ABSTRACT
The problem of water Scarcity, water pollution and
cost of accessing water for domestic needs have become growing concerns to the
ever increasing global population. Waterwaterremediation has long been accepted
as a viable option to mitigate water scarcity. This research examines the
potentials of an environmentally friendly technique of using local but modified
tropical plant materials in remediation of greywater for re-use. Column
adsorption experiment was conducted using synthesized and characterized Biochar
and Activated Carbon made from Shea tree (Vitellariaparadoxa), African
Mahogany tree (KhayaSenegalenses) and the Fig tree (FicusSycomous)
as filter media in constructed filter columns made from polyvinyl chloride
pipes. Greywater Samples from Ahmadu Bello University Zaria‘s student hostel
were passed through these filters at a hydraulic loading rate of 0.033m3/m2/day
for a period of 21 days. The parameters assessed in this experiment were
Electrical Conductivity (EC), Biological and Chemical Oxygen Demand (BOD and
COD), Ammonium Nitrogen (NH4-N), Nitrate Nitrogen (NO3-N),
Total Nitrogen (Tot-N), available Phosphate (PO4-P), Total
Phosphorus (Tot-P) and pH. The results obtained showed high treatment
efficiencies for both Activated Carbon and Biochar on all tested parameters
except for NH4-N in which AC had a low efficiency of 49% at one
instance. Activated Carbon had (85 – 95%) in remediating organic matter, (61
-81%) in remediating EC, (39 – 89%) in remediating NH4-N, (93 –
100%) for NO3-N, 92 – 99% for Total Phosphorus. Biochar showed 88 –
92% efficiency in remediating Total Phosphorus, 91 – 99% for NO3-N,
68 – 89% for NH4-N, 85 – 90% for EC and 76 – 90% for organic matter
removal. The factors of time, particle size, activation status and parent
material used in the filters were used to determine the efficiency of the
filters and the results showed that time, parent material used, and activated
status of the filters had significant effect on the performance of the filters
while differences in particle sizes had little effect on the performance. It
could be concluded therefore that biochar compared favourably with activated
carbon in the remediation of greywater, which is more complex to synthesize and
cost more to produce. In addition, because of the ease of production and
availability of raw materials in the tropics, biochar can be used to remediate
greywater and replace Activated Carbon in some water treatment systems.
CHAPTER ONE
INTRODUCTION
1.1 Background of
the study
With the continuous annual increase in the world population
(lowest increase being 1.1%) there is need to manage our natural resources.
Water, which is one of these basic resources for human survival and
socioeconomic development, needs to be managed efficiently. The United Nations
has estimated that the use of water has increased six fold in the 20th century
and that by the year 2025, about 1.8 billion people will have absolute water
scarcity conditions (with an annual water supply of less than 500m3 per capita)
and also that two third (2/3) of the world population will live under water
stress (with an annual water supply of less than 1700m3 per capita) (U.N-Water
Report, 2006). This population increase will have adverse effects on developing
countries where 82% of the world live and experience water scarcity (Dalahmeh,
2013). There is therefore need to properly manage and utilize existing water
resources especially in the developing countries.
The reality of water scarcity, coupled with the increased
potential health risk posed by greywater pollution necessitates a swift
solution hence the idea of using locally available materials like biochar as a
means of improving water quality, sanitation and reducing environmental
problems has become attractive.This study seeks to find simple inexpensive and
locally available materials like charcoal and sand to solve environmental
problems posed by water scarcity and water pollution.
Wood from locally available tropical trees waspyrolyzed at a
temperature of 650oC and the biochar derived wascharacterized and treated. Its
ability to adsorb certain major pollutants from the collected greywater was
determined.
Greywater or sullage is defined as wastewater generated from
kitchens and wash-hand basins, showers and baths, which, because it is nearly
as clean as potable water, can be recycled onsite for uses such as toilet
flushing, landscape irrigation and constructed wetlands (Barker and English,
2011).Biochar refers to biomass-derived char product most often used as cooking
fuel (Kearnset al, 2014). It is a name for charcoal when it is used for a
particular purpose such as soil amendment, water treatment, etc. (Kearns,
2012).Pyrolysis is a thermochemical decomposition of organic materials at
elevated temperature in the absence of oxygen. It involves the simultaneous
change in both chemical and physical compositions of the organic materials. The
process is irreversible. Pyrolysis produces gas, liquids and a solid product
rich in carbon.
1.2 Statement of
the research Problem
Greywater, which accounts for approximately 50-80% of total
household wastewater mostly ends up in receiving water bodies (Li et al.,
2009). The provision of inadequate sanitation and wastewater disposal
facilities leads to environmental and public health problems which is
responsible for 1.8 million deaths annually (Corcoran et al., 2010; WHO Report,
2009). Although centralized wastewater systems are common in industrialized
countries, they are complex and expensive to construct and operate. This
however is not a viable option for most communities in developing countries.
There is therefore the need to source for simple and affordable environment
friendly techniques to treat greywater.
1.3 Justification
of the Study
Previous studies and designs utilize activated carbon as
adsorbents in water treatment systems. Recent studies however showed that
biochar especially those with high lignin
content when pyrolyzed at
temperatures above 450oC show similar molecular structure like that of
activated carbon and can therefore be a possible replacement to Activated
Carbon (McLaughlin et al., 2009; Kearns, 2012). This study aims to
experimentally determine the effectiveness of biochar in greywater remediation.
Biochar is cheaper, available and more environmentally friendly when compared
to activated carbon, ion exchange resins, membrane filtration, reverse osmosis
and nano filtration (Kearns, 2012). Biochar production techniques are also
cheap and easy for local communities and so, this might be a better treatment
option for community wastewater remediation especially in developing countries.
1.4 Aim and
Objectives
This research aims to determine the effectiveness and
efficiency of biochar derived from different lignin containing trees; Vitellariaparadoxa
(Shea Tree), Khayasenegalenses (Mahogany), Ficussycomous(Fig) in remediating
greywater.
The research has these following specific objectives.
i. To produce biochar and activated carbon from different parent
material
ii. To use the biochar and activated carbon to make filters with
physical properties like those of sand filters.
iii. To determine the efficiency of the prepared filters in
remediating chemical and
physical parameters; pH, Electronic Conductivity (EC),
Ammonium Nitrogen (NH4-N), Total Nitrogen (Tot-N), Phosphate Phosphorus (PO4
-P), Nitrate Nitrogen (NO3-N), Biological Oxygen Demand and Chemical Oxygen
Demand
(COD) from greywater.
iv. To compare the performance of the biochar with activated
carbon made from same parent materials in greywater remediation.
v. To determine the effect of particle size, time and parent
material in adsorbing the stated parameters.
1.5 Scope and
Limitation of the study
This studywas to determine the effectiveness of biochar from
three specifically identified tropical lignin containing trees (Vitellariaparadoxa,
Khayasenegalenses, Ficussycomous) in remediating greywater fromSuleiman Hostel
of Ahmadu Bello University Zaria (A.B.U). Physical and chemical parameters
tested were: pH, Electrical Conductivity (EC), Amonium Nitrogen (NH4-N), Total
Nitrogen (Tot-N), Phosphate-Phosphorus(PO4-P), Total Nitrogen, Nitrate Nitrogen
(NO3-N), Chemical Oxygen Demand (COD) and(BOD)Biological Oxygen Demand. The
constant mass of Carbon used throughout the experiment and the variation in
daily concentration of pollutants in the greywater source however served as
limitations in this study. It was addresses by adding an extra column which
served as control to monitor changes in the greywater. This research was
limited to Greywater and not industrial or other domestic wasterwater.
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Item Type: Project Material | Size: 103 pages | Chapters: 1-5
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