Waste Minimization

Waste Minimization

Waste minimization is a practice or process through which the quantity of generated waste is reduced with the main objective of producing the least of unwanted by-products through the optimal use of raw materials, water and energy which in turn reduces the amount of waste entering the environment. It supports any company’s aim for a “Clean technology” production which means full utilization of resources, cost savings in storage, treatment & disposal of generated waste by reducing its volume and its strength or concentration, improves environmental compliance, ensures profit, and promote corporate good image.

For any company which is competing in today’s world, efficient and “clean” processes have become a necessity which not only involves maximization of all the resources and utilities, but also the minimization of waste products. This results in a more cost effective production and plant operation. This activity of waste minimization can be classified under Corporate Social Responsibility Activities and thus, greatly help in boosting a company’s reputation in the society due to which it should be one of the prime focal points for any company’s top management.

The process of waste management in a company can be initiated through the formation of a team/committee consisting of people within the company who are solely dedicated to reduction of waste management within the company. This team then conducts various audits to track the amount of waste being generated through various operations and accordingly comes up with a detailed plan to minimize it. This includes reduction in effluent production, cutting down costs by conservation of water & energy and even resource optimization to minimize wastage. These plans, once approved by the top management of the company, are communicated throughout the company and are encouraged to implement them for minimum waste generation. The progress in tracked through keeping a tab on the amount of waste being generated and comparing pre-implementation and post implementation waste generation and required improvements are made in the plan. This creates an efficient feedback loop for progress tracking and also helps with the enforcement of the plan.

Techniques for Efficient Waste Minimization:

Waste as defined (in the Local Order) is “any matter whether solid, liquid, gaseous or radioactive which is discharged, emitted or disposed in such volume or manner as to cause an alteration to the environment as well as any otherwise discarded, rejected, abandoned, unwanted or surplus matter that can be recycled, reprocessed, recovered or purified by a separate operation or process from that which was produced and even any matter prescribed to be waste and as defined by a competent department.” A waste, therefore, is an excess material resulting from any activities which is discharged as reject and unwanted or any surplus material whether as a total useless matter or those that can be rendered useful again by recycling, treatment or recovery thru a different process from which it was originally produced. Waste materials generated from manufacturing, processing & services from any industrial and commercial activities can be identified and grouped as follows:

  • Off-specification raw materials (contaminated, expired or outdated)
  • Off-specification spoiled products unfit for use or consumption
  • Contaminated products, including spills and leakages
  • Spent auxiliary materials (catalysts, solvents, filters, absorbents, etc.)
  • Undesirable by-products from maintenance activities (oils, solvents, etc.)
  • Undesirable products resulting from commissioning, start-up or process upset
  • Process waste water, including cooling & rinse water contaminated with chemicals
  • Air emission from the process, including fugitives & dust
  • Solid off-cuts, trimmings and excess materials
  • Used container & packaging materials

Ever since the Kyoto Protocol has been put into effect and widely accepted by countries all over the world, the organizations within these countries have become more vigilant about the emissions as well as managing the waste generated which in turn has led to a greater shift in focus for these organizations towards their CSR initiatives and has amplified the need of Waste Management tremendously.

RO/DI Water Systems

RO/DI Water Systems

RO/DI stands for Reverse Osmosis and Deionization. The product is a multi-stage water filter, which takes in ordinary tap water and produces highly purified water.

Tap water often contains impurities that can cause problems. These may include phosphates, nitrates, chlorine, and various heavy metals. Excessive phosphate and nitrate levels can cause an algae bloom. Copper is often present in tap water due to leaching from pipes and is highly toxic to invertebrates. An RO/DI filter removes practically all of these impurities.

There are typically four stages in a RO/DI filter:

  • Sediment filter
  • Carbon block
  • Reverse osmosis membrane
  • Deionization resin

If there are less than four stages, something was left out. If there are more, something was duplicated.

The sediment filter, typically a foam block, removes particles from the water. Its purpose is to prevent clogging of the carbon block and RO membrane. Good sediment filters will remove particles down to one micron or smaller.

The carbon, typically a block of powdered activated carbon, filters out smaller particles, adsorbs some dissolved compounds, and deactivates chlorine. The latter is the most important part: free chlorine in the water will destroy the RO membrane.

The RO membrane is a semi-permeable thin film. Water under pressure is forced through it. Molecules larger/heavier than water (which is very small/light) penetrate the membrane less easily and tend to be left behind.

The DI resin exchanges the remaining ions, removing them from the solution.

There are three types of RO membrane on the market:

  • Cellulose Triacetate (CTA)
  • Thin Film Composite (TFC)
  • Poly-Vinyl Chloride (PVC)

The difference between the three concerns how they are affected by chlorine: CTA membranes require chlorine in the water to prevent them from rotting. TFC membranes are damaged by chlorine and must be protected from it. PVC membranes are impervious to both chlorine and bacteria.

Reverse osmosis typically removes 90-98% of all the impurities of significance to the aquarist. If that is good enough for your needs, then you don’t need the DI stage. The use of RO by itself is certainly better than plain tap water and, in many cases, is perfectly adequate.

RO by itself might not be adequate if your tap water contains something that you want to reduce by more than 90-98%.

A DI stage by itself, without the other filter stages, will produce water that is pretty much free of dissolved solids. However, DI resin is fairly expensive and will last only about 1/20th as long when used without additional filtration. If you’re only going to buy either a RO or a DI, it would be best to choose the RO, unless you only need small amounts of purified water.

Duplicating stages can extend their life and improve their efficiency. For example, if you have two DI stages in series, one can be replaced when it’s exhausted without producing any impure water. If you have both a 5-micron sediment filter and a 1-micron filter, they will take longer to clog up. If there are two carbon stages, there will be less chlorine attacking the TFC membrane. Whether the extra stages are worth the extra money is largely a matter of circumstance and opinion.

RO/DI capacities are measured in gallons per day (GPD), and typically fall within the 25-100 GPD range. The main difference between these units is the size of the RO membrane. Other differences are (a) the flow restrictor that determines how much waste water is produced, (b) the water gets less contact time in the carbon and DI stages in high-GPD units than low-GPD units, and (c) units larger than 35 GPD typically have welded-together membranes.

As a result of the membrane welding and the reduced carbon contact time, RO membranes larger than 35 GPD produce water that is slightly less pure. This primarily affects the life of the DI resin.

Most aquarists won’t use more than 25 GPD averaged over time. If you have a decent size storage container, that size should be adequate. A higher GPD rating comes in handy, however, when filling a large tank for the first time or in emergencies when you need a lot of water in a hurry.

The advertised GPD values assume ideal conditions, notably optimum water pressure and temperature. The purity of your tap water also affects it. In other words, your mileage will vary.

An RO filter has two outputs: purified water and wastewater. A well-designed unit will have about 4X as much wastewater as purified water. The idea is that the impurities that don’t go through the membrane get flushed out with the wastewater.

There is nothing particularly wrong with the wastewater except for a slightly elevated dissolved solid content. It may actually be cleaner than your tap water because of the sediment and carbon filters. Feel free to water your plants with it.

Zero Liquid Discharge Process

What is Zero Liquid Discharge?

Zero Liquid Discharge (ZLD) is a wastewater treatment process developed to completely eliminate all liquid discharge from a system. The goal of a zero liquid discharge system is to reduce the volume of wastewater that requires further treatment, economically process wastewater and produce a clean stream suitable for reuse. Companies may begin to explore ZLD because of ever-tightening wastewater disposal regulations, company mandated green initiatives, public perception of industrial impact on the environment, or concern over the quality and quantity of the water supply.

The first step to achieving ZLD is to limit the amount of wastewater that needs to be treated. Once wastewater generation is minimized and the volume of wastewater that needs to be treated is known, you can then explore what equipment is needed, which depends on the characteristics of the wastewater and its volume. A traditional approach to ZLD is to use filtration technology, funnel the reject waters to an evaporator, and send the evaporator concentrate to a crystallizer or spray dryer. However, the equipment to de-water the concentrated slurry tends to be very large and extremely expensive, which limits the cost effectiveness to only those with very large waste streams.

A common ZLD approach is to concentrate the waste water and then dispose of it as a liquid brine, or further crystallize the brine to a solid. A typical evaporator uses tube-style heat exchangers. The evaporated water is recovered and recycled while the brine is continually concentrated to a higher solids concentration. Concentrated brine is disposed of in a variety of ways, such as sending it to a publicly owned treatment works, using evaporation ponds in areas with net positive evaporative climates, or by treatment in a crystallizing system, such as a circulating-magma crystallizer or a spray dryer. Crystallized solids can be landfilled or applied to land, depending upon the crystal characteristics.

For over 30 years vapor compression evaporation has been the most useful technology to achieve zero liquid discharge. Evaporation recovers about 95 % of a wastewater as distillate for reuse. Waste brine can then be reduced to solids in a crystallizer/dewatering device. However, evaporation alone can be an expensive option when flow rates are considerable. One way to solve this problem is to integrate membrane processes with evaporation. These technologies are nowadays often combined to provide complete ZLD-systems.

The most common membrane processes used so far are reverse osmosis (RO) and electrodialysis reversal (EDR). By combining these technologies with evaporation and crystallization ZLD- systems have become less expensive. They are however combined differently depending on the circumstances. Together with these components, a variety of other well-known water treatment technologies are used in ZLD-systems for pre-treatment and polishing treatment.

These treatments are:

  • pH adjustment
  • Degasifier
  • mixed/separate bed
  • oil/water separator
  • neutralization
  • oxidation (uv , ozone, sodium hypochlorite)
  • dissolved air flotation (daf)
  • carbon adsorption
  • anaerobic or aerobic digestion

As environmental, political and public health entities place more focus on waste water management, ZLD strategies are more often being evaluated for feasibility in industrial facilities. The ZLD approach taken, however, greatly depends on the quality of water available for use.

ZLD benefits:

  • Reduction or elimination of costly regulatory compliance
  • Reliable chemical/physical processes
  • Small footprint
  • Ease of operation
  • Almost 100% water recovery
  • Almost 100% metals and chemical recovery
  • Modular construction
  • Low costs

Well-designed ZLD system will minimize the volume of liquid waste that requires treatment, while also producing a clean stream suitable for use elsewhere in the plant processes.

Waste Water Treatment Plant

Wastewater Treatment Process

Wastewater treatment is the process of converting wastewater – water that is no longer suitable for use – into water that can be discharged back into the environment. Its treatment aims at reducing the contaminants to acceptable levels to make the water safe for discharge back into the environment.

There are two wastewater treatment plants namely chemical or physical treatment plant, and biological wastewater treatment plant. Biological waste treatment plants use biological matter and bacteria to break down waste matter. Physical waste treatment plants use chemical reactions as well as physical processes to treat wastewater. Biological treatment systems are ideal for treating wastewater from households and business premises. Physical wastewater treatment plants are mostly used to treat wastewater from industries, factories and manufacturing firms. This is because most of the wastewater from these industries contains chemicals and other toxins that can largely harm the environment.

The wastewater treatment is as follows:

  1. Wastewater Collection

This is the first step in wastewater treatment process. Collection systems are put in place by municipal administration to ensure that all the wastewater is collected and directed to a central point. This water is then directed to a treatment plant using underground drainage systems or by exhauster tracks owned and operated by business people.

  1. Odour Control

At the treatment plant, odour control is very important. Wastewater contains a lot of dirty substances that cause a foul smell over time. To ensure that the surrounding areas are free of the foul smell, odor treatment processes are initiated at the treatment plant. All odor sources are contained and treated using chemicals to neutralize the foul smell producing elements. It is the first wastewater treatment plant process and it’s very important.

  1. Screening

This is the next step in wastewater treatment process. Screening involves the removal of large objects that in one way or another may damage the equipment. Failure to observe this step, results in constant machine and equipment problems. Specially designed equipment is used to get rid of grit that is usually washed down into the sewer lines by rainwater. The solid wastes removed from the wastewater are then transported and disposed off in landfills.

  1. Primary Treatment

This process involves the separation of macrobiotic solid matter from the wastewater. Primary treatment is done by pouring the wastewater into big tanks for the solid matter to settle at the surface of the tanks. The sludge, the solid waste that settles at the surface of the tanks, is removed by large scrappers and is pushed to the center of the cylindrical tanks and later pumped out of the tanks for further treatment. The remaining water is then pumped for secondary treatment.

  1. Secondary Treatment

Also known as the activated sludge process, the secondary treatment stage involves adding seed sludge to the wastewater to ensure that is broken down further. Air is first pumped into huge aeration tanks which mix the wastewater with the seed sludge which is basically small amount of sludge, which fuels the growth of bacteria that uses oxygen and the growth of other small microorganisms that consume the remaining organic matter. This process leads to the production of large particles that settle down at the bottom of the huge tanks. The wastewater passes through the large tanks for a period of 3-6 hours.

  1. Bio-solids handling

The solid matter that settle out after the primary and secondary treatment stages are directed to digesters. The digesters are heated at room temperature. The solid wastes are then treated for a month where they undergo anaerobic digestion. During this process, methane gases are produced and there is a formation of nutrient rich bio-solids that are recycled and dewatered into local firms. The methane gas formed is usually used as a source of energy at the treatment plants. It can be used to produce electricity in engines or to simply drive plant equipment. This gas can also be used in boilers to generate heat for digesters.

  1. Tertiary treatment

This stage is similar to the one used by drinking water treatment plants which clean raw water for drinking purposes. The tertiary treatment stage has the ability to remove up to 99 percent of the impurities from the wastewater. This produces effluent water that is close to drinking water quality. Unfortunately, this process tends to be a bit expensive, as it requires special equipment, well trained and highly skilled equipment operators, chemicals and a steady energy supply. All these are not readily available.

  1. Disinfection

After the primary treatment stage and the secondary treatment process, there are still some diseases causing organisms in the remaining treated wastewater. To eliminate them, the wastewater must be disinfected for at least 20-25 minutes in tanks that contain a mixture of chlorine and sodium hypochlorite. The disinfection process is an integral part of the treatment process because it guards the health of the animals and the local people who use the water for other purposes. The effluent (treated waste water) is later released into the environment through the local waterways.

  1. Sludge Treatment

The sludge that is produced and collected during the primary and secondary treatment processes requires concentration and thickening to enable further processing. It is put into thickening tanks that allow it to settle down and later separates from the water. This process can take up to 24 hours. The remaining water is collected and sent back to the huge aeration tanks for further treatment. The sludge is then treated and sent back into the environment and can be used for agricultural use.

Wastewater treatment has a number of benefits. For example, wastewater treatment ensures that the environment is kept clean, there is no water pollution, makes use of the most important natural resource; water, the treated water can be used for cooling machines in factories and industries, prevents the outbreak of waterborne diseases and most importantly, it ensures that there is adequate water for other purposes like irrigation.

In summary, wastewater treatment process is one of the most important environmental conservation processes that should be encouraged worldwide. Most wastewater treatment plants treat wastewater from homes and business places. Industrial plant, refineries and manufacturing plants wastewater is usually treated at the onsite facilities. These facilities are designed to ensure that the wastewater is treated before it can be released to the local environment.

Water Audit

An Introduction to Water Audit in Industries

Water has been an over utilized commodity in the process industry due to its low cost. However, due to increasing environmental regulations and high expectations of environmental performance, water conservation has been on the agenda for industries. Conducting a water use efficiency audit is the first step in determining the most cost effective water conservation projects.
Water audit is the measure of impact the organization has on water resources. Determining an organizations’ water consumption and the amount of water lost from a distribution system is the main aim of Water Audit. Loss of water may be due to leakage and other reasons such as pumping inefficiency, unauthorized or illegal withdrawals from the systems and the cost of such losses to the organization.
Water audit creates a detailed profile of the water distribution system. It maps water intensive units, thus facilitating effective management of water resources with improved reliability. It diagnoses the problems faced to recommend appropriate solutions. It is also an effective tool for realistic understanding and assessment of the present performance level and efficiency of the water management service and the compliance of such a system for future expansion.
Standards and guidelines
Since water is seen as a free commodity there are no specific guidelines available for the same. The Central Water Commission has taken the role to bring out General Guidelines for Water Audit which covers the three main sectors of water use i.e. irrigation, domestic and industrial. These guidelines aim to introduce, standardize and popularize the water audit system for conservation of water in all sectors and improve the water use efficiency.
Categories of Water Audit
Based on the extent of water consumption, Water Audit can be divided into four categories.

  • Large Water users:These users covers large Industries, Agriculture Municipalities and Metros with consumption more than 15 million litres per day.
  • Medium Water Users: These users covers Industrial clusters, Medium Industries and township with demand ranging from 3 million litres per day to 15 million litres per day.
  • Small Water Users: Large Hotels, IT Parks, Theme Parks, Industrial and Private Township with demand of 0.5 million litres per dayto 3 million litres per day.
  • Tiny water Users: All other users with consumption less than 0.5 million litres per daysuch as Commercial complexes, Government Offices/Buildings, Builders, Colonies etc.

Benefits of water audit
Water audit improves the distribution system, spots problems and risk areas and therefore builds a better understanding of water handling system right from source to disposal/treatment. Leak detection programs help in minimizing leakages and tackling small problems before they become major ones. These programs have the potential to-

  • Reduce water losses
  • Improve financial performance
  • Improve reliability of supply system
  • Enhance knowledge of the distribution system
  • Increase efficiency in the use of existing supplies
  • Create Better safeguard to public health and property
  • Improve public relations
  • Reduce legal liability, and reduced disruption.

Efficient use of water can be a part of the environmental strategy of a business, just like reducing the carbon footprint. Analyzing risk and opportunities associated with water allow organization to assess water related risks and opportunities. Water audit is qualitative and quantitative analysis of water consumption and it also help to assess significant social and environmental impacts associated with water scarcity.

Aeration in Wastewater Treatment

The Role of Aeration in Wastewater Treatment

Industrial wastewater treatment is the process used to treat wastewater that is produced as a by-product of industrial or commercial activities. After treatment, the treated industrial wastewater may be reused or released to surface water in the environment.
What is Aeration?
Wastewater aeration is the process of adding air into wastewater to allow aerobic bio-degradation of the pollutant components. It is an integral part of most biological wastewater treatment systems. Chemical treatments make use of chemicals to react and stabilize the contaminants in the wastewater stream whereas biological treatments use microorganisms that naturally occur in wastewater to degrade contaminants.
When is Aeration Used?
The activated sludge process is the most common option under the secondary treatment used in municipal and industrial wastewater treatment. Aeration is part of the secondary treatment process. Aeration in an activated sludge process is based on pumping air into a tank, which promotes the microbial growth in the wastewater. The microbes feed on the organic material, forming flocs that can easily settle out. After settling in a separate settling tank, bacteria forming the “activated sludge” flocs are continually circulated back to the aeration basin to increase the rate of decomposition.
How does Aeration Work?
The bacteria in the water require oxygen for the biodegradation process to occur. Aeration provides oxygen to bacteria for treating and stabilizing the wastewater. The bacteria in the wastewater break down the organic matter containing carbon to form carbon dioxide and water utilizing the supplied oxygen. Without sufficient oxygen, bacteria are unable to biodegrade the incoming organic matter in a reasonable time.
In the absence of dissolved oxygen, degradation must occur under septic conditions that are slow, odorous, and yield incomplete conversions of pollutants. Under septic conditions, some of the biological process converts hydrogen and sulphur to form hydrogen sulphide and transform carbon into methane. Other carbon will be converted to organic acids that create low pH conditions in the basin and make the water more difficult to treat and promote odour formation. Biodegradation of organic matter in the absence of oxygen is a very slow biological process.
There are two common types of water aeration: subsurface and surface.
What is Subsurface Aeration?
Subsurface is the most common type of aeration. Large wastewater treatment plants in urban areas commonly use it. Subsurface aeration uses porous devices that are placed below the liquid’s surface. These diffusers or submersible aerators are lowered into the water or fluid and compressed air is released, creating bubbles. This method delivers the most oxygen available into the water and ensures the water and oxygen are thoroughly mixed.
What is Surface Aeration?
Surface aerators push water from under the water’s surface up into the air, and then the droplets fall back into the water, mixing in oxygen. The jets of water break the surface with varying degrees of force.
Why is Aeration Important for Wastewater Treatment?
Aeration is the most critical component of a treatment system using the activated sludge process. When properly implemented, aeration also eliminates seasonal problems such as algae growth or stratification. When exposed to heat and sun, still bodies of water such as reservoirs become stratified. This causes problems, such as foul odors, weed and algae growth, and fish kills. By improving the nutrient-oxygen balance, aeration helps improve water quality. A well-designed aeration system has a direct impact on the level of wastewater treatment it achieves. An evenly distributed oxygen supply in an aeration system is the key to rapid, economically viable, and effective wastewater treatment.

Process Engineering: An Overview

Process Engineering focuses on design processes, operation, process control, and process optimization. This discipline of engineering may focus on physical, chemical, or biological processes. Process engineering encompasses a large array of different industries and sectors. It has a wide range of applications, considerable potential value, and diverse methods.

Process engineering, as a discipline, can be traced back to the era of the 60s, when the term was first coined. However today, this engineering field has gained popularity across the globe. Numerous companies offer Process Engineering services. It is an active area for research, study and application. Process engineering has effected positive change on a global scale.

Since Process Engineering has a broad range of applications in various industries and sectors, the specifications in analysis varies with each sector. Process engineering have various sub-disciplines. Experts usually specialize in one or two of these sub- disciplines.

Process Design – Process design looks at the way the process in question has been designed and set up. It looks for ways to improve this design and structure, and may utilize hierarchical decomposition flow sheets, attempt superstructure optimization, or study plants with multi-product batches. Poor, inefficient design and structure elements can then be removed and substituted with design components that optimize the system better.

Process Operations – Process operations looks at the way the process in question is being executed. It may incorporate real-time optimization or fault diagnosis in an effort to improve operations efficiency. It may also study the operation’s schedule and examine multi-period planning, and other relevant data.

Process Control – Process control concentrates on the reliability of the process. It often employs tools such as controllability measures, robust control, model predictive control, statistical process control, and process monitoring to name just a few. By improving control over the process more consistent, dependable results are gained.

Supporting Tools – Supporting tools in process engineering focuses on the ancillary tools and systems that help support the primary process. These tools may include things such as equation based process simulation, AI or expert systems, sequential modular simulation, global optimization, large-scale nonlinear programming (NLP), optimization of differential algebraic equations (DAEs), and mixed-integer nonlinear programming (MINLP). These supporting tools enhance the overall productivity and quality of the process.

Process engineering is beneficial to industries in various ways. They include everything from debottlenecking certain key problem areas, improving production speed, eliminating unneeded steps from a process, making the process or system safer, and increasing the quality, consistency, and/or volume of output. By and large process engineering provides a way for industries to reduce their costs while increasing the overall efficiency of their processes.

Process engineering has an incredibly far-reaching impact and potentially holds promise for nearly any industrial or commercial business. It is also at the forefront of expanding what is possible in the sciences and technology sectors. Some particular industries served by process engineering include:

  • Chemical
  • Petrochemical
  • Refining
  • Food and food processing
  • Manufacturing
  • Mineral processing
  • Medical
  • Pharmaceutical
  • Bio-techs
  • Biomedical
  • Textiles
  • Transportation

Process engineering is a fast-paced, dynamic discipline that is continually evolving and pushing the envelope of what is possible. Panorama provides a thorough professional service that covers each step of process engineering. With roots in Chemical and Pharmaceutical industry, Panorama provides the best service.

Reducing Energy Usage in Wastewater Treatment

Water and wastewater systems are significant energy consumers with the treatment of water and wastewater. Water shortages, higher energy and material costs, and a changing climate are growing issues of water-energy usage. It is in the best interest for utilities to find efficiencies, both in water and energy use. Performing energy audits at water and wastewater treatment facilities is one way can identify opportunities to save money, energy, and water.

Water and waste- water facilities can be among the largest consumers of energy in a community due to the constant use of pumps, motors, and other equipment operating 24 hours a day, seven days a week,

There are many ways to reduce energy consumption, which can improve the bottom line or provide regulatory-rate relief. The following suggestions will benefit now or in the future to reduce their carbon footprint.

Operational Changes

Facilities should regularly evaluate the condition, performance and remaining useful life of process equipment. Aging equipment is more inefficient, can be costly to repair, and typically requires more energy than newer models. Given that the process that consumes that largest amount of energy in a wastewater treatment plant is the aeration step, this should be a starting point for efficiencies. For a wastewater treatment plant, the multitudes of motors and pumps are dynamic and tend to fall out of calibration over time. To maintain their optimal performance, facilities should be recommissioned every three to five years

Optimize Aeration

Energy saving can be found by installing alternative aeration systems. These systems usually account for more than 50% of a facility’s total electrical consumption. Blowers are a high efficiency and low cost upgrade for existing wastewater treatment plant installations. Upgrading blowers and air distribution systems will decrease the electricity consumption.

Renewable energy

Converting wastewater into renewable energy will help to increase energy efficiency. An anaerobic digester produces methane that can be then utilized in a system to supply energy to the facility at significantly lower costs. The overall cuts on energy costs can enable the facility to become more self-sufficient.

Energy monitoring system

Energy monitoring is a simple and cost-effective way to reduce energy consumption. Wastewater treatment plants can install low-cost wireless submeters to help facilities gather additional consumption data. This information can be analyzed with one of the many available energy information software products to provide a thorough picture of energy use and help staff optimize facility performance

Educate Employees

Educating treatment system operators in the relationship between energy efficiency and facility operations is key to meeting energy targets and finding new opportunities for efficiency. Engaging operators in the process by asking for input results in efficiency measures being suggested and embraced. After all, throughout all stages in the facility, it’s the staff that is dealing with the processes every day.

Energy Audit

Lastly, plants wanting to reduce energy can first benchmark their energy use, then perform an energy audit to see how they can operate more efficiently, and finally, implement the audit’s recommendations.

Depending on the systems and the processes, various other methods too can be implemented to reduce energy consumption at the plant. Every little effort should be made to turn the planet from brown to green.

Zero Liquid Discharge Water Treatment

Zero Liquid Discharge Wastewater Treatment

Zero-liquid discharge (ZLD) is a water treatment process in which all waste water is purified and recycled; therefore, leaving zero discharge at the end of the treatment cycle. ZLD is an advanced wastewater treatment method that includes ultrafiltration, reverse osmosis, evaporation/crystallization, and fractional electro deionization.

Applications of ZLD:

  • Plant Discharge Compliance
  • Cooling Tower Blowdown
  • Flue Gas Desulphurization (FGD)
  • Gasification Wastewater
  • Coal to Chemicals (CTX) waste
  • IGCC Plant treatment

ZLD Technologies:

  • Falling Film Brine Concentrators
  • Forced Circulation Crystallizer
  • Horizontal Spray Film Evaporator
  • Hybrid Systems with Membrane Pre-Concentrators
  • Biological Treatment
  • Solids Waste Handling

Different ZLD systems:

For over 30 years vapor compression evaporation has been the most useful technology to achieve zero liquid discharge. Evaporation recovers about 95 % of a wastewater as distillate for reuse. Waste brine can then be reduced to solids in a crystallizer/dewatering device. However, evaporation alone can be an expensive option when flow rates are considerable.

One way to solve this problem is to integrate membrane processes with evaporation. These technologies are nowadays often combined to provide complete ZLD-systems. The most common membrane processes used so far are reverse osmosis (RO) and electrodialysis reversal (EDR). By combining these technologies with evaporation and crystallization ZLD systems have become less expensive. They are however combined differently depending on the circumstances. Together with these components, a variety of other well-known water treatment technologies are used in ZLD-systems for pre-treatment and polishing treatment. These treatments are:

  • pH adjustment
  • degasifier
  • mixed/separate bed
  • oil/water separator
  • neutralization
  • oxidation (UV, ozone, sodium hypochlorite) 4
  • dissolved air flotation (DAF)
  • carbon adsorption
  • anaerobic or aerobic digestion

The variation of ZLD-systems are endless

Designing a ZLD System:

Characterizing the waste stream is difficult yet essential when designing a ZLD-system. It is important to start off with a realistic estimate of composition, feed chemistry and flow rate. A poorly described waste stream will likely lead to a design which is far from its optimum.

The system will either be too large and expensive or too small to achieve the required separation. The selection of the waste water flow rate typically determines the size and therefore the initial capital cost of the ZLD-system.

But how does one characterize a waste stream? For existing plants, waste stream compositions can be measured directly, preferably on multiple occasions to characterize a range of compositions.

Depending on the process, the feed chemistry may change occasionally, and it is of great importance that one has this in consideration. The most common measurements today include organics, for example, chemical oxygen demand (COD), biochemical oxygen demand (BOD), total organic carbon (TOC) and inorganics (anions, cations, silica).

General Guidelines:

If the water flow rate is small, not many components are necessary. The following general guidelines are accepted today:

  • Below 10 gpm of feed – crystallizers and/or spray dyers can be combined.
  • 10 – 50 gpm of feed – use a crystallizer alone.
  • 50 – 100 gpm of unsaturated feed – use an RO/EDR/crystallizer combination.
  • 50 – 100 gpm of saturated feed – use an evaporator/crystallizer combination.
  • 100 – 500 gpm of feed – either an RO/crystallizer or an evaporator/crystallizer combination may be the most economical.
  • 500 – 1000 gpm of feed – all three should be used.

Zero liquid discharge technologies help plants meet discharge and water reuse requirements, enabling your business to:

  • Meet stringent cooling tower blowdown and flue gas desulfurization (FGD) discharge regulations
  • Treat and recover valuable products from waste streams
  • Better manage produced water

Panorama offers complete thermal and non-thermal ZLD solutions to manage tough-to-treat wastewaters. Panorama’s solutions can help recover more than 95% of your plant’s wastewater.

Design of Water Reclamation System

Water reclamation systems design

Urban water reuse is a term generally applied to the use of reclaimed water for the beneficial irrigation of areas that are intended to be accessible to the public, such as golf courses, residential & commercial landscaping, parks, athletic fields, roadway medians, etc.

Expanded uses for reclaimed water may also include fire protection, aesthetic purposes (landscape impoundments and fountains), industrial uses and some agricultural irrigation.

Reclaimed water is domestic wastewater or a combination of domestic and industrial wastewater that has been treated to stringent effluent limitations such that the reclaimed water is suitable for use in areas of unrestricted public access. Since most areas where reclaimed water is to be used are designated for public access, protection of public health is the primary concern. Although utilization of reclaimed water will be beneficial, there is no guarantee that this source will provide all the water that is needed or desired.

Highly treated reclaimed water that meets the requirements of these guidelines is a valuable water resource. Wastewater treated to urban water reuse standards may be used in lieu of potable water for agricultural irrigation (feed crops), residential/commercial landscape irrigation, dust control, etc. The reclaimed water system is an integral part of the utility system and provides benefits to both the potable water and wastewater utilities.

Some of the substances that can be removed from wastewater include:

  • Suspended solids
  • Volatile organics
  • Semi-volatile organics
  • Oil and grease
  • Hydrocarbons
  • Metals
  • BOD
  • COD
  • Color
  • Odor
  • Hardness
  • Minerals

Reclamation processes:

Wastewater must pass through numerous systems before being returned to the environment. Here is a partial listing from one particular plant system:

  • Barscreens – Barscreens remove large solids that are sent into a grinder. All solids are then dumped into a sewer pipe at a Treatment Plant.
  • Primary Settling Tanks – Readily settable and floatable solids are removed from the wastewater. These solids are skimmed from the top and bottom of the tanks and sent to the Treatment Plant where it’ll be turned into fertilizer.
  • Biological Treatment – The wastewater is cleaned through a biological treatment method that uses microorganisms, bacteria which digest the sludge and reduce the nutrient content. Air bubbles up to keep the organisms suspended and to supply oxygen to the aerobic bacteria so they can metabolize the food, convert it to energy, CO2, and water, and reproduce more microorganisms. This helps to remove ammonia also through nitrification.
  • Secondary Settling Tanks – The force of the flow slows down as sewage enters these tanks, allowing the microorganisms to settle to the bottom. As they settle, other small particles suspended in the water are picked up, leaving behind clear wastewater. Some of the microorganisms that settle to the bottom are returned to the system to be used again.
  • Tertiary Treatment – Deep-bed, single-media, gravity sand filters receive water from the secondary basins and filter out the remaining solids. As this is the final process to remove solids, the water in these filters is almost completely clear.
  • Chlorine Contact Tanks – Three chlorine contact tanks disinfect the water to decrease the risks associated with discharging wastewater containing human pathogens. This step protects the quality of the waters that receive the wastewater discharge.

At various stages in the multistage treatment process, unwanted constituents are separated using

  • Vacuum or pressure filtration,
  • Centrifugation,
  • Membrane-based separation,
  • Distillation,
  • Carbon-based and zeolite-based adsorption, and
  • Advanced oxidation treatments.

Activated carbon is a highly adsorbent form of carbon that is produced when charcoal is heated. It removes impurities via adsorption from both aqueous and gaseous waste.

Membranes allow materials of a certain size or smaller to pass through but block the passage of larger materials. Imaginative arrays of membrane materials in innovative physical configurations are used to separate unwanted solids and dissolved chemicals from tainted water. During operation, purified water diffuses through the micro-porous membranes and collects on one side of the membrane, while impurities are captured and concentrated on the other side.

Today, membranes made from cellulose acetate, ceramics, and polymers are widely used. The applications come in a variety of innovative designs, including tubular, hollow-fiber, plate-and-frame, and spiral-wound configurations. The goals of membrane design are to

  • Maximize the available surface area,
  • Reduce membrane pore size (to allow for the more precise removal of smaller contaminants),
  • Minimize the pressure drop the fluid will experience when flowing through the unit, and
  • Identify more cost-effective system designs.

The addition of oxidizing agents—chemical ions that accept electrons—has proven effective against these microorganisms like waterborne viruses, bacteria, and intestinal protozoa. Today, a variety of advanced oxidation techniques kill such disease agents and disinfect water, thanks to ongoing developments pioneered by the chemical engineering community.

Historically, chlorine-based oxidation has been the most widely used, and it is very effective. However, the transportation, storage, and use of chlorine (which is highly toxic) present significant potential health and safety risks during water-treatment operations. To address these concerns chemical engineers and others have developed a variety of alternative oxidation treatments that are inherently safer, and in many cases more effective, than chlorination. These include Ultraviolet light,Hydrogen peroxide, and Ozone, each of these powerful oxidizing agents destroys unwanted organic contaminants and disinfects the treated water without the risks associated with chlorine use.

Considerations for constructing a water reclamation system:

In planning for urban reuse there are three major issues that must be considered prior to developing such a system.
The first issue is that year round wastewater treatment and disposal are required when designing any wastewater treatment facility. A water balance for the reclaimed water service area is needed to determine how much wastewater will be generated and how much irrigation demand there is for the reclaimed water. The wastewater generated may exceed the reclaimed water demand during portions of any given year. Therefore, a discharge permit, additional storage, or a designated land application site may be required.

The second issue which must be considered is the constituents (e.g. salts) that may be present in the reclaimed water and what effect(s) they may have on the cover crops that will be irrigated. For specialized users such as golf courses, nurseries, etc., a detailed evaluation of the effluent constituents may be necessary in order to determine whether or not they are candidates for urban reuse irrigation.

Third, Urban Water Reuse is not suitable for all wastewater treatment applications. The manpower requirements and permit reporting can make a reuse facility expensive for a small operation. The facility’s operator in responsible charge shall be a Class I Biological Wastewater Operator. Operation of reclaimed water systems requires on-site operation by a Class II Biological Wastewater Operator or higher operator 8 hours per day, 7 days per week. If the operator can monitor from a remote location and receive immediate notification for alarms, a reduced schedule for on-site operation by a Class II Biological Wastewater Operator or higher operator may be considered on a case-by-case basis.

Deciding how best to use wastewater begins with a laboratory analysis of the substances present in the water. Engineers work with each client to specify the laboratory tests that should be performed. Once that information has been obtained, our engineers and the client:

  • Identify the various ways the water can be used in the specific facility
  • Identify the substances to be removed from the water to make it suitable for each use
  • Determine the process needed to re-condition the wastewater for each use
  • Estimate how much water consumption would be saved by recycling and calculate the annual cost of the water
  • Obtain a cost estimate for the required treatment system
  • Compare the cost savings of reduced water consumption to the capital and operating expenses of the treatment system to determine whether the investment in recycling is cost-effective

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