A Fundamental Study On Water Pollution Warning And Tracing Technology Based On Spectral Analysis And Fluorescence Response

At present,the problem of water pollution is still severe and the treatment of black and odorous water is facing big challenges.Part of developed regions are at the forefront of water treatment,but will be faced with the requirements to meet standards of water operation and maintenance and sectional water quality.To ensure the effectiveness of water treatment,intelligent and efficient monitoring means can monitor contaminated rivers discharge effectively.Based on multi-means intelligent sensing and detection method,to integrate advanced environment model and hardware technology,watershed monitoring and early warning system for water operation and maintenance development become the great requirements in environment and technology development in China,which also belongs to the international cutting-edge of emerging technologies and concepts such as sensing city,smart water platform and so on.This study focused on the problem of urban water pollution discharge has reached and designed a novel system including hardware,software and the monitoring network to detect water quality anomaly and identify the potential pollutant release sources on drainage system and receiving water.The basic idea is: under the three-level monitoring network,high-frequency online sensing data stream identifies water quality abnormal through time series spectrum analysis technology,at the same time,the sampling equipment retains samples automatically and then carries out parallel factor analysis(PARAFAC)and selforganizing map(SOM)clustering on the fluorescence response characteristics of pollutants,and finally locks in the industry or enterprise with pollution discharge intelligently.Two typical spectrum analysis methods,Fast Fourier Transform(FFT)and Continuous Wavelet Transform(CWT),were used to analyze the characteristics in frequency domain of high-frequency water quality time series and to develop a new method for detecting holistic abnormal quality of water based on historical baseline.Taking four typical water quality monitoring stations and their sub-basins in the Potomac River Basin of the United States as research areas,spectral analysis of two-year highfrequency online monitoring(15 min)was carried out,revealing the low-frequency periodic characteristics of water quality in river,such as day,season and year,as well as interesting high-frequency periodic changes,such as 8h、6h and 4h.Proposing a new way to identify periodic and non-periodic water quality abnormal by FFT.Based on the scale spectrum of Morlet CWT,the abnormal times,duration and range of six online water quality parameters,such as water temperature,pH,conductivity,DO,turbidity and NOxN and so on,were successfully identified.Then,15 min high-frequency rainfall data and land use data are used to identify the frequency-domain characteristics of abnormal fluctuations and to analyze the driving factors.Heavy rain events can better explain more short-term water quality abnormal,while others may be related to other pollution emissions.The intensity and frequency of water quality abnormal in areas with high degree of land development are higher than those in areas such as agriculture or forestland.There are two types of abnormity: small oscillation and large jump in frequency domain.To avoid the low fault tolerance of threshold over-standard alarm,an integrated water quality abnormal early warning method based on wavelet transform was constructed.By comparing the characteristics of historical baseline and recent fluctuation of water quality,anomaly early warning is carried out based on energy spectrum characteristics.With the support of 3-5 min of high frequency monitoring,the method can confirm the alarm within 4 h.The traceability identification of abnormal water samples can be carried out after retaining samples,and the source analysis method based on the fluorescence response characteristics of pollutants can be further studied.In this paper,a peak recognition acquaintance matching algorithm(PASM)for source selection and a new method for material analysis by PARAFAC-SOM combination method was proposed.Taking the industrial parks on both sides of the Baishakeng tributary of Maozhou River as the research area,the fluorescence response fingerprint database of pollutants was established by sampling and analysis,and the fluorescence response fingerprint database of purified chemicals was established.After testing,PASM algorithm has a high success rate(over 90%)for simple water samples.The two main components were identified through PARAFAC analysis and SOM clustering of rainwater in the park pipeline network.Making rhodamine B,acetone and salicylic acid as simulated pollutants,water distribution experiments of pure mixed samples were carried out.PARAFAC-SOM algorithm nearly identified all characteristic pollutants,but the decomposition algorithm based on fluorescence response was invalid due to fluorescence quenching.On the basis of the spectral analysis and early warning and fluorescence response traceability method,this study further designed the integrated early warning traceability equipment,including high-frequency water quality sensor module,data communication and transmission module,spectroscopic detector module,a card type master computer with fixed environmental models,a power management module and system algorithm program module,etc.With Raspberry Pi as the core controller,the prototype equipment was assembled.Experiments were carried out in laboratory simulated flume to simulate abnormal water quality events,preliminary tests of prototype equipment were completed and the tests will be further carried out in field experiment.The spectrum analysis method based on data stream makes full use of the characteristics of high frequency sensor monitoring to realize pollution early warning at a lower cost.Wet chemical analysis method is expensive,but it can provide accurate and powerful physical evidence.This study combines a variety of transdisciplinary technology with methods to provide an effective solution for pollution early warning traceability.Based on the use of environment internet framework,the establishment of river quality early warning and tracing system can assist the government in law enforcement and the daily management of responsible subjects of river operation and maintenance.