scholarly journals In situ continuous monitoring of nitrogen with ion-selective electrodes in a constructed wetland receiving treated wastewater: an operating protocol to obtain reliable data

2018 ◽  
Vol 77 (6) ◽  
pp. 1706-1713 ◽  
Author(s):  
Sandrine Papias ◽  
Matthieu Masson ◽  
Sébastien Pelletant ◽  
Stéphanie Prost-Boucle ◽  
Catherine Boutin
Keyword(s):  
Continuous Monitoring ◽  
Wastewater Treatment Plants ◽  
Treated Wastewater ◽  
Ion Selective Electrodes ◽  
Calibration Data ◽  
Effluent Quality ◽  
Evaluation Of Performance ◽  
Real Performance

Abstract Constructed wetlands receiving treated wastewater (CWtw) are placed between wastewater treatment plants and receiving water bodies, under the perception that they increase water quality. A better understanding of the CWtw functioning is required to evaluate their real performance. To achieve this, in situ continuous monitoring of nitrate and ammonium concentrations with ion-selective electrodes (ISEs) can provide valuable information. However, this measurement needs precautions to be taken to produce good data quality, especially in areas with high effluent quality requirements. In order to study the functioning of a CWtw instrumented with six ISE probes, we have developed an appropriate methodology for probe management and data processing. It is based on an evaluation of performance in the laboratory and an adapted field protocol for calibration, data treatment and validation. The result is an operating protocol concerning an acceptable cleaning frequency of 2 weeks, a complementary calibration using CWtw water, a drift evaluation and the determination of limits of quantification (1 mgN/L for ammonium and 0.5 mgN/L for nitrate). An example of a 9-month validated dataset confirms that it is fundamental to include the technical limitations of the measuring equipment and set appropriate maintenance and calibration methodologies in order to ensure an accurate interpretation of data.

New ORP/pH based control strategy for chlorination and dechlorination of wastewater: pilot scale application

2006 ◽  
Vol 53 (6) ◽  
pp. 145-151 ◽  
Author(s):  
H. Kim ◽  
S. Kwon ◽  
S. Han ◽  
M. Yu ◽  
J. Kim ◽  
...  
Keyword(s):  
Wastewater Treatment Plants ◽  
Pilot Scale ◽  
Reducing Agents ◽  
Free Chlorine ◽  
Treated Wastewater ◽  
Aquatic Life ◽  
Complete Inactivation ◽  
Excess Amount ◽  
Chlorine Demand

Due to its efficiency and low capital demands, chlorination has been widely used for disinfection in many wastewater treatment plants. Since the oxidation power of free chlorine is bigger than combined chlorines which are formed from the reaction between chlorine and reducing agents in water (especially, NH4+ and organic nitrogen), for effective disinfection, excess amount of chlorine is added until all the reducing agents are oxidized and free chlorine is available. After chlorination, chlorine residues in wastewater are usually reduced with SO2 or sulfites before the treated wastewater is discharged, since they are toxic to aquatic life. Addition of excess amount of SO2 or sulfite should be avoided. Otherwise, they consume dissolved oxygen in a river or stream and may have adverse impact on the aquatic life. Determination of wastewater chlorine demand and of sulfite dosages for dechlorination has been a challenge to WWTP operators, due to the dynamic characteristics of wastewater. Recently, a new ORP/pH based approach to determine chlorine demand and sulfite dosage was proposed. The method utilizes significant points occurring on the pH and ORP profiles during chlorination and dechlorination titrations. In this study, the proposed automatic titration system has been implemented into a control system to optimize chlorine and sulfite doses for a pilot scale chlorination/dechlorination system. In short, the disinfection system with the pH/ORP based controller showed very successful results; complete inactivation of total coliforms, and almost zero residual chlorines and high DO in its effluent.

scholarly journals Sediment Transport in Sewage Pressure Pipes, Part I: Continuous Determination of Settling and Erosion Characteristics by In-Situ TSS Monitoring Inside a Pressure Pipe in Northern Germany

Water ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 2125 ◽  
Author(s):  
Martin Rinas ◽  
Jens Tränckner ◽  
Thilo Koegst
Keyword(s):  
Sediment Transport ◽  
Sensor Data ◽  
Urban Region ◽  
Calibration Data ◽  
Northern Germany ◽  
Erosion Behavior ◽  
Pressure Pipe ◽  
One Year

Continuous measurement systems are widely spread in sewers, especially in non-pressure systems. Due to its relatively low costs, turbidity sensors are often used as a surrogate for other indicators (solids, heavy metals, organic compounds). However, little effort is spent to turbidity sensors in pressurized systems so far. This work presents the results of one year in-situ turbidity/total suspended solids (TSS) monitoring inside a pressure pipe (600 mm diameter) in an urban region in northern Germany. The high-resolution sensor data (5 s interval) are used for the determination of solids sedimentation (within pump pauses) and erosion behavior (within pump sequences). In-situ results from sensor measurements are similar to laboratory results presented in previous studies. TSS is decreasing exponentially in pump pauses under dry weather inflow with an average of 0.23 mg/(L s). During pump sequences, solids eroded completely at a bed shear stress of 0.5 N/m². Sedimentation and erosion behavior changes with the inflow rate. Solids settle faster with increasing inflow: at storm water inflow with an average of 0.9 mg/(L s) and at diurnal inflow variation up to 0.6 mg/(L s) at 12:00 a.m. The results are used as calibration data for a sediment transport simulation in Part II.

scholarly journals LISÍMETROS DE PESAGEM PARA MEDIDAS DE EVAPOTRANSPIRAÇÃO EM ESTUFA

Irriga ◽  
2017 ◽  
Vol 22 (4) ◽  
pp. 715-722
Author(s):  
Izabela Paiva Martins ◽  
Rogério Teixeira De Faria ◽  
Luiz Fabiano Palaretti ◽  
Alexandre Barcellos Dalri ◽  
Carolina Oliverio ◽  
...  
Keyword(s):  
Water Balance ◽  
Storage System ◽  
Absolute Error ◽  
Load Cell ◽  
Calibration Data ◽  
Mass Variation ◽  
Water Balance Components ◽  
E Mail

LISÍMETROS DE PESAGEM PARA MEDIDAS DE EVAPOTRANSPIRAÇÃO EM ESTUFA  IZABELA PAIVA MARTINS; ROGÉRIO TEIXEIRA DE FARIA; LUIZ FABIANO PALARETTI; ALEXANDRE BARCELLOS DALRI; CAROLINA OLIVERIO E LUIS GUILHERME POLIZEL LIBARDI Departamento de Engenharia Rural, Universidade Estadual Paulista - Campus Jaboticabal, Via de Acesso Professor Paulo Donato Castelane, Vila Industrial, Jaboticabal, Sp, Brasil. E-mail: [email protected], [email protected], [email protected], [email protected], [email protected], [email protected].   1 RESUMO Lisímetros de pesagem são utilizados com a finalidade de determinar os componentes do balanço hídrico, particularmente a evapotranspiração e a evaporação. Dentre as inúmeras metodologias, esta apresenta maior precisão, porém, para a obtenção de dados confiáveis, sua calibração deve ser executada in situ. Esse trabalho objetivou calibrar 12 lisímetros de pesagem, verificar a presença de linearidade e histerese das medidas, e avaliar a precisão dos equipamentos. Os lisímetros apresentavam diâmetro e profundidade de 30 cm, com uma célula de carga em cada lisímetro para a determinação da variação de massa, acoplada a um sistema de aquisição e armazenamento de dados. A calibração foi realizada comparando-se a adição e remoção de pesos com massa conhecida (em kg) com a leitura da célula de carga (em mV). Os dados de calibração foram lineares, apresentando correlação significativa da massa em resposta a voltagem. Os coeficientes angular e linear variaram de 762,78 a 1187,8 kg mV-1 e -444,99 a -798,00 kg, respectivamente. O erro absoluto variou de 0,03 a 0,54, mostrando alta precisão dos lisímetros. A precisão constatada na obtenção da variação da massa foi de 0,79 mm, com o índice de concordância de Willmott foi de 0,99, mostrando a concordância entre os valores estimados e os observados. Conclui-se que os lisímetros são adequados para a determinação da evapotranspiração de cultivo. Palavras-chave: lisimetria, célula de carga, balanço hídrico  MARTINS, I. P.; FARIA, R. T. de; PALARETTI, L. F.; DALRI, A. B.; OLIVERIO, C.; LIBARDI, L. G. P.WEIGHING LYSIMETERS FOR GREENHOUSE EVAPOTRASPIRATION MEASUREMENTS  2 ABSTRACT Weighing lysimeters are used for the purpose of determining water balance components, especially for evapotranspiration and evaporation. Within all know methods, lysimeter is considered the most accurate, but in order to obtain reliable data, their calibration must be performed in situ. The objective of this work was to calibrate 12 lysimeters to verify measurements’ linearity and the existence of hysteresis, besides evaluating the equipment's accuracy. The lysimeters had diameter and depth of 30 cm, with one load cell in each lysimeter for determination of mass variation,  connected to a data acquisition and storage system. The calibration was performed by comparing the load and unload know mass (kg) with the load cell reading (mV). The calibration data were linear, presenting a significant mass correlation in response to voltage. The angular and linear coefficients varied from 762.78 to 1187.8 kg mV-1 and -499.99 to -798.00 kg, respectively. The absolute error ranged from 0.03 to 0.54, showing a high accuracy of the lysimeters. The accuracy for mass variation was 0.79 mm and the Willmott concordance index was 0.99, showing the good agreement between the estimated and observed values. It can be concluded that lysimeters are suitable for crop evapotranspiration determination. Keywords: lisimetry, load cell, water balance 

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