The development of vertical flow constructed wetlands treating raw wastewater in France has proved to be very successful over the last 20 years. In view of this a survey was carried out on more than 80 plants in order to study their performance and correct the design if necessary. This study shows that such systems perform well in terms of respecting the goals of both low level outlet COD and SS and nitrification. Pollutant removal performance in relation to the loads handled and the specific characteristics of the plants were investigated. Nitrification is shown to be the most sensitive process in such systems and performance in relation to sizing is discussed. Such systems, if well designed, can achieve an outlet level of 60 mg L(-1) in COD, 15 mg L(-1) in SS and 8 mg L(-1) in TKN with an area of 2 - 2.5 m2.PE(-1). The sludge deposit on the first stage must be removed after about 10-15 years.

उपचार आर्द्रभूमियााँ ‘जैविक अपमिष्ट जल’ िें सातिाृं खृंड है उपचार श्ृंखर ला, जो सीिेज उपचार के विज्ञान और तकनीक की अत्याधुननक प्रस्तुनत देती है। आर्द्रभूमि प्रणामलयों के प्रिुख प्रकार इस खृंड िें िामिल हैं, नाितः: (i) क्षैनतज प्रिाह आर्द्रभूमि; (ii) ऊध्िारधर प्रिाह आर्द्रभूमि; (iii) फ्रें च ऊध्िारधर प्रिाह आर्द्रभूमि; (iv) सघन आर्द्रभूमि; (v) िुक्त जल सतह आर्द्रभूमि; (vi) उपचार आर्द्रभूमि के अन्य अनुप्रयोि। पुस्तक िुख्य अिधारणाओृं, कािकाजी मसद्धाृंतों, अपेक्षक्षत प्रदिरन, डडजाइन िानदृंड, डडजाइन उदाहरण, ननिारण पहलुओृं और पररचालन द्रदिाननदेिों को स्पष्ट और उपचारात्िक तरीके से प्रस्तुत करती है। पुस्तक को उपचार के क्षेत्र के िीर्र वििेर्ज्ञों की एक अृंतरराष्रीय टीि ने मलखा है। श्ृंखर ला के बारे िें: इस बहुप्रिृंमसत श्ृंखर ला िें सात पाठ्यपुस्तकें िामिल हैं - वप्रटृं िें या िुक्त-अमभिि ई-पुस्तकों के रूप िें उपलब्लध - जो जैविक अपमिष्ट जल उपचार के विज्ञान और तकनीक की एक अत्याधुननक प्रस्तुनत प्रदान करती हैं। विकमसत और विकासिील देिों िें छात्रों, िोधकतारओृं और अभ्यासकों द्िारा श्ृंखर ला के सभी खण्डों का व्यापक रूप से उपयोि क्रकया िया है। जैविक अपमिष्ट जल उपचार श्ृंखर ला िें िीर्कर हैं: खृंड 1: अपमिष्ट जल के लक्षण, उपचार और ननपटानखृंड 2: अपमिष्ट जल उपचार के िूल मसद्धाृंतखृंड 3: अपमिष्ट स्स्िरीकरण तालाबखृंड 4: अिायािीय ररएक्टरखृंड 5: सक्रिय कीचड़ और िायुजीिी बायोक्रिल्ि ररएक्टरखृंड 6: कीचड़ उपचार और ननपटानखृंड 7: उपचार आर्द्रभूमियााँ आईएसबीएन: 9781780408767 (पेपरबैक) आईएसबीएन: 9781789062564 (ई-पुस्तक)

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French vertical flow constructed wetlands, treating directly raw wastewater, have become the main systems implemented for communities under 2,000 population equivalent in France. Like in sludge drying reed beds, an organic deposit layer is formed over time at the top surface of the filter. This deposit layer is a key factor in the performance of the system as it impacts hydraulic, gas transfers, filtration efficiency and water retention time. The paper discusses the role of this deposit layer on the hydraulic and biological behaviour of the system. It presents results from different studies to highlight the positive role of the layer but, as well, the difficulties in modelling this organic layer. As hydraulic, oxygen transfers, and biological activity are interlinked and impacted by the deposit layer, it seems essential to focus on its role (and its quantification) to find new developments of vertical flow constructed wetlands fed with raw wastewater.

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Combined sewer systems are designed to transport stormwater surface run off in addition to the dry weather flows up to defined limits. In most European countries, hydraulic loads greater than the design flow are discharged directly into receiving water bodies, with minimal treatment (screening, sedimentation), or with no treatment at all. One feasible solution to prevent receiving waters from strong negative impacts seems to be the application of vertical flow constructed wetlands. In Germany, first attempts to use this ecological technology were recognized in early 1990s. Since then, further development continued until a high level of treatment performance was reached. During recent years the national "state-of-the-art" (defined in 2005) was adapted in other European countries, including France and Italy. Against the background of differing national requirements in combined sewer system design, substantial developmental steps were taken. The use of OPEN ACCESSWater 2013, 5 2 coarser filter media in combination with alternating loadings of separated filter beds allows direct feedings with untreated combined runoff. Permanent water storage in deep layers of the wetland improves the system's robustness against extended dry periods, but contains operational risks. Besides similar functions (but different designs and layouts), correct dimensioning of all approaches suffers from uncertainties in long-term rainfall predictions as well as inside sewer system simulation tools.

Intensive use of phosphates has resulted in high P levels in surface waters and therefore eutrophication problems. Over the last decade many studies have revealed the advantage of using specific materials with efficient phosphorus retention capacities. Recent studies state that Ca materials are of particular interest for long-term retention of P, but can induce negative effects. To improve P retention and avoid negative counter-effects we tested the potential of natural apatites. Apatite sorption was evaluated using batch and open reactor experiments. Batch experiments identify sorption mechanisms and the influence of the ionic characteristics of the solution; open reactor experiments evaluate sorption capacities in relation to the ionic composition of the solution and biomass development. In parallel, observation of the material by electron microscopy was used to give more precision information about the mechanisms involved. This work reveals the strong chemical affinity between apatites and phosphorus. Compared to other calcareous materials apatite is better able to maintain low outlet P levels. After more than 550 days feeding, sorption was still present and low P outlet levels were still being obtained when sufficient contact time and calcium content in the solution were ensured. This work demonstrates the advantages of using apatites for phosphorus removal in constructed wetlands. The behaviour of apatite in phosphorus retention is explained and its suitability for use in such extensive systems defined.