Harsha Ratnaweera

Harsha Ratnaweera
Norwegian University of Life Sciences (NMBU) · Faculty of Sciences and Technology (IMT)

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98
Publications
24,763
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1,126
Citations

Publications

Publications (98)
Article
Full-text available
Online monitoring of wastewater quality parameters is vital for an efficient and stable operation of wastewater treatment plants (WWTP). Several WWTPs rely on daily/weekly analysis of water samples rather than online automated wet-analyzers due to their high capital and maintenance costs. Soft-sensors are emerging as a viable alternative for real-t...
Article
Full-text available
Infiltration and inflow water (I/I-water) is a big challenge in sewage systems in many countries. I/I-water above an acceptable level indicates that the sewage system is not functioning properly. I/I-water leads to increased pumping costs and increased sewage overflow, leading to increased pollution of the receiving waters. Many rehabilitation proj...
Article
Anaerobic ammonia oxidation (anammox) is an environmentally friendly, cost-effective, and biological method for nitrogen treatment from aqueous solutions. However, slow growth rate, negative effects of high concentration of nitrite, ammonia and other pollutants (such as metals) on anammox activity are the main drawbacks of using anammox. Thus, in t...
Article
Full-text available
Landfill leachate is characterised by high chemical and biological oxygen demand and generally consists of undesirable substances such as organic and inorganic contaminants. Landfill leachate may differ depending on the content and age of landfill contents, the degradation procedure, climate and hydrological conditions. We aimed to explain the char...
Article
The study compared five NF membranes with varied water contact angles and molecular weight cut-off (MWCO) values for their effectiveness to remove dissolved organic carbon (DOC) and inorganic ions from micro-filtered water obtained from a wastewater-reclamation plant. The NF 90 membrane with the highest contact angle (79⁰, least hydrophilic) and on...
Article
Full-text available
Resource recovery from municipal wastewater has been a prime focus for a decade. Although several recovery processes already exist in the market today, the high cost of material, inherent disturbance in the influent quality, lack of real time monitoring of critical parameters, and lack of a robust automation system may result in sub-optimal perform...
Article
Full-text available
The staff of the Faculty of Chemical Technology with deep sorrow informs about the death of the dean of the faculty Astrelin Igor Mikhailovich - creative, talented person, brilliant teacher, an outstanding scientist, a caring husband and father. Igor Mikhailovich passed away on October 23, 2020 at the age of 79 after a serious illness.
Conference Paper
Full-text available
Wastewater from industries are mostly treated by anaerobic treatment which is more benefit due to the high efficiency of removal of pollutant with greater concentration comparing to aerobic treatment. Anaerobic treatment performance is antagonistically influenced by slight pH value changing, especially for methanogenesis bacteria. Chemical Oxygen D...
Article
Full-text available
The Municipality of Asker (Norway) is at risk of not meeting the water quality targets set by the European Union Water Framework Directive within the stipulated timeframe. While there are multiple factors negatively impacting water quality in the municipality, wastewater is likely to be a major contributor. Infiltration and inflow water (I/I-water)...
Article
Full-text available
Enhanced biological phosphorus removal (EBPR) from municipal wastewater has been achieved in a multistage Moving Bed Biofilm Reactor (MBBR) configuration. The process operations can be further optimized by real-time monitoring of water quality parameters in the individual chambers of the EBPR-MBBR process. This work presents a hybrid, soft-sensor a...
Article
Model-based soft sensors can enhance online monitoring in wastewater treatment processes. These soft sensor scripts are executed either locally on a programmable logic controller (PLC) or remotely on a system with data-access over the internet. This work presents a cost-effective, flexible, open source IoT solution for remote deployment of soft sen...
Conference Paper
Full-text available
According to the WHO and UNICEF, 71% of the world's population used a safely managed drinking water service (SDG indicator 6.1.1) in 2017. It is to a great extent due to an effective disinfection inactivating pathogenic microorganisms during water treatment and preventing their regrowth in water distribution systems. Many common disinfectants such...
Book
Water supply and water management services are among the most critical infrastructures in society, providing safe and affordable drinking water, managing wastewater to avoid floods and environmental pollution, and enabling the reuse and replenishment of scarce water resources. With water and wastewater facilities and infrastructure intrinsic to our...
Article
Full-text available
Positive effects of retrofitting MBBR and IFAS systems into MBRs can be exploited by introducing chemical enhancement applying coagulants in the membrane separation step. The current study reports basic principles of chemical enhancement with aluminium sulphate coagulant in biofilm-MBR (Bf-MBR) based on results of total recycle tests performed at d...
Article
Full-text available
Online monitoring of water quality parameters can provide better control over various operations in wastewater treatment plants. However, a lack of physical online sensors, the high price of the available online water-quality analyzers, and the need for regular maintenance and calibration prevent frequent use of online monitoring. Soft-sensors are...
Conference Paper
Full-text available
This work presents experimental proof of concept of membrane flux enhancement in biofilm ceramic membrane bioreactor applying poly-and monomeric inorganic coagulants as membrane fouling reducers, achieving maximum flux improvements by using polyaluminum chlorides. Mathematical models based on results of Total Recycle Tests with four coagulants demo...
Article
Full-text available
The membrane bioreactor (MBR) and the biofilm membrane bioreactor (BF-MBR) are among key solutions to water scarcity; however, membrane fouling is the major bottleneck for any expansion of these technologies. Prepolymerized aluminum coagulants tend to exhibit the greatest extent of fouling alleviation, with the reduction of soluble microbial produc...
Article
In wastewater treatment plants, the most adopted sensors are those with the properties of low cost and fast response. Soft sensors are alternative solutions to the hardware sensor for online monitoring of hard-to-measure variables, such as chemical oxygen demand (COD) and total phosphorus (TP). The purpose of this study is to obtain a modelling app...
Article
Full-text available
Considering new legislative and economic restrictions caused by the water crisis, this work focuses on a more efficient wastewater treatment process, which combines biological treatment in a moving bed biofilm system with a membrane bioreactor (BF-MBR) and coagulation, particularly addressing fouling alleviation in the separation stage. The study j...
Article
Full-text available
Municipal wastewater sludge was produced by chemical coagulation of synthetic wastewater (sww) based on Synthene Scarlet P3GL disperse dye and real municipal wastewater (nww), coagulated by commercial coagulants PAX (prepolymerised aluminum coagulant) and PIX (a ferric coagulant based on Fe2(SO4)3). An attempt was made to correlate the sludge’s dew...
Article
Full-text available
Infiltration and inflow of non-sewer water to the wastewater network (I/I-water) may have a number of both financial and environmental consequences. In Norway, there are two commonly used methods for calculating the volume of I/I-water, The Dilution method (DM) and the Water Balance Method (WBM). When comparing the methods, the WBM gives a lower va...
Preprint
Full-text available
Exploiting capacity of sewer system using decentralized control is a cost-effective mean of minimizing the overflow. Given the size of the real sewer system, exploiting all the installed control structures in the sewer pipes can be challenging. This paper presents a ‘divide and conquer’ solution to implement decentralized control measures based on...
Preprint
Full-text available
Combined Sewer Overflow (CSO) is a major problem to be addressed by many cities. Understanding the behavior of sewer system through proper urban hydrological models is an effective method of enhancing sewer system management. Conventional deterministic methods, which heavily rely on physical principles, is inappropriate for real-time purpose due to...
Preprint
Full-text available
This paper presents a novel Inter Catchment Wastewater Transfer (ICWT) method for mitigating sewer overflow. The ICWT aims at balancing the spatial mismatch of sewer flow and treatment capacity of Wastewater Treatment Plant (WWTP), through collaborative operation of sewer system facilities. Using a hydraulic model, the effectiveness of ICWT is inve...
Article
Full-text available
Even though the Northern part of Sri Lanka is dry zone, it has potential water resources by the means of constructed tanks and diversion along the river basins. But some part of this region still frequently suffering many water related issues and water scarcity, not only in the domestic usage but also for demand for agriculture. Meanwhile, ineffici...
Article
Full-text available
Membrane fouling highly limits the development of Membrane bioreactor technology (MBR), which is among the key solutions to water scarcity. The current study deals with the determination of the fouling propensity of filtered biomass in a pilot-scale biofilm membrane bioreactor to enable the prediction of fouling intensity. The system was designed t...
Article
Online instruments are widely used in wastewater treatment plants and drinking water treatment plants for process monitor and control. Although maintenances of online sensors are important routine works, potential measurement errors of online sensors are challenging not only monitoring of coagulation process but also the coagulant dosage control sy...
Article
Full-text available
Membrane bioreactor (MBR) is a progressive alternative to conventional waste-water treatment. However, membrane fouling is one of the most significant barriers to further development of the MBR technology since it has a detrimental effect on system performance and stability. Therefore, a number of studies have been developed to comprehend the fouli...
Article
Microbial community diversity determines the function of each chamber of multi-stage moving bed biofilm reactor (MBBR) systems. How the microbial community data can be further used to serve wastewater treatment process modelling and optimization has been rarely studied. In this study, a MBBR system was set up to investigate the microbial community...
Article
Full-text available
This paper described manage sewer in-line storage control for the city of Drammen, Norway. The purpose of the control is to use the free space of the pipes to reduce overflow at the wastewater treatment plant (WWTP). This study combined the powerful sides of the hydraulic model and neural networks. A detailed hydraulic model was developed to identi...
Article
Full-text available
The novel automatic flow system, direct-injection detector (DID) integrated with multi-pumping flow system (MPFS), dedicated for the photometric determination of orthophosphates in wastewater and freshwater samples is for the first time described. All reagents and the sample were injected simultaneously, in counter-current into the reaction-detecti...
Article
Settleability of activated sludge is one of the most common problems that restricts the efficiency of activated sludge system. Obvious seasonal variation of settleability was found in the activated sludge system of a full scale wastewater treatment plant (WWTP) during 2 years of observation. Principal component analysis (PCA) was applied to study t...
Article
Full-text available
A novel floc sensor prototype was tested in a Norwegian municipal wastewater treatment plant. The resulting images of flocs, captured using a specially designed software, were analysed by texture image analysis technique—grey level co-occurrence matrix (GLCM). The results of image analysis were merged with the coagulation process measurement data—i...
Article
This review examines the potential of spectroscopic methods in online and real time water quality monitoring. Extensive research has shown that measurements of changes of absorbance and fluorescence of wastewater and drinking water during its treatment are predictive of the reduction of levels of trace-level organic contaminants (TrOC) or pathogens...
Article
Combined sewer overflow causes severe water pollution, urban flooding and reduced treatment plant efficiency. Understanding the behavior of CSO structures is vital for urban flooding prevention and overflow control. Neural networks have been extensively applied in water resource related fields. In this study, we collect data from an Internet of Thi...
Article
Sewer overflow is a priority concern for many cities. Owing to the high density of buildings and populations, constructing new storage tanks in urban areas is getting more and more difficult. Therefore, this paper proposes a novel Inter Catchment Wastewater Transfer (ICWT) method for sewer overflow mitigation. The ICWT method aims at redistributing...
Article
Full-text available
Monitoring of effluent turbidity is essential to evaluate the coagulation process in wastewater treatment plants (WWTPs). A digital imaging system based on the texture analysis of flocs has been tested in a Norwegian municipal WWTP to predict changes in coagulation conditions and outlet turbidity. Principal component analysis (PCA) was applied to p...
Article
Arsenic is one of the most dangerous inorganic pollutants present in drinking water, which is released both from certain human activities and naturally from the Earth's crust. Arsenic is usually present in water in two oxidation states, as arsenite (As(III)) or arsenate (As(V)). Arsenate is usually easier to remove than arsenite. Therefore, the goa...
Poster
Full-text available
This poster presents the idea of MPC control of nitrate concentration in a pre-denitrification system, using time series artificial neural network model.
Poster
The on-line monitoring of chemical oxygen demand (COD) and total phosphorus (TP) limits wastewater treatment plants (WWTPs) to achieve better control of aeration and chemical dosing, because COD and TP require longer time to measure and are too expensive to measure online. In this study, we use statistical methods to predict COD and TP based on the...
Article
The daily, weekly and seasonal variation of influent characteristics of wastewater treatment plants (WWTPs) highly affects the performance of wastewater treatment. In cold climate area, snow melting happens frequently in cold season and affects wastewater characteristics significantly. The dilution effect of snow melting in cold season makes it imp...
Article
Physical online sensors are widely used in wastewater treatment plants. The high costs of acquisition and maintenance as well as the delayed response due to long hydraulic retention times, applications of some physical online sensors are limited. Consequently, studies on developing software sensors have been drawn much attentions these years. Aimin...
Article
The on-line monitoring of Chemical oxygen demand (COD) and total phosphorus (TP) restrains wastewater treatment plants to achieve better control of aeration and chemical dosing. In this study, we applied principal components analysis (PCA) to find out significant variables for COD and TP prediction. Multiple regression method applied the variables...
Article
Full-text available
The Jaffna Peninsula lie in the northern-most part of Sri Lanka. It is separated from the mainland by two external lagoons. The Jaffna Peninsula depends for its water on the rainfall which percolates and stored in lime stone aquifers. The average annual rainfall is 1284 mm/year and the potential vapour transpiration is 1858.8 mm. The Jaffna Peninsu...
Article
Full-text available
The required coagulant dosage is strongly related to the quality of raw water or wastewater. Online sensors for most quality parameters are now readily available to treatment facilities, yet remain rarely used in treatment process control. This paper presents the evaluation of an advanced coagulant dosing control system based on online measurements...
Article
Full-text available
In this study, a pilot test of electrocoagulation (EC with aluminium electrodes) of natural municipal wastewater was performed. In view of the obtained results and the unique and innovative nature of the proposed procedures and solutions, EC can be regarded not only as a preliminary purification step, but also as a comprehensive alternative to othe...
Conference Paper
Unit hydrograph and sediment-graph is very important for an evaluation of flood runoff and dead storage of impoundment in ungauged basin. The objective of this research is to develop a synthetic unit hydrograph (UH) and sediment-graph (SG) based on Geographic Information System (GIS). Mooloya catchment, Sri Lanka, having an area of 19.29 km2 was se...
Article
Full-text available
Volumetric diameters Dv and specific surface area SpS of sludge particles formed during chemical coagulation and electrocoagulation of sewage were determined. The obtained aggregate-flocs differed substantially in both Dv and SpS values. The differences in Dv and SpS values of the analyzed particles were interpreted based on theoretical models for...
Article
Full-text available
Phosphates are becoming a limited resource as mineral phosphorus (P) reserves are dropping down and probably will be over within next three to five decades. One of the solutions for this problem is to reuse the wastewater sludge as the P source in plant growth. However, the potential to increase the plant availability of phosphorus (PAP) in coagula...
Article
Full-text available
Flocs formation and growth are important characteristics in wastewater coagulation process. The shape and size of flocs highly affect further separation processes, therefore resulting treatment efficiency of wastewater after coagulation. Observed images of flocs tend to show strong relations to coagulation parameters: dose and coagulation time. In...
Conference Paper
The performance of six wastewater treatment plants, were evaluated in the cold climate of Norway. Many wastewater treatment plants in Norway were built in the 1970s and 1980s, due to effect of climate change in cold climate area of Norway, most of these treatment plants are confronting re-build or expand. Besides surface load, the performance of WW...
Conference Paper
The present particle separation studies mainly focus on particle removal in the wastewater treatment plant, however, the influence of sewer systems on particle separation is also critical. An ongoing project in Drammen, Norway is studying optimisation of particle separation and sewer systems with intelligent instruments and technologies rather than...
Conference Paper
The required coagulant dosage is strongly related to the quality of raw water or wastewater. Online sensors for most quality parameters are now readily available to treatment facilities, yet remain rarely used in treatment process control. This paper presents the evaluation of an advanced coagulant dosing control system based on online measurements...
Conference Paper
Activated sludge settleability variate seasonally in full-scale wastewater treatment plant (WWTP) during two years observation. Principal component analysis (PCA) was applied to study the correlation of 19 disturbances and sludge volume index (SVI). As a result, four influent disturbances (BOD/COD, COD/phosphorus, COD/nitrogen ratio and Chloride) w...
Article
Coagulant dosing control in drinking and wastewater treatment plants (WWTPs) is often limited to flow proportional concepts. The advanced multi-parameter-based dosing control systems have significantly reduced coagulant consumption and improved outlet qualities. Due to the long retention time in separation stages, these models are mostly based on f...
Article
Full-text available
Coagulation-flocculation process is one of the most commonly used treatment process in water and wastewater treatment. Particles (PA) and phosphates (P) removal are the main objectives in wastewater coagulation. There is a general agreement on the dominant mechanism of PA and P removal during coagulation. While it is agreed that the PA and P remova...
Article
Full-text available
Phosphates are becoming a limited resource as mineral phosphorus (P) reserves are dropping down and probably will be over within next three to five decades. One of the solutions for this problem is to reuse the wastewater sludge as the P source in plant growth. However, the potential to increase the plant availability of phosphorus (PAP) in coagula...
Article
Volumetric parameters Dv and specific surface area sps of sludge aggregates-flocs formed during chemical coagulation and electrocoagulation of synthetic wastewater were determined. The obtained aggregates-flocs differed significantly in Dv and sps values. The differences in the Dv and sps values of the analysed particles were interpreted based on t...
Article
Full-text available
Abstracts Household wastewater is originated from common peoplès activities and has a potential harmful impact on the environment if discharged directly without a proper treatment. Toilet wastewater or black water (BW) contains urine, faeces, toilet paper and flushing water and it contains the majority of pollutants obtained from a single household...
Article
Full-text available
Coagulation is an essential process for the removal of suspended and colloidal material from water and wastewater. However, no comprehensive or universally accepted mathematical description of the process has been developed so far. Therefore, process optimization and control is usually based on data from jar tests and simple flow-proportional dosin...
Article
Full-text available
The structure of sludge is closely associated with the process of wastewater treatment. Synthetic dyestuff wastewater and sewage were coagulated using the PAX and PIX methods, and electro-coagulated on aluminium electrodes. The processes of wastewater treatment were supported with an organic polymer. The images of surface structures of the investig...
Chapter
Full-text available
Abstract Composite adsorbents based on zirconium oxyhydroxide (ZOH) with adding of Al2O3, Fe2O3 and Mn3O4 were synthesized by a sol-gel method to remove of As(V) and As(III) from drinking water. The characterization of adsorbents and their adsorption behavior are investigated. Due to the high specific surface area, from 355 to 541 m2/g and the pres...
Conference Paper
Full-text available
Phosphates are becoming a limited resource as mineral Phosphorus (P) reserves are dropping down and probably will be over within next 3-5 decades. One of the solutions for this problem is to reuse the wastewater sludge as the P source in plant growth. However, the potential to increase the plant availability of phosphates (PAP) in coagulated sludge...