An evaluation of duckweed-based pond systems as an alternative option for decentralised treatment and reuse of wastewater in Zimbabwe

2003 ◽  
Vol 48 (2) ◽  
pp. 323-330 ◽  
Author(s):  
I. Nhapi ◽  
J. Dalu ◽  
J. Ndamba ◽  
M.A. Siebel ◽  
H.J. Gijzen
Keyword(s):  
Removal Efficiency ◽  
Phosphorus Removal ◽  
Field Measurements ◽  
Good Alternative ◽  
Full Scale ◽  
Design Criteria ◽  
Nitrogen And Phosphorus ◽  
Nitrogen And Phosphorus Removal ◽  
High Nutrient ◽  
Duckweed Pond

A study was carried out in Zimbabwe to evaluate the performance of duckweed ponds as an option for treating and reusing wastewater in small, decentralised communities. The study focused on nitrogen and phosphorus removal, operational problems, and duckweed application. Two full-scale trial plants at Nemanwa and Gutu-Mupandawana growth points were used. Sewage samples were collected and analysed monthly from September 2000 to August 2001 for NO3, NH4-, TKN, TP, COD, and other field measurements. The duckweed was harvested daily and fed to chickens. The Nemanwa plant had high nutrient levels due to nil outflows caused by water rationing in the area. The Gutu effluent had averages of 38.7 ± 23.1 mg/l TN and 7.5 ± 2.4 mg/l TP which are above the respective Zimbabwean standards of 10 mg/l TN and 1 mg/l TP. COD removal efficiency at Gutu was poor at 45%. The performance of Gutu and Nemanwa plants suffered from inappropriate design especially pond depth and short-circuiting. The duckweed died off in the November-January period, this being attributed to excessive levels of ammonia. It was concluded that the duckweed pond systems would offer a good alternative for managing and reusing wastewater at community level provided due regard is paid to appropriate design criteria.

Comparison of nitrogen and phosphorus removal efficiency between two types of baffled vertical flow constructed wetlands planted with Oenanthe Javanica

2020 ◽  
Vol 81 (9) ◽  
pp. 2023-2032
Author(s):  
Jingqing Gao ◽  
Lei Yang ◽  
Rui Zhong ◽  
Yong Chen ◽  
Jingshen Zhang ◽  
...  
Keyword(s):  
Removal Efficiency ◽  
Phosphorus Removal ◽  
Sewage Treatment ◽  
Drinking Water Treatment ◽  
Domestic Sewage ◽  
Good Choice ◽  
Vertical Flow ◽  
Nitrogen And Phosphorus ◽  
Nitrogen And Phosphorus Removal ◽  
Oenanthe Javanica

Abstract The environmental problems related to rural domestic sewage treatment are becoming increasingly serious, and society is also concerned about them. A baffled vertical flow constructed wetland (BVFCW) is a good choice for cleaning wastewater. Herein, a drinking-water treatment sludge-BVFCW (D-BVFCW) parallel with ceramsite-BVFCW (C-BVFCW) planted with Oenanthe javanica (O. javanica) to treat rural domestic sewage was investigated, aiming to compare nitrogen and phosphorus removal efficiency in different BVFCWs. A removal of 23.9% NH4+-N, 24.6% total nitrogen (TN) and 76.7% total phosphorus (TP) occurred simultaneously in the D-BVFCW; 56.4% NH4+-N, 60.8% TN and 55.2% TP respectively in the C-BVFCW. The root and plant height increased by an average of 7.9 cm and 8.3 cm, respectively, in the D-BVFCW, and by 0.7 cm and 1.1 cm, respectively, in the C-BVFCW. These results demonstrate that the D-BVFCW and C-BVFCW have different effects on the removal of N and P. The D-BVFCW mainly removed P, while C-BVFCW mainly removed N.

Background to Biological Phosphorus Removal

1983 ◽  
Vol 15 (3-4) ◽  
pp. 1-13 ◽  
Author(s):  
James L Barnard
Keyword(s):  
Activated Sludge ◽  
Phosphorus Removal ◽  
Plug Flow ◽  
Full Scale ◽  
Biological Phosphorus Removal ◽  
Anaerobic Conditions ◽  
Paper Briefly ◽  
Nitrogen And Phosphorus ◽  
Nitrogen And Phosphorus Removal ◽  
Biological Phosphorus

This paper briefly summarizes the early work on phosphorus removal in activated sludge plants in the U.S.A. and observed that such removals only occurred in low SRT plants of the plug flow type and in the Phostrip plants, neither designed for full nitrification. The discovery of simultaneous nitrogen and phosphorus removal, as well as full-scale experiments are discussed. The Phoredox process was proposed utilizing internal recycling for the removal of nitrates and an anaerobic first stage in which the incoming feed is used to obtain the necessary anaerobic conditions, essential as a conditioning step for the uptake of phosphorus. Proposed mechanisms are discussed.

Enhancing nitrogen and phosphorus removal in the BUCT–IFAS process by bypass flow strategy

2015 ◽  
Vol 72 (4) ◽  
pp. 528-534 ◽  
Author(s):  
Yang Bai ◽  
Xie Quan ◽  
Yaobin Zhang ◽  
Shuo Chen
Keyword(s):  
Carbon Source ◽  
Removal Efficiency ◽  
Phosphorus Removal ◽  
P Uptake ◽  
Flow Mode ◽  
Bypass Flow ◽  
Nitrogen And Phosphorus ◽  
Nitrogen And Phosphorus Removal ◽  
University Of Cape Town ◽  
P Removal

A University of Cape Town process coupled with integrated fixed biofilm and activated sludge system was modified by bypass flow strategy (BUCT–IFAS) to enhance nitrogen and phosphorus removal from the wastewater containing insufficient carbon source. This process was operated under different bypass flow ratios (λ were 0, 0.4, 0.5, 0.6 and 0.7, respectively) to investigate the effect of different operational modes on the nitrogen (N) and phosphorus (P) removal efficiency (λ = 0 was noted as common mode, other λ were noted as bypass flow mode), and optimizing the N and P removal efficiency by altering the λ. Results showed that the best total nitrogen (TN) and total phosphorus (TP) removal performances were achieved at λ of 0.6, the effluent TN and TP averaged 14.0 and 0.4 mg/L meeting discharge standard (TN < 15 mg/L, TP < 0.5 mg/L). Correspondingly, the TN and TP removal efficiencies were 70% and 94%, respectively, which were 24 and 41% higher than those at λ of 0. In addition, the denitrification and anoxic P-uptake rates were increased by 23% and 23%, respectively, compared with those at λ of 0. These results demonstrated that the BUCT–IFAS process was an attractive method for enhancing nitrogen and phosphorus removal from wastewater containing insufficient carbon source.

scholarly journals Use of zeolites for macronutrients removal from wastewater

2019 ◽  
Vol 12 (1) ◽  
pp. 150-161
Author(s):  
Barbora Urminská ◽  
Ján Derco ◽  
Ronald Zakhar ◽  
Adriana Korpicsová
Keyword(s):  
Removal Efficiency ◽  
Phosphorus Removal ◽  
Natural Zeolite ◽  
Ammonium Nitrogen ◽  
Nitrogen And Phosphorus ◽  
Nitrogen And Phosphorus Removal ◽  
Physical Chemical ◽  
Synthetic Zeolites ◽  
Modified Zeolites ◽  
Preliminary Research

Abstract Natural or synthetic zeolites have unique physical, chemical and structural properties that predetermine their use in many processes, including wastewater treatment. This study presents the results of our preliminary research in the field of nitrogen and phosphorus removal using adsorption and adsorptive ozonation with natural and modified zeolites. Iron-modified zeolite was the most efficient for the removal of ammonium nitrogen by adsorption. Phosphorus removal efficiency using adsorption was relatively low and natural zeolite was not suitable for the phosphorus removal at all. Ozone had no significant impact on the removal efficiency. Regeneration of loaded zeolites with ozone has also been studied. This method was partly efficient but it needs be further examined.

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