Tham khảo tài liệu 'wiley wastewater quality monitoring and treatment_16', khoa học tự nhiên, công nghệ môi trường phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Characteristics and Impact of Wastewater Discharges III The impact of a wastewater discharge in a receiving medium depends generally on several factors adapted from US EPA 1 quantities composition and potential bioaccumulation or persistence of the pollutants to be discharged 2 potential transformation including degradation and transport of the pollutants and their by products by biological physical or chemical processes 3 composition and vulnerability of potentially exposed biological communities 4 importance of the receiving water area to the surrounding biological community . spawning sites migratory pathways 5 potential direct or indirect impacts on human health 6 existing or potential recreational and commercial fishing. Among the potential impacts on receiving medium some pollutants like ammonia nitrate phosphate and emerging pollutants have to be highlighted. The ecological impact of ammonia in aquatic ecosystems is on the one hand acute toxicity depending on concentration and pH see Chapter and on the other hand chronic toxicity regarding fishes and benthic invertebrate populations reduced reproductive capacity and growth of young Environment-Canada 2001 . The zone of impact varies greatly with discharge conditions river flow rate temperature and pH. Under estimated average conditions some municipal wastewater discharges could be harmful for 10-20 km Environment-Canada 2001 . Severe disruption of the benthic flora and fauna has been noted below municipal wastewater discharges. Recovery may not occur for many 20-100 kilometres. It is not clear whether these impacts are solely from ammonia or from a combination of factors but ammonia is a major potentially harmful constituent of municipal wastewater effluents. The consequence of discharges of nitrates and phosphorus is eutrophication. The impact depends on the support capacity of the receiving medium Zabel et al. 2001 . In Europe the Water Framework Directive European Commission 2000 indicates that .
