Anaerobic Treatment of Domestic Wastewater (Present Status and Potentialities)

In many semiarid and arid countries, water is now becoming an increasingly limited resource and managers are forced to take into account sources of water that may be used economically and efficiently to encourage further development. Simultaneously, with the population increasing at a high rate, the requirement for increased production of food is apparent. The prospective for irrigation to increase both the agricultural productivity and living standards of the poor has long been acknowledged. Irrigated agriculture occupies nearly 17% of the total arable land in the world but the yield from this land includes about 34% of the world total. This perspective is even more distinct in arid areas like the Near East Region, where only 30% of the cultivated land is irrigated but it yields around 75% of total agricultural production. In the same area, more than 50% of the food necessities are imported and the increased rate in demand for the food surpasses the rate of an upsurge in agricultural production (Tunney et al., 2000).

Hybrid processes combining activated carbon and nanofiltration have been studied to identify the optimum solution for advanced wastewater treatment in high quality water reclamation and reuse. With a focus on the removal of bulk and trace organic compounds the investigation identified three promising process combinations, namely powdered activated carbon followed by nanofiltration (PAC/NF), granular activated carbon followed by nanofiltration (GAC/NF) and nanofiltration followed by granular activated carbon (NF/GAC). The removal potential was examined in lab and pilot scale for a range of refractory pharmaceuticals and industrial chemicals typically detected in effluent in trace concentrations ranging from ng/L to μg/L. Fluorescence excitation emission spectroscopy was employed for the investigation of the fate of effluent organic matter. The optimum strategies for operation of the hybrid processes were determined in pilot scale. The experiments were conducted at the Wastewater Treatment Plant Aachen Soers providing an effluent of high quality with low dissolved organic carbon (DOC) concentrations of about 5 mg/L.

Abstract Wastewater treatment plants (WWTPs) are scrutinized by Environmental Authorities particularly regarding the compliance to discharge limit values fixed by national and local regulations. An integrated approach is necessary to achieve the objectives established with Directive 2000/60/EC (WFD) considering the ecological status of the receiving water body and the quality of the discharge. Specifically, documentary, technical, management and analytical controls should be developed. Moreover, integrative information on the behaviour of the activated sludge in the aeration tank can be useful for plant managers as well as for the regulating Authorities. The study presents the experience concerning WWTP regulation considering the analytic assessment of the discharge as well the monitoring of the Sludge Biotic Index (SBI) for activated sludge. Data from monitoring during the period 2008–14 on SBI values and chemical and microbiological data on the discharges of a sample of 35 WWTPs in the province of Venice (north-east Italy, Veneto region) are presented and discussed. Together with chemical and microbiological analysis, the SBI appears to be a highly useful index for the integrative assessment of plant functionality, in particular when monitoring and identifying critical situations that can determine the exceedance of discharge limit values. The SBI method, in an integrated control approach, can be used for small and medium sized WWTPs that only treat domestic wastewaters. In a case by case assessment this may even substitute part of the analytical monitoring carried out in the WWTPs' control process.

This book provides an overview of the most studied AOPs, some of which are largely implemented for water remediation. The fundamental principles, kinetic modeling, water quality impact on process performance, byproduct formation, economics, examples of research and pilot studies, full-scale applications and future research needs are discussed for each advanced oxidation process.