Bioengineering Applications of an Approximation of Sparse Time-Frequency Method
7.1. Problem Formulation
The uncontrolled discharge of wastewater from slaughterhouses in Nigeria has been identified as one of the major sources of environmental degredation because they pollute both surface and underground waters, rendering them infit for human consumption and utilization for other purposes, and thus has very severe consequences, not only for human existence, but also for ecological sustainability. CW has been identified as a viable option for slaughterhouse wastewater treatment. The technology has evolved in developed world from the application of the basic concepts to more complex hybrid and integrated systems. Despite the numerous publications on CWs over the past decades, and its recognition as a viable technology for treating wastewater, there is a notable gap in literature regarding its potentials for slaughterhouse effluent bioremediation in developing countries, and studies evaluating CWs performance for of slaughterhouse wastewater treatment are fairly limited both in the temperate and the tropical climates. There is little or no published literature on application of CW for slaughterhouse wastewater treatment in Nigeria.
Wetland substrates support the wetland vegetation, provide sites for biochemical and chemical transformations, and provide sites for storage of removed pollutants. Gravel is the most common media used in CWs. Very important is the fact that substrate materials must be cheap and also locally available for easy implementation of CWs. Recently, studies of the use on non-conventional materials as CW substrates have increased. Several studies have investigated different types of organic solids (corn cobs, green waste, wheat straw, softwood and hardwood) as alternative wetland media (Cameron and Schipper 2010, Tee et al., 2009). Most of the studies on the feasibility of non-conventional substrates were performed on experimental or pilot scales, and some using synthetic wastewater. Treatments in experimental or lab-scale systems do not adequately describe the processes that occur in field-scale systems, due to factors like significant edge effects and synthetic wastewater cannot be compared to real wastewater, which is much more complex (Kadlec and Wallace 2009). There are also lab-scale studies on the efficacy of PKS as a wetland substrate (Chong et al., 2009; Jong and Tang, 2015) with varying degrees of the PKS processing prior to use, which may not be achievable in large-scale systems. Studies on PKS capacities in real-life CWs, its effective lifespan in such a system and its influence on water flow in a CW are lacking in wetland literature. Nguyen et al., (2013) in their review of the applicability of agricultural waste and by-products for the sequestration of heavy metals from wastewater, stated that agricultural waste has shown equal or even increased adsorption capacities compared to conventional material, but emphasized the existence of various gaps that require further investigation, including assessing the performance of agricultural waste and by-products under real wastewater systems. There is need to supplement these gaps.
Also, the knowledge that statistically different results have been obtained for different macrophyte species performance raises the interest in experimenting with more macrophytes.
Most studies on CW performance were performed using the system as polishing units after secondary treatment. The literature on emergent macrophytes for CWs is quite extensive (Burke,
2011, Baskar et al., 2014, Dipu et al., 2010) but most of the information concerns the tertiary treatment of sewage. Studies on macrophytes survival and growth in CWs for secondary treatment of slaughterhouse effluent is very limited. Typha spp and Phragmites spp have been extensively evaluated for use in CWs, but there is little documentation on the use of other potential macrophytes such as Colocasia Esculent and Thalia Geniculata as emergent macrophytes for CWs.
CHAPTER THREE MATERIALS AND METHODS 3.1 Description of the Study Area
The research was confined to Anambra State due to funding constraints, but its recommendations will be applicable to other states in Nigeria. Ecologically, the state falls within the rainforest zone of Nigeria. Monthly normal climate data (2006-2015) from the NIMET Synoptic Station, Awka indicates that temperatures reach a maximum of 35.7℃ in February and a minimum of 20.4℃ in January. The average annual rainfall in the study area is 1923.7mm.
Most of the precipitation falls from April to October, and the area is very dry from December through March. The average annual potential evapotranspiration in the study area was calculated as 1965.8mm using the Thornthwaite method.
Seven slaughterhouses out of the major ones in Anambra State that dealt mainly on beef were selected for the wastewater characterization and treatability studies. The seven slaughterhouses were randomly selected to ensure that the major cities of Anambra State were covered and at least two from each senatorial district. The slaughterhouses are shown in Figure 3.1, and their coordinates are: the Umunya slaughterhouse in Oyi L.G.A (6.207611667oN and 6.905594oE);
Nkwo-Nnewi slaughterhouse in Nnewi North L.G.A (6.019105oN and 6.90853oE); Amansea slaughterhouse in Awka-North L.G.A (6.248326667oN and 7.136735oE); Eke-Ekwulobia slaughterhouse in Aguata L.G.A (6.018026944oN and 7.080091oE); Agulu slaughterhouse in Anaocha L.G.A (6.093185oN and 7.031785oE); Eke-Awka Etiti slaughterhouse in Idemili South L.G.A (6.03555oN and 6.962635oE); and Ochanja slaughterhouse in Onitsha South L.G.A (6.133826667oN and 6.785008 oE). They varied in size from small private facilities to large municipal ones, and they all had approval from the local government authorities. The Agulu slaughterhouse, which was the selected slaughterhouse for the on-site bio-remediation system
implementation, is in Agulu town. The town has one of the largest populations in the state. Its cordinates are latitudes 6.04oN and 6.09oN and longitudes 7.00oE and 7.03oE, and it lies within
Figure 3.1 Map of Anambra State showing the study areas
the boundaries of the Capital Territory of the State. It lies within latitudes 6.04oN and 6.09oN and longitudes 7.00oE and 7.03oE. It covers an area of about 85km2 and shares boundaries with eight towns namely: Nise in the North, Mbaukwu in the North-East, Awgbu in the South and South-East, Nanka in the South, Nri in the North-East, Adazi to the West, and Obeledu and Agulu Uzoigbo to the South-West. Agulu lies along the main road that links the capital city (Awka) with Ekwuluobia and further to Imo State. The slaughterhouse is located in Obeagu village, along the Adazi-Agulu-Agulu Uzoigbo link road and serves as a major meat source for the surrounding towns. The total area of the slaughterhouse is around 1 hectare.
The summary of the experimental procedure is show in Figure 3.2
Figure 3.2 Summary of the experimental procedure Start
Preliminary Investigations Selection of the Study Area
Pilot Studies
Macrophyte growth in slaughterhouse effluent
Macrophyte survival in PKS
Column Experiment Estimation of design
model constants
Durability of PKS in CW
Characterization of wastewater from
slaughterhouses
Design and construction of a field scale PKS
based HSSF CW
Evaluation of treatment performance
Evaluation of hydrodynamic performance
Multiple regression analysis
Structured interview
Tracer test
Application of residence time distribution models
CFD modelling
Optimization of system design
3.2 Wastewater Characterization Study