The Term used, as “Wastewater” is often perceived as an undesired left over of an industrial production and brings wide number of questions and problems to the agenda of the staff. The “Wastewater” (WW) is considered as a separate part of the main production and treated as an auxiliary substance in most of the cases. However, it is indeed a part of the entire process and proves its validity and existence when it comes to the discharging point and conditions required.
The hidden value of the WW usually surfaces, upon rounds of investigations and researches for treatment, when it comes to the predestined question of “What is the COST for an Industrial Waste Water Treatment Plant? (AKA WWTP)”
The professionals of several production complexes often find themselves in a tangle once they place the WW under the scope and find out that the issue is more complicated then it appears. This is due to underestimation of the topic and the number of factors that are involved in the system design. In this approach we aim to make an attempt to sort out the factors and point to their impact on the WWTP costs.
What is a WWTP system and comprised of?
Although there may be several ways to describe the process of WW treatment, fundamentally it is the “Separation and removal of the vast number of impurities (The substances that are mixed into the water due to human made processes or natural causes) from the water itself.” Due to this natural fact the WWTP systems encompasses unique and specific equipment necessary to achieve the targets in treatment of the WW. However, the selection of the equipment is heavily dependent of the industrial process (The manufacturing, production lines) and has a direct impact on the costs of the WWTPs.
Below list depicts the main groups of the WWTP components commonly deployed for a wide variety of treatment plants:
- Physical separation; often includes units targeting the removal of solid particles in various forms and shapes, i.e. screens, oil separators, sand removers, coarse filters etc.
- Chemical separation; coagulation, neutralization and flocculation units in combination of clarifiers and/or dissolved air flotation units etc., for removal of the suspended solids and or some dissolved substances (i.e. metals and some ions) and oils.
- Biological units; may be comprised of aerated systems, anaerobic systems, membrane systems, mobilized or fixed bed systems, for removal of organic impurities as well as elements and their compounds such as nitrogen, phosphorus, color, turbidity due to their significant impact on environment.
- Reclamations units; Ultrafiltration, Nano filtration, ion exchangers, activated carbon filtration, sand filters, UV units, chlorination and or ozone units etc.
- Sludge extraction: can include sludge drying beds, centrifugal separators, belt presses or filter presses, bag filters, solar dryers, thickeners for conditioning and dewatering of excess sludge and chemical sludge from clarifiers.
In addition, electrical components, control panel systems, PLC/Scada systems and sub entities of measuring, signaling parts, vessels, piping, pumping, tanks, valves etc., should be considered carefully since the Waste Water is actually is a part of the main production rather than an auxiliary.
The design and assembly of WWTP systems are based on certain criteria. The actual configuration of above components and cost is directly related of the fundamental criteria and, therefore they should be comprehended by the decision-making professionals in order to set the best treatment process and necessary components to achieve the optimum costs.
Cost of WWTP and four main factors that drive;
- The targeted/required level of treatment. This is usually quantified and predefined by the local authorities or world organizations and internal processes if reclamation of water is in question.
- The composition/characterization of the raw WW. This describes the kinds and concentration levels of the impurities in the waste water and measured through required test/analyze method following the main production line trends.
- The amount of WW to be treated. This determines the sizing of the units, components etc. and is the flow rate of the WW in line with the main production line trends.
- Construction materials necessary to ensure the process operation.
Having a good comprehension of above factors would not only provide an efficient view on system design and also understanding the associated costs on the way to owning a correct and functioning WWTP for your needs.
The Target Level of Wastewater Treatment.
In waste water treatment, discharge quality is monitored by several different parameters and the threshold values are generally set by the discharge point conditions. As the number of the parameters change by the type of manufacturing, the pertaining values differ by the conditions of the discharge point. For instance; when general parameters of a food processing plant are COD, TSS, pH, Grease-oil, on the other hand a Surface Plating industry is monitored for COD, Zn, Cu, Fe, pH TSS etc. With the same example if the plant is located in a Industrial zone with a Central WWTP then the allowed discharge parameter values are higher compared to a plant discharging into a receiving environment without a central WWTP between the discharge point and the plant. All these factors directly impact the level of treatment and type of the treatment technology and the associated costs. Understanding the details and differences between the parameter constraints and discharge conditions would enable the investors tremendously in selecting the right technology and magnitude of sizing of a waste water treatment plant.
Construction materials necessary to ensure the process operation:
This subject is another main factor that plays a considerable role in treatment plant costs. Depending on the characterization of the waste water from the manufacturing lines selection of the materials(s) effects the durability of operation, risk of irregular discharge triggered high cost fines, repair costs etc. The waste waters usually are the byproduct of the harsh environments and reflect difficult conditions from the operational aspects. How ever having the right decisions on material may drive the costs down. For instance if the pH values are neutral and the water is not aggressive the Polyethylene tanks instead of Stainless steel may be selected. Or in some cases concrete basins can be more feasible then the steel vessels and show more endurance against the time and ambient conditions.
Other cost components of the waste water treatment plants:
Engineering and Planning of the project
Usually the first step in assurance of an optimum waste water treatment plant is the engineering and the design. This where all categories of factors are carefully put under the scope and evaluated and considered. The planning, selection of the technology, layout, the treatment levels down to the regulatory discharge conditions are done in this phase. Engineering covers all phases of the entire project and is usually 15-25% of the project costs. A careful engineering can optimize the process, electrical, mechanical, and civil- construction costs.
Location vs Space requirements
Although the sizing of a waste water is driven by the flow rate, concentration of pollutant parameters and the regulatory discharge limits, keen consideration of the space conditions may be imperative for the project. The lack of space or the cost of property may bring the project to a crunching point. Selection of the technology and or they of construction by the material selections may reduce the footprint of the waste water treatment plant.
Installation Conditions and Labor rates
Labor costs may present a variety of figures depending on the type or the expertize requirement of the installation of the vessels, units, pumps and all electrical components of the treatment plant in connection with the physical location of the plant. When building a treatment plant with high level of expertise requiring component may drive the labor costs up if the plant is located where no such expert labor exist. Moving labor to far locations is usually expensive and can take a portion as large as 40 % of the project. Instead, the plant may be made of premanufactured and assembled in location at a simpler level that can be possible with the resident labor skills.
Operational Controls Automation System Level
Depending on the size and technology used the automation and control scenarios vary greatly for the waste water treatment plant. At this point the costs to be incurred by the electrical, automation and instrumentation start to come forward within the budget figures. Initially the control could be evaluated as two simple concept as either full automation (Higher the capex Lower the Opex) or manual control (Lower Capex and Higher Opex) Manual operation and controls can be attractive for small footprint and simple technologies where 1 or 2 staff operation is sustainable however on the down side the system would be at risk of human errors and costly fines that the error can expose. On the other hand large treatment plants, nevertheless, would require a minimum number of staff and due to foot print will require automation and instrumentation of the process because of access to the critical points of the units. In such wide spread plants the operation of the process is high value and cannot be compromised and left open to the human errors. Results could be devastating magnitude.
Pre-Manufactured Package Systems
Although the design of waste water treatment plants are driven by the flow rate and the characteristics of the waste water and the discharge conditions, a flexibility may exist in some particular cases. In cases when high flow rate and high pollution load is not the subject the waste water treatment may be handled by pre-manufactured units such as skids and/or containerized form. This opportunity may present savings in on site construction time, labor, material and space.
Operational Consumables and Expenses
In waste water treatment plants operational cost can dramatically affect the selection of technology and associated sizing. This subject should be considered even from the design phases. Due to the nature of the process operational cost is comprised of several interrelated components and therefore it should be evaluated by the comparison of initial versus long-term investment values
Costs incurred by the laws
By the concept the waste water treatment plants are subject to discharge quality standards. When not in compliance the fines can grow up and may be punishable with imprisonment, partial or full time production shutdowns and high fine rates.
Waste disposal costs
As the waste water arrives with pollutants and impurities within, the process of waste water treatment is about removing these from the water where there are some byproducts accumulate on site as to be exported to a storage facility or further handling site such as incineration and or animal or agricultural feed plants.
Regardless of its nature these surplus material such as sludge cakes or variety of other materials will require a considerable budget to export, hauling and/or permits to remove from the site and therefore should be foreseen in financial planning.
Technology dependent other costs and fees
As much as gathered the above are the main groups of factors contribute to the general Capex and Opex of waste water treatment plants,
However there may be hidden costs may come to stage depending on the technology used, geographic location of the plant, discharge location specialties etc. Care should be taken in searching of the unique points regarding the project and consulting with the expert engineers and designers would save the day for these kinds of uncommon and hidden costs.
