Analysing Pan Evaporation to Understand Wastewater Treatment Plant Performance, A Case Study in A Manufacturing Industry

Ridwan Muhamad Rifai, Fikri Iqbal Rahmadhani, Endro Hargi Saputro, Mega Septia Sarda Dewi, Aswin Pasaribu


Water loss has become a problem with the balance of a water system, including one in the industry. General opinion has considered evaporation as one of the main justifications for explaining the water loss, especially in the area with a higher daily temperature. A study was conducted on a wastewater treatment system owned by a manufacturing industry consisting of semi-open-air sedimentation and aeration ponds, which suddenly experienced a significant deficit in its water balance. Problem-solving was performed by 8-Step Problem Solving approach and root causes were confirmed by estimating water evaporation. The actual water evaporation rate (E) was approached by pan evaporation (Epan) using the partial pressure of the water vapour and the pan evaporation coefficient (Kpan). The study revealed that evaporation (1.67±0.59mm.d-1 and 1.72±0.62mm.d-1, for sedimentation pond and aeration pond, respectively) was not the main cause of sudden significant water loss  (R2 = .490, p-value < .05) and confirmed another root cause. In parallel, a water balance model was constructed and fitted the actual condition (R = .987). A countermeasure was performed against the confirmed root cause followed by a monthly evaluation of water loss using the constructed model with a 3σ threshold value (UCL = 9.55%) which showed the elimination of the problem.


evaporation; problem-solving; water balance; wastewater; WWTP modelling

Full Text:



Ahmad, T., Ahmad, K., Alam, M. (2017) Sludge quantification at water treatment plant and its management scenario, Environ Monit Assess 189, 453.

Al-Washali, T.M., Sharma, S.K., Kennedy, M.D. (2018) Alternative Method for Nonrevenue Water Component Assessment, J Water Resour Plan Manag 144.

Asdrubali, F. (2009) A scale model to evaluate water evaporation from indoor swimming pools, Energy Build 41, 311–319.

Delclaux, F., Coudrain, A., Condom, T. (2007) Evaporation estimation on Lake Titicaca: a synthesis review and modelling, Hydrol Process 21, 1664–1677.

Deng, X.N., Cui, Y.B., Gao, W., Chen, R. (2015) Characteristics of Sludge Moisture Content Variation in Sludge Drying Reed Beds, Applied Mechanics and Materials 768, 515–519.

Izady, A., Abdalla, O., Sadeghi, M., Majidi, M., Karimi, A., Chen, M. (2016) A Novel Approach to Modeling Wastewater Evaporation Based on Dimensional Analysis, Water Resources Management 30, 2801–2814.

Jensen, M.E. (2010) Estimating evaporation from water surfaces, in CSU/ARS Evapotranspiration Workshop, Fort Collins, 15 March 2010.

Judd, S. (2019) Watermaths Process Fundamentals for the Design and Operation of Water and Wastewater Treatment Technologies, IWA Publishing, London.

Khater, V., Fouad, H., El-Magd, A., Hassanain, A. (2016) Effect of Pipe Material and Size on Water Losses at Different Networks in Egypt, Archives of Current Research International 5, 1–12.

Martínez-Granados, D., Maestre-Valero, J.F., Calatrava, J., Martínez-Alvarez, V. (2011) The Economic Impact of Water Evaporation Losses from Water Reservoirs in the Segura Basin, SE Spain, Water Resources Management 25, 3153–3175.

Mathioudakis, V.L., Kapagiannidis, A.G., Athanasoulia, E., Diamantis, V.I., Melidis, P., Aivasidis, A. (2009) Extended Dewatering of Sewage Sludge in Solar Drying Plants, Desalination 248, 733–739.

Merck & Co. (2019) 8-Step Problem Solving Methodology Training-Participant Guide, MPS Development, Merck & Co., New Jersey.

Mesquita, J.B. de F., Lima Neto, I.E., Raabe, A., de Araújo, J.C. (2020) The influence of hydroclimatic conditions and water quality on evaporation rates of a tropical lake, J Hydrol (Amst) 590, 125456.

Murray, F.W. (1967) On the Computation of Saturation Vapor Pressure, Journal of Applied Meteorology 6, 203–204.<0203:OTCOSV>2.0.CO;2

Obianyo, J., Agunwamba, J. (2015) Modeling of Evaporation Losses in Sewage Sludge Drying Bed, Nigerian Journal of Technology 34, 890.

Roderick, M.L., Rotstayn, L.D., Farquhar, G.D., Hobbins, M.T. (2007) On the attribution of changing pan evaporation, Geophys Res Lett 34, L17403.

Smith, C.C., Löf, G., Jones, R. (1994) Measurement and analysis of evaporation from an inactive outdoor swimming pool, Solar Energy 53, 3–7.

Turza, R., Füri, B.B. (2017) Experimental Measurements of the Water Evaporation Rate of a Physical Model, Slovak Journal of Civil Engineering 25, 19–23.

Wang, K., Liu, X., Li, Y., Yang, X., Bai, P., Liu, C., Chen, F. (2019) Deriving a long-term pan evaporation reanalysis dataset for two Chinese pan types, J Hydrol (Amst) 579, 124162.

Webb, E.K. (1966) A pan-lake evaporation relationship, J Hydrol (Amst) 4, 1–11.


Article Metrics

Abstract view : 0 times
PDF - 0 times


  • There are currently no refbacks.

Copyright (c) 2023 Ridwan Muhamad Rifai, Fikri Iqbal Rahmadhani, Endro Hargi Saputro, Mega Septia Sarda Dewi, Aswin Pasaribu

Creative Commons License
This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.


Jurusan Teknik Kimia Universitas Syiah Kuala, Jl. Tgk. Syech Abdur Rauf No.7, Kopelma Darussalam, Banda Aceh, INDONESIA



Nasrul Arahman, Prof. Dr. S.T., M.T.
Phone: +62813-6092-7917



Mirna Rahmah Lubis
Wahyu Rinaldi, ST, M.Sc.