Contaminant removal in septage treatment with vertical flow constructed wetlands operated under batch flow conditions

2015 ◽  
Vol 73 (4) ◽  
pp. 909-915 ◽  
Author(s):  
Valerie Siaw Wee Jong ◽  
Fu Ee Tang
Keyword(s):  
Constructed Wetlands ◽  
Palm Kernel ◽  
Oxygen Demand ◽  
Vertical Flow ◽  
Contaminant Removal ◽  
Efficient Operation ◽  
Palm Kernel Shell ◽  
Second Stage ◽  
Vertical Flow Constructed Wetlands ◽  
Study Results

Individual septic tanks are the most common means of on-site sanitation in Malaysia, but they result in a significant volume of septage. A two-staged vertical flow constructed wetlands (VFCWs) system for the treatment of septage was constructed and studied in Sarawak, Malaysia. Raw septage was treated in the first stage wetlands, and the resulting percolate was fed onto the second stage wetlands for further treatment. Here, the effects of a batch loading regime on the contaminant removal efficiency at the second stage wetlands, which included palm kernel shell within their filter substrate, are presented. The batch loading regime with pond:rest (P:R) period of 1:1, 2:2 and 3:3 (day:day) was studied. The improvement of the effluent redox condition was evident with P:R = 3:3, resulting in excellent organic matters (chemical oxygen demand and biochemical oxygen demand) and nitrogen reduction. The bed operated with P:R = 1:1 experienced constant clogging, with a water layer observed on the bed surface. For the P:R = 3:3 regime, the dissolved oxygen profile was not found to decay drastically after 24 hours of ponding, suggesting that the biodegradation mainly occurred during the first day. The study results indicate that a suitable application regime with an adequate rest period is important in VFCWs to ensure efficient operation.

scholarly journals Vertical flow constructed wetlands subject to load variations: an improved design methodology connected to outlet quality objectives

2015 ◽  
Vol 72 (5) ◽  
pp. 817-823 ◽  
Author(s):  
C. Boutin ◽  
S. Prost-Boucle
Keyword(s):  
Organic Matter ◽  
Constructed Wetlands ◽  
Oxygen Demand ◽  
Nitrification Rate ◽  
Vertical Flow ◽  
Design Standards ◽  
Rural Villages ◽  
Vertical Flow Constructed Wetlands ◽  
Nitrogen Concentrations ◽  
Improved Design

This study surveyed four campsites and four rural villages of major tourist interest, called tourist-interest or ti-villages, that were monitored for several years, generating over 70 performance balances for vertical flow constructed wetlands (VFCWs) that were intentionally scaled down for experimental trials. The wastewater effectively qualifies as domestic sewage, although relatively concentrated, with the campsites presenting particularly high nitrogen concentrations (122 gTKN L–1) (TKN: total Kjeldahl nitrogen). The applied daily loads were also particularly high, with some combinations of load parameters (hydraulic load, organic matter, TKN) leading to 400% overloading. Even under those drastic conditions, the quality of effluent remained excellent on the characteristic organic matter parameters, with removal performances always over 85%. Analysis of the dataset points to two major design thresholds: for campsites, in order to maintain a 73% nitrification rate even at the height of the summer season, the load applied onto the first stage filter in operation could achieve up to 600 gCOD m–2 day–1 (COD: chemical oxygen demand). For tourist-interest villages, in order to maintain an 85% nitrification rate, the load applied onto the second stage filter in operation could achieve up to 22 gTKN m–2.day–1. Here, VFCWs were demonstrated to robustly handle a massive increase in loads applied, providing the construction and operation stringently follow design standards and practices.

Constructed wetlands for the treatment of raw wastewater: the French experience

2014 ◽  
Vol 9 (3) ◽  
pp. 430-439 ◽  
Author(s):  
S. Troesch ◽  
F. Salma ◽  
D. Esser
Keyword(s):  
Organic Matter ◽  
Constructed Wetlands ◽  
Suspended Solids ◽  
Oxygen Demand ◽  
Vertical Flow ◽  
Small Communities ◽  
Vertical Flow Constructed Wetlands ◽  
French Experience ◽  
Raw Wastewater

Vertical flow constructed wetlands for small communities (<5,000 population equivalent) have been successfully developed in France since the 1990s (currently about 3'000 plants are in operation). This paper summarizes the results and efficiencies of 70 plants designed and built by Epur Nature or SINT. The results show clearly that the design performs well for organic matter removal and nitrification and makes sludge management easy. Therefore if well designed, such systems can achieve an outlet quality of BOD5 < 20 mg/L, chemical oxygen demand <90 mg/L, suspended solids <30 mg/L and TKN < 15 mg/L. In addition, some new configurations involving a French vertical first stage fed with raw sewage, patented by Epur Nature, are presented as an aid to reduce the global footprint.

scholarly journals Effectiveness of septage pre-treatment in vertical flow constructed wetlands

2017 ◽  
Vol 76 (9) ◽  
pp. 2544-2553 ◽  
Author(s):  
Beata Karolinczak ◽  
Wojciech Dąbrowski
Keyword(s):  
Constructed Wetlands ◽  
Municipal Wastewater ◽  
Oxygen Demand ◽  
Vegetation Period ◽  
Ammonia Nitrogen ◽  
Vertical Flow ◽  
Municipal Wastewater Treatment ◽  
Vertical Flow Constructed Wetlands ◽  
Hydraulic Load ◽  
Pre Treatment

Abstract Septage is wastewater stored temporarily in cesspools. A periodic supply of its significant quantities to small municipal wastewater treatment plants (WWTPs) may cause many operational problems. In the frame of the research, it has been proposed to utilize vertical flow constructed wetlands for pre-treatment of septage prior to its input to the biological stage of a WWTP. The aim of the work was to assess the effectiveness of pre-treatment in relation to factors such as: seasonality, hydraulic load, pollutants load of the VF bed and interactions between these factors. The results proved that application of a VF bed to septage pre-treatment can significantly reduce the concentration of pollutants (biochemical oxygen demand (BOD5): 82%, chemical oxygen demand (COD): 82%, total suspended solids (TSS): 91%, total nitrogen (TN): 47%, ammonia nitrogen (NH4-N): 70%), and thus decrease the loading of the biological stage of a WWTP. The mathematical models of mass removal process were created. They indicate that in case of all analysed parameters, removed load goes up with the increase of load in the influent. However, with the increase of hydraulic load, a decrease of the removed BOD5, COD, TSS and total phosphorus, and in vegetation period an increase of TN, can be observed in terms of load. There are no statistically significant effects of seasonality.

scholarly journals Performance of the first stage of the French system of vertical flow constructed wetlands with only two units in parallel: influence of pulse time and instantaneous hydraulic loading rate

2018 ◽  
Vol 78 (4) ◽  
pp. 848-859 ◽  
Author(s):  
Jorge A. García Zumalacarregui ◽  
Marcos von Sperling
Keyword(s):  
Constructed Wetlands ◽  
Loading Rate ◽  
Oxygen Demand ◽  
Feeding Time ◽  
Vertical Flow ◽  
Hydraulic Loading Rate ◽  
Hydraulic Loading ◽  
Vertical Flow Constructed Wetlands ◽  
Removal Efficiencies ◽  
Raw Wastewater

Abstract The technology of vertical flow constructed wetlands – French system for treating raw wastewater depends on several hydraulic factors, one of them being the duration of the pulse feeding and the resulting instantaneous hydraulic loading rate. This paper analyses two scenarios in the same system, the first of a faster feeding by pump and the second of a slower feeding by siphon, both with instantaneous hydraulic loading rate values lower than the literature recommendations. The system treated raw wastewater from a population equivalent of 100 p.e. in Brazil, and was comprised by only the first stage and two units in parallel. The shorter duration of feeding time and higher instantaneous hydraulic loading rate were associated with significantly higher chemical oxygen demand and total Kjeldahl nitrogen removal efficiencies, but with no significant differences in terms of biochemical oxygen demand (BOD) and suspended solids (SS). Oxygen concentrations and redox potential in the effluent were evaluated, together with the effluent flow rate profiles. The removal efficiencies were associated with the accumulation of solids in the upper part of the filter resulting from seven years of operation and to the operating hydraulic conditions, which are important elements in the performance of the system.

Nitrification in Vertical Flow Constructed Wetlands with Different Substrate and COD: N Ratio

2010 ◽  
Vol 96 ◽  
pp. 117-120 ◽  
Author(s):  
Xiao Li Han ◽  
Re Ti Hai ◽  
Wen Xin Wang
Keyword(s):  
Chemical Oxygen Demand ◽  
Constructed Wetlands ◽  
Oxygen Demand ◽  
Vertical Flow ◽  
Vertical Flow Constructed Wetlands ◽  
Peaty Soil

In this paper, the effect of chemical oxygen demand (COD) in the influent on nitrification in CWs with different substrate (peaty soil and turfy soil) was investigated. The results indicate that the influence of the substrate is insignificant but the COD: N ratio in the influent affects nitrification mainly.

The use of palm kernel shell (PKS) as substrate material in vertical-flow engineered wetlands for septage treatment in Malaysia

2015 ◽  
Vol 72 (1) ◽  
pp. 84-91 ◽  
Author(s):  
Valerie Siaw Wee Jong ◽  
Fu Ee Tang
Keyword(s):  
Removal Efficiency ◽  
Palm Kernel ◽  
Oxygen Demand ◽  
Pilot Scale ◽  
Substrate Material ◽  
Vertical Flow ◽  
Nitrate Accumulation ◽  
Palm Kernel Shell ◽  
N Removal ◽  
Load Removal

Abstract In this study, the treatment of septage (originating from septic tanks) was carried out in a pilot-scale, two-staged, vertical-flow engineered wetland (VFEW). Palm kernel shells (PKS) were incorporated as part of the VFEW's substrate (B-PKS), to compare its organic matter (OM) and nitrogen (N) removal efficiency against wetlands with only sand substrates (B-SD). The results revealed satisfactory OM removal with >90% reduction efficiencies at both wetlands B-PKS and B-SD. No increment of chemical oxygen demand (COD) concentration was observed in the effluent of B-PKS. Ammonia load removal efficiencies were comparable (>91% and 95% in wetland B-PKS and B-SD, respectively). However, nitrate accumulation was observed in the effluent of B-SD where PKS was absent. This was due to the limited denitrification in B-SD, as sand is free of carbon. A lower nitrate concentration was associated with higher COD concentration in the effluent at B-PKS. This study has shown that the use of PKS was effective in improving the N removal efficiency in engineered wetlands.

scholarly journals French vertical-flow constructed wetlands in mountain areas: how do cold temperatures impact performances?

2015 ◽  
Vol 71 (8) ◽  
pp. 1219-1228 ◽  
Author(s):  
S. Prost-Boucle ◽  
O. Garcia ◽  
P. Molle
Keyword(s):  
Constructed Wetlands ◽  
Nitrogen Removal ◽  
Winter Season ◽  
Oxygen Demand ◽  
Vertical Flow ◽  
Mountain Areas ◽  
Cold Temperatures ◽  
Vertical Flow Constructed Wetlands ◽  
Online Measurements ◽  
Solids Removal

The French version of vertical-flow constructed wetlands (VFCWs) is characterized by treating directly raw wastewater on a first-stage filter. VFCW is a well developed technology with more than 3,500 plants in operation in France. However, VFCW performance may be affected under the low temperatures reached in mountain areas during winter. The effect of cold conditions over 12 plants, ranging from 75 to 1,900 person equivalent and from 680 to 1,500 m above sea level, was studied over 2 years. The plant hydraulic loads, and air and filter temperatures were continuously measured. In addition, 24-h flow proportional sampling, at each stage of treatment, was conducted in summer (as a reference) and winter. Online measurements of ammonium and nitrates were also analyzed to describe the nitrogen removal dynamics. Since no impact on chemical oxygen demand (COD), biochemical oxygen demand (BOD) and suspended solids removal was observed, the effect of cold temperatures on nitrification was further analyzed. Nitrogen removal was relatively unaffected during winter season. Significant effects were confirmed only for the second stage for loads above 10 gTKN/m2/d (TKN: total Kjeldahl nitrogen). Temperature profiles allowed analysis of the filter buffer capacity in terms of freezing. Under minimal air temperature of −19 °C, no critical operation was observed, although design and operation recommendations can be provided to ensure suitable plant performances.

A decade of compact vertical flow constructed wetlands

2010 ◽  
Vol 62 (12) ◽  
pp. 2790-2800 ◽  
Author(s):  
C. M. Weedon
Keyword(s):  
Constructed Wetlands ◽  
High Performance ◽  
Oxygen Demand ◽  
Ammonia Removal ◽  
Vertical Flow ◽  
Hydraulic Residence Time ◽  
Organic Solids ◽  
Rate Analysis ◽  
Vertical Flow Constructed Wetlands ◽  
The Uk

Compact vertical flow constructed wetlands (1–2 m2/pe, down-flow, single bed, >500 mm sand depth) were first installed in the UK in 1998, since when over 40 such beds have been implemented. After ten years of experience, this approach to wastewater treatment is reviewed with respect to operation and maintenance, and water quality improvement. Despite considerable accumulation of organic solids on the surface of some beds after several years' operation, effluent distribution over and permeability of the bed surface, as well as oxygen transfer rates within the bed matrix, have remained satisfactory. Six years of data relating to a 432 m2 bed treating combined settled sewage and abattoir effluent have demonstrated consistently high performance. Suspended solids, biochemical oxygen demand and ammonia removal averaged 80, 98 and 91%, respectively, even at a hydraulic loading rate of 340 mm/d. At 12 mm/d, removal was even more thorough. In contrast, accumulation of iron-rich organic solids on the bed's surface, which led to the bed becoming completely flooded, markedly decreased nitrification, although percentage total nitrogen removal was double that of the non-flooded bed. Flow rate analysis through the bed allowed calculation of percentage matrix saturation by effluent during operation, and operational hydraulic residence time (3.83 h), the implications of which are discussed.

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