Operational challenges of industrial wastewater treatment plants in a multi-river province of China: implications for problem identification and management.

INTRODUCTION

Industrial wastewater treatment plants are the primary sources of pollution in receiving water bodies, and their operational status directly affects the river water quality security, especially in provinces with multiple rivers. However, most reports focus on individual case studies and fail to conduct systematic research across basin and regional scales to support water environment risk assessment and control for decision-making and administrators.

METHODS

Given this, this study aimed to sort out the operational problems of industrial WWTPs and corresponding countermeasures at both basin and provincial scales, based on a 3-year investigation conducted in Gansu Province.

RESULTS

A comprehensive profile of operational problems, involving three common and 15 specific aspects, was developed at both basin and provincial scales. At the provincial scale, operational problems of WWTPs mainly included high dependence treatment rate (50.0%), low-load operation in terms of influent quantity (47.4%) and quality (e.g., chemical oxygen demand: 41.7%), a high proportion of WWTPs with a compliance rate below 90% (34.4%), high unit sludge yield (2.02 t/104 m3), and high operational costs (3.91 CNY/m3). Major operational problems of WWTPs varied across the three basins. For example, design- and influence-related problems were more prominent in the Yellow River basin, whereas influentrelated and actual-operational performance problems were more prevalent in the Northwest River basin. Low loads of influent quantity and quality were the primary factors influencing the operational performance of WWTPs, followed by the operational level and design. These results suggest that for enhancing the operational efficiency of industrial WWTPs, three important steps are required to be implemented: (i) optimizing operational performance, (ii) increasing influent loads in terms of quantity and quality, and (iii) addressing design deficiencies.

DISCUSSION: Collectively, these measures can facilitate a shift from an effluent compliance-oriented approach to comprehensive process-based optimization and management. This study also provides a useful framework for investigating industrial WWTPs and identifying and addressing operational challenges.