This book explores an expansive range of contemporary topics, including advanced wastewater treatment methods, solid waste management strategies, groundwater contamination modeling, and innovative monitoring of emerging pollutants. The proceedings of the 1st International Conference on Innovation and Sustainability in Civil Engineering: Shaping Tomorrow&s Infrastructure (ISCESTI-2025), held from May 14&16, 2025, at the National Institute of Technology (NIT) Patna, features a compelling volume dedicated to Environmental Engineering. This book brings together a diverse array of cutting-edge research, practical solutions, and visionary perspectives addressing critical environmental challenges through the lens of civil and environmental engineering. Groundbreaking studies presented herein utilize modern tools such as artificial intelligence, remote sensing, electrochemical processes, and bio-based technologies to enhance sustainability and efficiency in environmental systems. Key themes include prediction and risk assessment of groundwater contaminants (e.g., fluoride, arsenic, and nitrates), solid waste valorization and management, GHG emissions from municipal systems, and reuse of treated effluents. Additionally, papers investigate the environmental impact of industrial activities, nutrient recovery, and eco-material development such as biodegradable packaging and bio-toilets. A special emphasis is laid on circular economy frameworks, e-waste governance, and public health implications of pollution and micro-plastics. This book serves as an invaluable reference for researchers, environmental engineers, policy-makers, and practitioners engaged in developing sustainable and resilient environmental systems. This book underscores data-driven approaches, scalable technologies, and policy-relevant insights, aligning with global sustainability goals and the urgent need for environmentally responsible civil infrastructure.