Recovery of Phosphorus and Nitrogen from Domestic Wastewater through Struvite Precipitation using Conical Fluidized Bed Reactor
No Thumbnail Available
Date
2019-10
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Ababa University
Abstract
Recovery of nutrients as struvite before it forms and accumulates is in line with sustainable
wastewater management. It prevents water pollution and enables use of the nutrients as
fertilizer to increase agricultural productivity. A bench-scale fluidized bed reactor (FBR) was
used to recover phosphate (PO4) and ammonium (NH4) through struvite crystallization, from
synthetic wastewater and aerobic digester domestic wastewater supernatant collected from,
Haile Garment Addis Ababa and Oromia Condominium Wastewater Treatment Plant.
Struvite crystallization is a promising nutrient recovery method. Its recovered precipitate can
be used as a slow release fertilizer and raw material for chemical industry. The objective of
this research was to examine the influence of different parameters affecting the performance of
FBR for phosphorus (P) and nitrogen (N) removal and recovery efficiencies.
In this study, the impacts of important factors on nutrient recovery in a laboratory scale (FBR)
were examined using synthetic wastewater to get optimal values. The nutrient recovery of the
FBR from real wastewater was also evaluated by using the optimum parameter values. The
recoveries of PO4 and NH4 were evaluated by changing the values of the following
parameters: pH (7.5-10), molar ratio of Mg/P (0.75-1.75), Hydraulic retention time (HRT = 15hr),
and
settling
time
(15-90min).
The
optimum
values
of
pH,
Mg/P,
HRT,
and
settling
time
were
found
to
be
9,
1.5:1,
2hr,
and
30min
respectively.
Under
these
optimum
values,
the
P
and
N
removal
efficiencies
of
conical
FBR
from
synthetic
and
real
wastewater
were
97%
and
95%
and 67.2% and 64.7%, respectively. Moreover, different techniques were used to enhance
nutrient recovery efficiency including use of a reactor that has three parts and insertion of
cones in each part.
The findings of the study show pH, Mg/P molar ratio, HRT, and settling time to be important
factors that influence Phosphorus and nitrogen removal efficiency in FBR. A conical FBR with
three distinct parts gives a good nutrient recovery through struvite precipitation.
Description
Keywords
Efficiency, fluidized bed reactor, Recovery, Removal, Struvite, nutrient, wastewater