Data Analytics Determines Co-occurrence of Odorants in Raw Water and Evaluates Drinking Water Treatment Removal Strategies

Abstract

A complex dataset with 140 sampling events was generated using triple quadrupole gas chromatography-mass spectrometer to track the occurrence of 95 odorants in raw and finished water from 98 drinking water treatment plants in 31 cities across China. Data analysis identified more than 70 odorants with concentrations ranging from not detected to thousands of ng/L. In raw water, Pearson correlation analysis determined that thioethers, non-oxygen benzene-containing compounds, and pyrazines were classes of chemicals that co-occurred, and geosmin and p(m)-cresol, as well as cyclohexanone and benzaldehyde, also co-occurred, indicating similar natural or industrial sources. Based on classification and regression tree analysis, total dissolved organic carbon and geographical location were identified as major factors affecting the occurrence of thioethers. Indoles, phenols, and thioethers were well-removed through conventional and advanced treatment processes, while some aldehydes could be generated. For other odorants, higher removal was achieved by ozonation-biological activated carbon (39.3%) compared to the conventional treatment process (14.5%). To our knowledge, this is the first study to systematically identify the major odorants in raw water and determine suitable treatment strategies to control their occurrence by applying data analytics and statistical methods to the complex dataset. These provide informative reference for odor control and water quality management in drinking water industry.

Risk Assessment for 2-MIB Odor Complaint in Drinking Water Based on Zero-Inflated Log-Normal Model

“…First, to better understand the factors influencing the 2-MIB occurrence concentrations, classification and regression trees (CART) were conducted to determine if there were underlying groupings in the 2-MIB data. CART analysis is an effective nonparametric data-mining method for the solution of classification and regression problems in an intuitive manner flexibly, which has been used for discriminant analysis of remote sensing data, environmental monitoring observations, and insect disease risk. − As described below, seasonality was found to influence 2-MIB patterns significantly. Therefore, the 2-MIB data of warm seasons (summer and autumn) and cold seasons (spring and winter) were fitted separately with zero-inflated log-normal exposure distributions to avoid amplifying or lessening risk estimates.…”

Bubbleless Air Shapes Biofilms and Facilitates Natural Organic Matter Transformation in Biological Activated Carbon

“…Engineered biofiltration, using filter media (e.g., sand, granular activated carbon (GAC)) as carriers of biofilms, is more prevalent in water treatment plants due to its higher rate of treatment (measured as substrate reduction per unit area, unit time) and thus low physical footprint. Biofiltration using GAC as a filter material, also known as the biological activated carbon (BAC) process, has been recognized as a versatile technology for achieving a high degree of removal of a variety of contaminants, such as biodegradable and recalcitrant DOM, ammonia, emerging micropollutants, and taste and odor compounds, from water. − In drinking water treatment, BAC is a potential alternative technology to conventional coagulation as a chemical-free pretreatment for ultrafiltration (UF), especially for small-scale drinking water systems . The process removes particulate matter and biopolymers (the most important organic pollutants causing membrane fouling), ensuring drinking water safety and improving the sustainability of UF .…”

Efficiency and Mechanisms of Biochar Aerogel-Assisted Biodegradation of Taste and Odor Compounds in a One-Step Membrane Bioreactor for Rural Drinking Water Production

“…Drinking water quality in rural areas is a global concern. Currently, approximately 2.2 billion people, particularly those living in remote rural areas, e.g., mountainous, pastoral, and forest areas, do not have access to safely managed or high-quality drinking water. , For example, according to a national Chinese survey, about 80% of water bodies in China have taste and odor (T&O) issues, particularly, lakes and reservoirs that serve as main water sources in rural areas . Human life depends on access to clean, safe drinking water, and consumers instinctively avoid water that tastes or smells unpleasant because this characteristic may be an indicator of a harmful supply. − The terpenes, 2-methylisobornyl/2-methylisobornol (2-MIB, C 11 H 20 O) and geosmin (GSM, trans-1,10-dimethyl-trans-9 decanol -C 12 H 22 O), originate from the metabolism and biodegradation activity of certain types of cyanobacteria, , and they have been identified in water supplies as key odorants of the musty/earthy group .…”