CZECH TECHNICAL UNIVERSITY IN PRAGUE FACULTY OF CIVIL ENGINEERING DEPARTMENT OF SANITARY AND ECOLOGICAL ENGINEERING ENVIRONMENTAL, ENERGY AND OPERATION RELATED ASPECTS OF DECENTRALIZED MANAGEMENT OF WASTEWATERS AND STORMWATERS IN SMALL MUNICIPALITIES DIPLOMA THESIS MARKÉTA VACKOVÁ Supervisor: Doc. Ing. David Stránský, Ph.D. January 2018 DECLARATION I declare that this thesis has been composed solely by myself and that it has not been submitted, in whole or in part, in any previous application for a degree. I declare that all used information sources are properly referenced according to Methodical guideline on academic publication ethics. Prague, 7. 1. 2018 ……………………………………………… ACKNOWLEDGEMENTS I would like to thank my thesis supervisor, doc. Ing. David Stránský, Ph.D., for helping me choose an interesting and meaningful topic, for his invaluable professional advice, and for being always patient and helpful. I would like to express my sincere gratitude for all the time he has invested in helping me, for always being available, and for presenting his wise opinions with witty sense of humour. ABSTRACT This thesis focuses on environmental, energy and operation-related aspects of decentralised wastewater and stormwater management in small municipalities. The aim of this thesis is to compare centralised and decentralised wastewater and stormwater management in municipalities with less than 500 PE. First part of the thesis explains the rationale for decentralisation of wastewater and stormwater management, describes traditional centralised approach to wastewater and stormwater management, presents basic concepts and technologies used for decentralised wastewater management, introduces sustainable urban drainage systems, summarises Czech and European legislation related to wastewater and stormwater management, and describes the authorisation process for wastewater treatment plant construction and discharges of treated wastewater. Second part compares centralised and decentralised wastewater and stormwater management based on environmental, energetic and operational reliability criteria. Three cases studies are used to calculate pollution loads to receiving environment, energy requirements, and system reliability of centralised and decentralised option. KEY WORDS: decentralized wastewater management, SUDS, WWTP reliability, energy consumption of wastewater treatment plant ANOTACE Diplomová práce se zabývá environmentálními, energetickými a provozními aspekty decentralizovaného nakládání s odpadními vodami v malých obcích. Cílem práce je porovnat centralizované a decentralizované způsoby nakládání s odpadními a dešťovými vodami v obcích s méně než 500 p.e. První část práce jmenuje výhody a nevýhody decentralizovaného čištění odpadních vod a nakládání s dešťovými vodami, popisuje tradiční přístup k městskému odvodnění a koncepty a technologie používané pro decentralizovaný způsob nakládání s odpadními a dešťovými vodami. Součástí práce je přehled české a evropské legislativy vztahující se k problematice městského odvodnění a popis procesu povolování výstavby ČOV a vypouštění odpadních vod v České republice. V druhé části práce je na třech konkrétních případech provedeno porovnání a zhodnocení centralizovaného a decentralizovaného způsobu nakládání s odpadními vodami z hlediska produkovaného znečištění, energetických nároků a spolehlivosti jednotlivých systémů. KLÍČOVÁ SLOVA: decentralizované nakládání s odpadními vodami, SUDS, spolehlivost ČOV, energetické nároky na provoz ČOV Contents: 1 INTRODUCTION ............................................................................................................................... 5 2 THEORETICAL BACKGROUND .......................................................................................................... 8 2.1 Influence of urbanization on natural hydrological cycle .......................................................... 8 2.2 Centralised systems ................................................................................................................. 9 2.3 Decentralised systems ............................................................................................................ 14 2.3.1 Wastewater treatment.................................................................................................... 14 2.3.2 Stormwater management ............................................................................................... 30 2.4 Determination of optimal degree of centralization ............................................................... 40 2.5 Related legislation .................................................................................................................. 44 2.6 Authorisation of wastewater discharges in the Czech Republic ............................................ 46 2.6.1 Water authority proceeding – authorisation of municipal WWTPs ................................ 47 2.6.2 Product approach – WWTPs for less than 50 PE bearing the CE marking ...................... 48 3 THESIS GOALS ................................................................................................................................ 51 4 CASE STUDIES ................................................................................................................................ 52 4.1 Tisovec .................................................................................................................................... 52 4.2 Chlumětín ............................................................................................................................... 53 4.3 Bořice...................................................................................................................................... 55 5 METHODS ...................................................................................................................................... 57 5.1 Environmental assessment .................................................................................................... 57 5.2 Energy assessment ................................................................................................................. 59 5.3 Operational reliability assessment ......................................................................................... 64 6 RESULTS ......................................................................................................................................... 68 6.1 Environmental assessment .................................................................................................... 68 6.1.1 Strictest scenario ............................................................................................................. 68 6.1.2 Tolerant scenario ............................................................................................................. 69 6.1.3 Declared efficiency scenario ........................................................................................... 71 6.1.4 Environmental assesment summary ............................................................................... 78 6.2 Energy assessment ................................................................................................................. 78 6.2.1 Energy requirements for wastewater treatment – centralised WWTP compared to small- scale systems ............................................................................................................................ 78 6.2.2 On-site reuse systems – energy requirements for operation compared to energy that would be needed for treatment and distribution of the same volume of potable water ....... 83 6.2.3. Energy consumed for decentralised wastewater and stormwater management versus centralised WTP and WWTP .................................................................................................... 85 6.2.4 Energy assessment summary .......................................................................................... 86 6.3 Operational reliability assessment ......................................................................................... 86 6.3.1 Operational reliability assessment summary .................................................................. 93 7 DISCUSSION ................................................................................................................................... 94 8 CONCLUSIONS ............................................................................................................................... 96 9 REFERENCES .................................................................................................................................. 98 1 INTRODUCTION The accession of Czech Republic (CZ) to the European Union (EU) in 2004 had a major influence on development of public infrastructure for collecting and treatment of municipal wastewaters. To comply with EU legislation, it was necessary to accelerate the implementation of sanitation infrastructure projects. The percentage of population connected to a sewage network rose from less than 78% in 2003 to 84.7% in 2016 [17]. However, year-on-year increase in the share of population with access to public sanitation network has been stagnating in the past years [12], since most of the major settlements are now in compliance with the obligation imposed by the EU legislation. Recently, the focus has been turning to small municipalities where the implementation of wastewater collecting and treatment systems is technically and economically more challenging.