Papers by Nikolay Voutchkov
Desalination and Water Treatment, 2009
Seawater desalination plants generate concentrate (brine) which typically has 1.5 to 2 times high... more Seawater desalination plants generate concentrate (brine) which typically has 1.5 to 2 times higher total dissolved solids concentration (salinity) than that of the ambient seawater. When returned to the ocean without dilution, this concentrate may have a negative impact on the aquatic environment in the area of the discharge. The environmental impact of the desalination plant discharge is very site-specific and depends to a great extent on the salinity tolerance of the specific marine organisms inhabiting the water column and benthic environment influenced by the discharge. This work presents methodology that allows establishing the site-specific maximum level of salinity concentration (salinity tolerance threshold) at which marine organisms not only survive, but can also grow and reproduce normally. The described method was used successfully for the permitting of the concentrate ocean discharge of two large seawater desalination projects in California-the 189,000 m³/d (50 MGD) Carlsbad and Huntington Beach desalination plants.
Desalination, Oct 1, 2014
ABSTRACT SEC of TFN RO membranes were compared with TFC RO membranes. • TFN RO membranes exhibite... more ABSTRACT SEC of TFN RO membranes were compared with TFC RO membranes. • TFN RO membranes exhibited up to 10% savings in SEC. • Savings in SEC for TFN RO membranes was due to lower feed pressure requirements. In this study, thin film nanocomposite (TFN) reverse osmosis (RO) membranes were evaluated at a demonstration-scale facility to determine the specific energy consumption (SEC) during seawater desalination. Conventional (same element type within pressure vessel) and hybrid (high and low rejection elements within pressure vessel) configurations were evaluated and compared to commercially available thin film composite (TFC) RO membranes. The specific flux at 25 °C for TFN RO membranes was 1.72 lm −2 h −1 /bar when compared to 1.48 lm −2 h −1 /bar for TFC RO membranes. Utilization of TFN RO membranes resulted in reduced feed pressure requirements when compared to TFC RO membranes, resulting in energy savings up to 10%. In order to achieve the same permeate water quality, the SEC for a 2-pass RO system with TFN RO membrane elements in the first pass was 3.24–3.45 kWh/m 3 . The SEC with TFC RO membrane elements for the same conditions was 3.60 kWh/m 3 . Results presented in this study show a promise for the utilization of TFN RO membranes to reduce energy consumption and minimize operational costs associated with electricity usage.
Desalination, Oct 1, 2010
Two types of pretreatment systems are typically used to protect seawater reverse osmosis membrane... more Two types of pretreatment systems are typically used to protect seawater reverse osmosis membranes from fouling: conventional granular media filtration and membrane filtration. While granular medial filtration is still a dominating seawater pretreatment technology, microfiltration and ultrafiltration membrane systems for seawater pretreatment have evolved rapidly over the past decade and may offer cost and performance benefits for the site specific conditions and challenges of a given seawater desalination project. This article presents a critical review of widely used conventional granular and membrane pretreatment technologies and addresses key factors, and issues which would need to be taken under consideration when selecting a seawater pretreatment system.
Advances in oceanography & marine biology, Jan 6, 2020
Proceedings of the Water Environment Federation, 2005
Primary and secondary clarifiers are inseparable and integral part of every conventional wastewat... more Primary and secondary clarifiers are inseparable and integral part of every conventional wastewater treatment plant. Their performance efficiency is affected by the upstream wastewater collection and treatment facilities and has a significant impact on downstream biological treatment and solids handling facilities. The work addresses the interaction of plant clarifiers with the wastewater collection system, pretreatment facilities, the activated sludge treatment process and the solids handling facilities. More specifically, this work discusses the effect of wastewater collection system type on clarifier design and various means for mitigation of transient flow impact on clarifier performance, such as peak flow reduction measures in the collection system; flow equalization; use of high-rate solids separation technologies; relationship between clarifier depth and its transient flow handling capacity; and mitigation of transient flow impact by monitoring and control of the overall solids inventory in the activated sludge system. The effect on primary clarification on nutrient removal in conventional and enhanced nitrogen and phosphorus removal systems is also discussed and guidelines for clarifier design for chemical and biological nutrient removal are presented. This work also discusses the interaction of plant primary and secondary clarifiers with the sludge thickening, stabilization and dewatering facilities.
Reverse osmosis (RO) system configuration and key design parameters (permeate flux and recovery) ... more Reverse osmosis (RO) system configuration and key design parameters (permeate flux and recovery) are determined by two key factors: (1) the quality of the desalinated water the system has to produce in terms of salt content [total dissolved salts, sodium, chloride, boron]; and (2) the fouling potential of the desalinated water. This chapter presents a brief overview of the purpose and function of the typical components of SWRO desalination systems (high-pressure pumps, RO racks, and energy-recovery system) and the type of RO membranes and membrane configurations that are most frequently applied for seawater desalination. The chapter discusses the impact of each RO-membrane type and system configuration on the pretreatment technology selection. In addition, the chapter outlines most commonly applied methods to control RO-system membrane fouling by using alternative pretreatment configurations. The chapter focuses exclusively on SWRO desalination systems because of their popularity.
This chapter provides a comparative analysis of the key advantages and disadvantages of granular ... more This chapter provides a comparative analysis of the key advantages and disadvantages of granular media and membrane pretreatment filters in terms of the effect of source water quality and temperature on their performance, surface area requirements, quantity and quality of the generated residuals, chemical and power uses, and overall water production costs.
This study compares the performance of high solids centrifuges when processing anaerobically dige... more This study compares the performance of high solids centrifuges when processing anaerobically digested and undigested mixture of primary sludge and waste activated sludge, in order to evaluate the effect of sludge blend ratio on the dewaterability of the sludge. The operational data (full scale and pilot scale) of six selected wastewater treatment plants were analyzed during the course of this study. Three of the six plants dewater anaerobically digested sludge, two dewater raw sludge, and one dewaters both digested sludge and raw sludge in parallel trains. Several key operational parameters including: primary to waste activated sludge ratio, feed rate, polymer dosage, cake solids concentration, and solids recovery were evaluated in order to provide a basis for comparison of the centrifuge performance. The data indicates that the sludge blend (primary to waste activated sludge ratio) has a significant effect on the dewaterability of both digested and undigested sludges. Under similar operating conditions, cake concentration increases with increasing the primary sludge fraction.
Elsevier eBooks, 2018
Abstract Based on the source water salinity they process, desalination plants can be divided into... more Abstract Based on the source water salinity they process, desalination plants can be divided into three main groups: nanofiltration (softening) plants, brackish water desalination plants, and seawater desalination plants. In addition, depending on the number of sequential RO systems for treatment of permeate and concentrate, RO system configurations could be divided into two main categories: (1) single- and multiple-pass RO systems; (2) single- and multiple-stage RO systems. In all types of desalination plants, multiple-pass and multiple-stage RO systems could also be combined into configurations that allow achieving target RO system recovery and product water quality at optimum life-cycle cost of water production. The various types of systems and their practical application are discussed in the following sections.
Water Research, Nov 1, 2019
Membrane biofouling remains a significant challenge in seawater reverse osmosis desalination for ... more Membrane biofouling remains a significant challenge in seawater reverse osmosis desalination for drinking water production. This study investigated nutrient imbalance as the cause of biofouling in labscale experiments and carried out a year-long field-testing at a seawater desalination pilot plant. Lab experiments showed that growth medium with excess of organic carbon (C) but with low nitrogen (N) and phosphorus (P) accelerated the formation of bacterial biofilm. Balancing C to N and P ratios by adding N and P to growth medium increased the proliferation of free-living cells but reduced attached form of bacteria as biofilm. The cell excretion of excess C in the form of extracellular polysaccharides (EPS) was considered as a strategy for nutrient storage for future use. Cell enzyme activity assays indicated some of the bacteria had enhanced enzyme activities to degrade polysaccharides in the absence of organic C in growth medium, possibly using EPS in the biofilm. A year-long field study indicated that accelerated biofouling of seawater reverse osmosis (SWRO) membranes was associated with the elevated content of total organic carbon (TOC) in the intake seawater. Adding N and P to the intake seawater to balance the increase of TOC resulted in reduction of membrane biofouling. Microbial community analysis of the biofouling layer using 16S rRNA gene sequencing indicated biofouling communities varied with seasonal changes. Dosing of N and P did not induce dramatic changes in the fouling microbial community growing on the membrane surface. The outcome of this work implies that membrane biofouling associated with the elevated concentration of TOC in intake seawater is caused by imbalance of C:N:P in the source seawater which occurs often during algal blooms. Addition of N and P to rebalance the nutrients can prevent accelerated SWRO membrane biofouling.
This chapter features a methodology for identifying the type and configuration of the most suitab... more This chapter features a methodology for identifying the type and configuration of the most suitable pretreatment system for the site-specific conditions of a given desalination project. Although the focus of the chapter is seawater pretreatment, the presented methodology can be applied for reverse osmosis desalination plants using brackish surface water. The selection methodology is based on the analysis of the type of intake selected for collection of saline source water and the quality of the intake water in terms of content of particulate, colloidal, and microbial foulants. The presented methodology employs water quality parameters such as turbidity, silt density index, total hydrocarbons, algal content, and total organic carbon, which are commonly used for the design of desalination plants. This methodology is developed based on industry-wide practical experience with the implementation of alternative pretreatment technologies and configurations worldwide over the past 20 years.
This chapter discusses the impact of the type and configuration of the desalination plant intake ... more This chapter discusses the impact of the type and configuration of the desalination plant intake on the selection and design of the pretreatment system. The chapter encompasses practical pretreatment experience with desalination plants using both open intakes and subsurface intakes and contains guidance of how to select intake configuration that minimizes downstream pretreatment requirements for the site-specific conditions of a given desalination project. The chapter analyzes the key advantages and challenges associated with the use open and subsurface intakes and the trade-off between the use of costlier intakes and less complex pretreatment systems and vice versa. The chapter contains design considerations associated with the selection of intake configuration in conjunction and contains cost information for open and subsurface intakes.
Filtration & Separation, Mar 1, 2009
John Wiley & Sons, Inc. eBooks, Dec 29, 2008
Desalination, Apr 1, 2018
Technological advances of membrane seawater desalination have propelled its worldwide use. Despit... more Technological advances of membrane seawater desalination have propelled its worldwide use. Despite the twofold reduction of its power demand over the past 20 years, seawater desalination remains the most energy intensive alternative for production of fresh drinking water at present. This article provides an overview of the current status of energy use for seawater desalination, discusses the minimum energy demand for production of fresh water and presents key factors that influence the desalination plant energy demand for the site specific conditions of a given desalination project. The article describes key benefits and challenges associated with the implementation of energy-saving technologies and equipment such as: collocation of desalination and power plants; alternative RO system configurations proven to yield significant energy savings such as; low-recovery plant design; use of split permeate two-pass RO system configuration; three-center RO system design; and use of high productivity/low energy membrane elements, hybrid RO membrane vessel configurations, large-size high efficiency pumps and pressure-exchanger based energy recovery systems. The article also discusses emerging desalination technologies with high-energy reduction potential and provides a forecast of the potential impact of future technologies on energy use for membrane desalination.
River Publishers eBooks, Sep 1, 2022
Elsevier eBooks, 2017
The purpose of this chapter is to delineate the role of pretreatment in the production of desalin... more The purpose of this chapter is to delineate the role of pretreatment in the production of desalinated water by membrane separation and the impact of pretreatment on reverse osmosis (RO) system productivity and reliability. The chapter describes the phenomena of membrane fouling, scaling, and membrane polarization, the factors impacting the location and magnitude of their occurrence, and their influence on the freshwater productivity of the RO desalination systems. The two types of membrane fouling (internal and external) commonly observed in RO desalination systems are defined and their relation to the need for cleaning and useful life of the membranes is explained. The chapter also focuses on the factors affecting the magnitude and rate of RO-membrane fouling, such as source water quality, pretreatment system performance, and membrane properties (charge, roughness, and hydrophobicity).
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Papers by Nikolay Voutchkov
for system Design anD DeveloPment of turnkey Desalination Projects
May 31– June 1, 2017 Rome, Italy
Lecturers Mark Wilf, PhD, Nikolay Voutchkov, PE
Day 1 – Effective approach to desalination system design
09:00–10:00
Desalination plants configuration and feed water sources
Configuration of brackish RO water desalination systems Con guration of seawater RO desalination systems Configuration of advanced wastewater reclamation systems Feed water supply sources and water quality
Brackish wells Seawater intakes Tertiary effluent
Disposal of RO concentrate
Feed water pretreatment processes and high pressure pumping unit
Pretreatment in RO brackish plants processing well water Pretreatment in seawater RO plants
Pretreatment based on media filtration
Pretreatment based on membrane filtration Pretreatment in wastewater reclamation plants Management of pretreatment discharge residuals High pressure pumping unit
Brackish water RO plants Wastewater RO plants Seawater RO plants
Energy recovery devices Optimization of power usage
Coffee break
RO membranes and membrane elements
Con guration of composite RO membranes and membrane elements Nominal and eld performance of membrane elements
Effect of process parameters on membrane performance.
Management of membrane elements inventory in RO desalination system
10:00–10:45
10:45–11:00 11:00–12:00
12:00–13:00
Design of RO membrane unit
Selection of membrane elements according to application Optimization of membrane array
Recovery rate considerations
Train size consideration
Consideration of product water demand
Design of RO membrane unit utilizing computer projection programs Brackish water RO plants
Wastewater RO plants
Seawater RO plants
Lunch break
Chemistry and configuration of permeate water post treatment process
Chemistry of the post treatment process
Process and configuration of post treatment process
Brackish water RO plants Wastewater RO plants Seawater RO plants
Coffee break
Examples of con guration of commercial desalination plants
Brackish RO–NF water plants Boca Raton, Florida Arlington Desalter, California
Wastewater reclamation plants GWR, Orange County, California Bedok Plant, Singapore
Seawater RO plants Carlsbad, California Tuas, Singapore
Consideration of plant design optimization
Project requirements included in the Project Scope Book Feed water supply and site conditions
Power supply structure
Pilot unit operation
Questions and Discussions
13:00–14:00 14:00–15:00
15:00–15:15 15:15–16:00
16:00–17:00
17:00–17:30
Day 2 – Roadmap to Successful Desalination Project Development
09:00–10:00
Overview of the project development process
Type of project delivery alternatives and role of developer
Initial project prospecting and development – de ning project scope Developing of estimates for costs of water production and water sales Obtaining of project entitlements
Use of plant site
Environmental permitting
Water purchase agreement
Power purchase agreement
Rights of way for access to intake and discharge Rights of way for product water delivery
10:00–10:45
Procurement of turnkey construction and operation contractors Project nancing
Project design, construction, commissioning and acceptance testing Desalination plant asset management during plant operation phase
Key project risks and their effective management
Permitting (licensing) risks
Entitlement risks
Risks associated with power supply and use of alternative power sources Construction risks
Source water quality related risks
Technology risks
Regulatory risks
Operational risks
Desalinated water demand risks
Financial risks
Coffee break
Project Delivery alternatives - role of project developer/owner
Design-bid-build (DBB)
Design-build-operate (DBO)
Build-own-operate (BOO) and build-own-operate-transfer (BOOT) Concession
Initial project scoping and development
De ning product water quantity and quality
Selecting plant site – location, con guration and size Identifying the most suitable type of intake and outfall Selecting key desalination process treatment processes Finding cost competitive power supply sources
Lunch break
Determining water production costs and project funding
Engineering, procurement and construction costs Operation and maintenance costs
Costs of water production
Water sales tariff
Project funding alternatives and their contractual structure
Coffee break
Project permitting – key issues and considerations
Intake permitting issues
Concentrate discharge – challenges and solutions
Product water quality related permitting considerations
Addressing zero carbon-footprint requirements for desalination plants Selecting key desalination process treatment processes
Project development case studies
200,000 m3/d Carlsbad SWRO desalination project, USA 20,000 m3/d Majis SWRO desalination project, Oman
Questions and discussions
10:45–11:00 11:00–12:00
12:00–13:00
13:00–14:00 14:00–15:00
15:00– 15:15 15:15–16:00
16:00–17:00 17:00–17:30
Best Practices for system Design and DeveloPment of turnkey Desalination Projects
May 31–June 1, 2017, Rome, Italy Lecturers Mark Wilf, PhD, Nikolay Voutchkov, PE
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