mild steel plates, are dissolved into solution, producing ferric ions. The Fe+3 ions react with the hydroxyl (OHֿ), also produced inside the cell, to produce a precipitate called Ferric Hydroxide (Fe[OH]3). The ferric hydroxide combines with or “captures” the other heavy metal ions to form ‘flocs’ which settle or precipitate out of solution. The treated water is then pumped to an inclined-plate clarifier where the flocs settle, to be later separated from the water by means of a filter press.

Acidity of the water is neutralized by the OHֿ ions; the acidity, represented by the hydrogen ion (H+), reacts with the OHֿ ions and escapes as hydrogen gas (H2) during the process of electrolysis.

After electrolysis when the water is pumped to the clarifier, small amounts of Geogreen Additive2 is added to the treated water in order to effect further removal of sulfates (SO4ֿ²). The CaO in the additive reacts with SO4 to form a precipitate of the mineral

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gypsum, and the tricalcium aluminate in the additive further reacts with SO4 to form the mineral ettringite. In addition, the additive improves clarification rate and helps in producing a more dense, easier to handle sludge.

Advantages
1. Lower operating cost
2. No secondary pollution from chemicals
3. Safer, environmentally acceptable sludge

 

Disadvantages
1. High equipment cost
2. High maintenance cost

Chemical Coagulation

In the chemical coagulation method, Geogreen Additive1 is added to the water, after which the pH is raised to about 6.5 through the addition of lime (CaO). A precipitate of ferric hydroxide (Fe[OH]3) is formed, which also removes other heavy metals from solution through co-precipitation with the ferric hydroxide.

The CaO reacts with SO4 to form a precipitate of calcium sulfate (gypsum). As with the EC process, additive is added to further remove sulfates, in addition to those removed by CaO, through the formation of ettringite.

The sludge which accumulates at the bottom of the clarifier is periodically removed by pumping and dewatered by a filter press; the dewatered sludge is treated with cement and converted into construction material, or disposed of in a landfill.

Advantages

1. Lower equipment cost compared to electrolytic coagulation (EC)
2. Greater control in operating parameters

Disadvantages

1. High cost of reagents/chemicals
2. Large volume of sludge produced

CAPITAL EQUIPMENTS & COST ESTIMATES (depends on the volume of Wastewater to be treated)

Electrocoagulation (EC)

CAPITAL EQUIPMENT COSTS
1. Electrolytic cells and accessories — P xx,000,000.00
2. Inclined plate clarifier and accessories — xx,000,000.00
3. Filter press and accessories — xx,000,000.00
4. Pump, water surge tank and accessories — xx,000,000.00
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5. Civil works and control (PLC) system — xx,000,000.00
6. Professional charges (design and technology) — xx,000,000.00
7. Cement silo — xx,000,000.00
TOTAL P xx,000,000.00

OPERATING COSTS ESTIMATES

Basis: One (1) Eight-hour shift

1. Electricity — Pxx,000,000.00 / year
2. Electrode plate replacement — xx,000,000.00 / year
3. Portland cement — xx,000,000.00 / year
TOTAL Pxx,000,000.00 / year

Chemical coagulation

CAPITAL EQUIPMENT COSTS

1. Inclined plate clarifier and accessories — P xx,000,000.00
2. Filter press and accessories — xx,000,000.00
3. Pump, water surge tank and accessories — xx,000,000.00
4. Civil works and control (PLC) system — xx,000,000.00

 

  1. Cement silo                                                 —              xx,000,000.00
  2. Lime silo                                                     —              xx,000,000.00
  3. Professional charges (design and technology)          —              xx,000,000.00

TOTAL                                    —        P xx,000,000.00

 

OPERATING COST ESTIMATES

 

Basis: One (1) Eight-hour shift

 

  1. Lime                                                           —        P xx,000,000.00/ year
  2. Geogreen Additive 1                                              —              xx,000,000.00/ year
  3. Geogreen Additive 2                                              —              xx,000,000.00 / year

TOTAL                                   Pxx,000,000.00 / year

 

It is hoped that this information could be of help to you in making the choice of treatment method, i.e., whether chemical treatment or electrolytic treatment.

 

 

 

 

 

 

 

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Xerox Phaser 3300MFP_20150409131926_1

 

 

 

 

 

 

 

 

 

 

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