CHAPTER 1
INTRODUCTION
1.1
BACKGROUND STUDY
Poultry slaughterhouse wastewater is one of the sources of environmental pollution. This slaughterhouse industry operates by slaughtering live chicken and processes them into carcass which is prepared for our consumption. The production of the wastewater is either from the washing equipment and facilities or from the process itself. Besides that, a large amount of wastewater generated by poultry slaughterhouse which has a high amount of biodegradable organic matter, suspended and colloidal matter such fats, cellulose and proteins (Sugito et al., 2016). Apart from that, Sugito et al., (2016), also mentioned that there are chemical-physical waste and microbes contained in the chicken slaughterhouse wastewater. The microbes are such as Bacillussubtilis, as Bacillussubtilis, Bacillusthuringiensis, and Lysinibacillusfusiform. and Lysinibacillusfusiform. Poultry slaughterhouse and chicken processing plants are one of the widest spread plants in Malaysia. These plants produce relatively high amount of wastewater between 8 and 15 L per bird slaughtered (200 – 700 700 m3/day). Blood, feathers, offal (remnants of intestine and cloaca pieces), bones and dead chickens are some of the main types of waste produced by chicken slaughterhouse. From the measurement results, it is estimated that the waste in the form intestinal waste is 5%, 3.5% blood, and dead chickens of 0.5% out of the number of slaughtered chicken per day. However, most of these types of waste such as bones, skin, liver and gizzard are still valuable and required by particular consumers. Furthermore, the characteristics of the wastewater generated from these plants are classified as a high-strength h igh-strength wastewater , where the contaminants’ concentrations have relatively high COD (3102 ± 688 mg/L), suspended solids (SS) (872 ± 178 mg/L), oil & grease (O&G) (375 ± 151 mg/L), nitrogen measured as total Kjeldahl nitrogen (TKN) (186 ± 27 mg (N)/L), and total phosphate (PO4 3-P) (76 ± 36 mg/L). Hence, the discharge of this wastewater without a proper treatment will have realistic damage on the environment and municipal wastewater treatment plants.
Recent studies show that the conventional biological treatment is not capable of removing all compounds to make the discharged water acceptable according to the standards. Consequently, extensive and additional pretreatment often constitutes a basic requirement for final biological purification (Malik L. Hami et al., 2007). Apart from that, the large amount of generated sludge and high demand of energy for aeration will increase the operating cost of the treatment system itself, hence, limiting the potential functions of aerobic technology as the main biological treatment of high-strength slaughterhouse effluents. Some of the main biological treatments such as activated sludge, stabilization ponds and anaerobic reactors are used in poultry slaughterhouse wastewater treatment systems. However, the reduction of mitigating activities of the sludge excess disposal as well as energy saving are some of the benefits offered by anaerobic digestion process to treat slaughterhouse effluents (V. Del Nery et al., 2006). Besides that, Ki Yong Lee et al., (2011) stated that gravitational sedimentation has commonly been utilized to separate activated sludge solids from the treated water. Gravitational sedimentation is considerably cost effective and simple, but due to the low floc density makes this conventional technology’s efficiency an unsatisfactory. In addition, a comprehensive study has proven that wastewater treatment plant suffer from a severe deterioration in their effluent quality due to many problems in terms of sludge rising, pin floc, and gravity clarification (Ki Yong Lee et al., 2011). On the other hand, poultry slaughterhouse wastewater is high in organic matter concentration which consists of nitrogen (N) and phosphorus (P). In such cases like the removal of P and N is done simultaneously in a same reactor, the denitrifiers will compete with P accumulating organisms (PAOs) for rbCOD to release anaerobic P. The competition will result instability of the removal of biological P if the wastewater have insufficient rbCOD. Hence, those phosphorus and nitrogen must be treated separately to prevent the competition. As for nitrogen removal, Sequencing Batch Reactor (SBR) technology can treat these effluents under fill-aerobic-anoxic-settle-discharge sequences in a single reactor basin. The sources of nitrogen are blood, urine and feces while the sources of phosphorus are residual blood, manure, cleaning and sanitizing compounds. SBR also enables both nitrification process under operating conditions (long detention time, sufficient dissolved oxygen concentration and low organic matter concentration) and denitrification process under proper carbon source and anoxic conditions (I.R. de Nardi et al., 2010). In Ireland, the European Commission recommends the on-
site biological treatment to remove organic carbon and nutrients before the wastewater is discharged. Hence, SBR is recommended by The European Commision as the best available techniques (BATs) for slaughterhouse wastewater treatment since SBR is able to remove organic carbon organic carbon and suspended solids from wastewater and have low capital and operational cost. Typical COD, TN and TP removals from slaughterhouse wastewater achieved in SBRs are 95%, 60 – 80% and 40%, respectively. However, SBRs are not able to remove nitrogen (N) as efficiently as to remove COD because slaughterhouse wastewater contains very high TN, with a typical biochemical oxygen demand (BOD5) to TN ratio of 7 – 9:1 (J.P. Li et al., 2008). Phosphorus removal from slaughterhouse wastewater can be achieved by chemical – dissolved-air flotation (DAF) system. An efficient metal use and good process stability can contribute in high quality effluent although the removal of phosphorus can be done by adding chemicals at different stages of wastewater treatment. Moreover, DAF systems have the advantages of high separation efficiency, high operational flexibility and high rate units (I.R. de Nardi et al., 2010). According to the results made by N. T. Manjunath et al., (1999), the float and subnatent from DAF are found to have higher BMP (Biochemical Methane Potential) than that of the raw wastewater which indicates that DAF renders both float and sub-natant with better anaerobic degradability. DAF also reduces waste strength by about 50% (the COD of the float and the sub-natant together is about half the COD of the raw wastewater). On the other hand, by comparing both DAF-UASB and UASB-UASB systems, the DAF-UASB system performs better than the UASB-UASB system. The DAF-UASB system removes more COD of the effluent compared to the UASB-UASB system. The result shows that the DAF system is an effective technology in treating wastewater. However, the DAF itself has its own disadvantages. The instability of DAF system performance is attributed to the variability of the industrial effluent quality characteristics, the inadequacy of the chemical additions, and the full-influent pressurization in the DAF system. Therefore, the improvement on the DAF-effluent quality can be achieved by managing the chemical pretreatment and the DAF operating conditions (Del Nery et al. 2007). Besides that, DAF for secondary clarification has not been widely applied due to the relatively high operating costs for micro-bubble generation. One way to reduce the cost of DAF is applying a flotation tank coupled with a deep aeration tank (Ki Yong Lee et al., 2011)
1.2
PROBLEM STATEMENT
Poultry slaughterhouse is classified as a high-strength wastewater , where the contaminants’ concentrations have relatively high COD (3102 ± 688 mg/L), suspended solids (SS) (872 ± 178 mg/L), oil & grease (O&G) (375 ± 151 mg/L), nitrogen measured as total Kjeldahl nitrogen (TKN) (186 ± 27 mg (N)/L), and total phosphate (PO4 3-P) (76 ± 36 mg/L). These contaminants are there due to the presence of high organic materials such as blood, fat from skin, protein, oil from boiling chickens for feather removal and it will be discharged directly into the water body or drainage system that could lead to environmental pollution. Besides that, animal fats and oils with high 5-day biochemical oxygen demand (BOD5) can reduce the dissolved oxygen status of receiving waters and impact aquatic biota. In addition, if a film of oil and grease forms on the surface in receiving waters, it is unsightly and reduces the natural re-aeration process. Soluble and emulsified FOG can inhibit oxygen and other gas transport processes that are necessary for plants and animals and ultimately result in aquatic ecosystem disruption. Hence, the discharge of this wastewater without a proper treatment will have realistic damage on the environment and municipal wastewater treatment plants. According to the “Study on the Current Issues and Needs for Water Supply and Wastewater Management in Malaysia”, Volume 2 (2015), sewerage treatment systems in the form of individual septic tanks and pour flush systems is introduced and applied in Malaysia during the 1960s. The reduction of direct discharge of sewage pollution can be done by this method. Later, Imhoff tanks were used for treatment as community sewerage systems. During 1970s, biological oxidation ponds were introduced due to the evolution of more expanded treatment. This was to cater for the development of more towns into cities and increased environmental concern. In the late 1970s, due to the increasing population, aerated lagoons were introduced to serve a larger population within a limited land area reserved for oxidation ponds. In the late 1980s and the 1990s saw the accelerated development of fully mechanized systems in the form of biological filters and activated sludge systems. The use of trickling filters and bio filter ponds proved that the biological treatment is able to remove 65% to 85% of Biological Oxygen Demand (BOD) and Suspended Solids (SS). In Ireland, the European Commission recommends the on-site biological treatment to remove organic carbon and nutrients before the wastewater is discharged. If the treated effluent is discharged to water body, it must satisfy other water quality standards. Therefore, SBR is recommended by the EC to be
the best available techniques for slaughterhouse wastewater treatment since SBR is able to remove organic carbon organic carbon and suspended solids from wastewater and have low capital and operational cost. Typical COD, TN and TP removals from slaughterhouse wastewater achieved in SBRs are 95%, 60 – 80% and 40%, respectively. However, SBRs are not able to remove nitrogen (N) as efficiently as to remove COD because slaughterhouse wastewater contains very high TN, with a typical biochemical oxygen demand (BOD5) to TN ratio of 7 – 9:1 (J.P. Li et al., 2008). Despite of the advantages that DAF can offer in treating poultry wastewater, there are still some flaws regarding DAF. The instability of DAF system performance is attributed to the variability of the industrial effluent quality characteristics, the inadequacy of the chemical additions, and the full-influent pressurization in the DAF system (Del Nery et al. 2007). Besides that, DAF for secondary clarification has not been widely applied due to the relatively high operating costs for micro-bubble generation (Ki Yong Lee et al., 2011). However, most of the studies are conducted separately between the integrated DAF and aerated SBR instead of combining them together. Moreover, there is still no report on that focus on the removal of solids and carbonaceous organic by integrated DAF and aerated SBR in order to determine the efficiency for both technologies.
1.3
OBJECTIVES
Objectives of this study are : 1. To determine the physio-chemical characteristic of poultry slaughterhouse wastewater 2. To compare the effluent quality with the Standard B: Industrial effluent, 2009 3. To assess the performance of integrated DAF and aerated SBR in terms of solid and organic removal.
1.4
IMPORTANCE OF RESEARCH
The importance of this research is for analyzing the efficiency and performance of integrated DAF and aerated SBR as the alternatives and additional methods to control as well as decrease the amount of contaminants before discharging the effluent into the water body. DAF and SBR are potentially can increase the rate of organic and carbonaceous solid removal. If DAF and SBR show good results on removing those organic and carbonaceous solid, it can be installed at any poultry slaughterhouse to reduce the amount of contaminants and produce a high quality effluent without making any further damages to the environment.
1.5
SCOPE OF STUDY
The scope of this study mainly focuses on the characterization of influent and effluent sample from the existing poultry slaughterhouse plant and the characteristics to be determined are total suspended solids (TSS), chemical oxygen demand (COD), and biochemical oxygen demand (BOD). The characterization of influent and effluent sample will be obtained from the existing poultry slaughterhouse plant and it will be compared with the Standard B: Industrial Effluent 2009. The values obtained will be compared and it will show the performance of SBR and DAF on the removal of organic and carbonaceous solids.
1.6
LOCATION OF STUDY
CHAPTER 2
LITERATURE REVIEW
2.1
Water Supply and Wastewater Coverage in Malaysia
According to the “Study on the Current Issues and Needs for Water Supply and Wastewater Management in Malaysia”, Volume 2 (2015, treated water in Malaysia is supplied to more than 95% of the population. Water is supplied for 24 hours per day. In Malaysia, water is a state matter, thus the role of the Federal Government is limited. The shortcomings in the provision for safe and affordable water supply services has led the federal government to seek solutions in sharing the responsibility with the state governments in reforming the water services to be selfsustainable. In the year 2005, the Federal Constitution was amended to allow for joint responsibility in water services between the state states in Peninsular Malaysia and Labuan, the Federal Government. Malaysia currently has no single agency in the country entrusted with the overall responsibility for holistic planning and management of water services, wastewater and water resources. However, it has many agencies with overlapping responsibilities at the state and federal levels.
Table : Statistic of Water Supply and Wastewater Cov erage in Malaysia
2.2
Poultry slaughterhouse wastewater (PSW) characteristics
According to Sugito et al., (2016), wastewater produced from a chicken slaughterhouse is one of the sources of environmental pollution. This slaughterhouse industry operates by slaughtering live chicken and processes them into carcass which is prepared for our consumption. The production of the wastewater is either from the washing equipment and facilities or from the process itself. Besides that, a large amount of wastewater generated by poultry slaughterhouse which has a high amount of biodegradable organic matter, suspended and colloidal matter such fats, cellulose and proteins. Apart from that, Sugito et al., (2016), also mentioned that there are chemical-physical waste and microbes contained in the chicken slaughterhouse wastewater. The microbes are such as Bacillussubtilis, Bacillusthuringiensis, and Lysinibacillusfusiform. Blood, feathers, offal (remnants of intestine and cloaca pieces), bones and dead chickens are some of the main types of waste produced by chicken slaughterhouse. From the measurement results, it is estimated that the waste in the form intestinal waste is 5%, 3.5% blood, and dead chickens of 0.5% out of the number of slaughtered chicken per day. However, most of these types of waste such as bones, skin, liver and gizzard are still valuable and required by particular consumers. According to I.R. de Nardi et al., (2010), it is characterized by high concentrations of suspended solids (SS) and organic matter. Some of the principal sources of organic matter are residual blood, chicken fat and feces. Nitrogen content that comes from the blood, urine and feces is mainly as organic nitrogen. Besides that, phosphorus comes from the residual blood, manure, and cleaning and sanitizing compounds is mainly as organic and inorganic phosphates. Based on the research conducted by Ahmed Rahomi Rajab et al, (2016), the PSW was collected from selected poultry slaughterhouse located in Johor (Southern state of Malaysia Peninsular) called AYAMAS Food corporation Sdn. Bhd. This corporation is one of the biggest poultry slaughterhouses in the state and has a production rate of 30,000 – 45,000 birds/day with average wastewater flow rate of 800 m-3 d -1. All samples used in this study were collected from the flow coming from the fixed strainer instrument which is located after feathers removal equipment. Table 2.1 shows the characterization of PSW
Table 2.1 : The PSW characteristics
2.3
Wastewater treatment in Malaysia
Before the country’s independence in 1957, there were no proper sewage systems in Malaysia. In fact, the need for proper sewerage treatment never was a concern to the people during that time due to the low population density and also the very limited urbanized developments. Sewage treatment was mainly by primitive methods such as pit and bucket latrines and over-hanging latrines beside direct discharge into rivers or seas. This was recognized as the most successful model by the World Health Organization, with a minimum of 90% coverage in 1995 (compared to 2.6% in 1970) (Sewerage Services Department 1998). However, for the urban areas, the usage of conventional sewerage approaches had been adopted. The method of treatment during that time could only provide basic primary treatment through the method of sedimentation and digestion. As the world advanced in technology, innovation on the treatment systems and increased involvement from the Government by establishment of Sewerage Service Act 1993, the sewerage systems in Malaysia were gradually improved and developed (“Study on the Current Issues and Needs for Water Supply and Wastewater Management in Malaysia”, Volume 2, 2015)
2.3.1
Septic tank
During 1960s, sewerage treatment systems in the form of individual septic tanks (ISTs) and pour flush systems is introduced and applied in Malaysia. This method helped to reduce the direct discharge of sewage pollution to the environment. As more towns were established, the use of communal septic tanks (CSTs) was introduced to provide for community based sanitation. These CSTs gave similar performance to ISTs but by way of a series of pipes connecting to a row of tanks. CST is clarified as a primary treatment and consisted of two chambers. The effluent enters into the first chamber where solids settle and partially clarified effluent overflows into the second chamber. The sludge then accumulates in the first chamber and requires regular desludging. Additional settlement occurs in the second chamber before the effluent is discharged to the drain.
Figure 1 : Typical Septic Tank
2.3.2
Imhoff tank
Imhoff Tanks were later used for treatment as community sewerage systems. Imhoff tanks constitute 24% or 800 numbers of all sewerage treatment plants in Malaysia and are the second most common form of treatment plant. Imhoff tanks are normally used to service small communities up to a population equivalent of 1,000. They are relatively cheap to install, operate and maintain. However, the Imhoff tanks only partially treat sewage. The effluent from the tank does not meet the environmental requirements of the Department of Environment.
Figure 2 : A typical Imhoff tank
2.3.3
Oxidation pond/ Oxidation Ditch
In the 1970s, the sewerage technology in Malaysia evolved to more expanded treatment in the form of biological oxidation ditch systems. This was to cater for the development of more towns into cities and increased environmental concern which then led to the enactment of the Environmental Quality Act in 1974. The treatment proved to reduce BOD from 200-400 mg/l to 20-100 mg/l. Normally, oxidation ponds consist of at least two constructed ponds. The first pond
is used to reduce the organic material using aerobic digestion while the second pond filters the effluent and reduces the pathogens present. Oxidation ponds require large land areas. The degree of treatment was weather dependent thus causing them to be incapable of achieving a good standard of effluent consistently. A typical plan layout of the oxidation pond as illustrated in Figure below.
Figure : A typical oxidation ditch
2.3.4
Aerated Lagoon
The increased population then caused the introduction of aerated lagoons in the late 1970s in order to serve a larger population within a limited land area reserved for oxidation ponds. The technological advancement allows for enhancement of oxidation pond capacities up to more than five times the original capacities as illustrated in Figure 4 below.
Figure : A typical aerated lagoon
2.3.5
Biological Filters
The late 1980s and the 1990s saw the accelerated development of fully mechanized systems in the form of biological filters and activated sludge systems due to enactment of Environmental Quality Regulations, 1979. The use of trickling filters and bio filter ponds proved that the biological treatment is able to remove 65% to 85% of Biological Oxygen Demand (BOD) and Suspended Solids (SS).
Figure : A typical trickling filter
2.4
Dissolved Air Floatation (DAF) System
According to I.R. de Nardi, T.P. Fuzi and V. Del Nery (2007), despite of the high concentrations of SS and organic matter, the slaughterhouse wastewater’s characteristics make it applicable for biological treatment applications. However, since slaughterhouse wastewater consists of high SS and organic matter rates, as well as oil and grease (O&G), an efficient separator is necessary prior to the use of biological process in order to prevent process instability. Due to separation problem, environmental engineers have come up with an innovation called the Dissolved Air Flotation (DAF) system. The DAF system has been widely applied in the primary treatment of food industry wastewater to separate suspended or fatty particles from the liquid. In order to control the DAF system, there are some process variables that should be considered. The process variables are the effluent quality requirements, hydraulic structure load, and saturation pressure, recycle rate, air/solid (A/S) ratio, pretreatment process and influent characteristics. According to I.R. de Nardi et al., (2010), chemical DAF system can achieve phosphorus removal from slaughterhouse wastewater. Although the chemical can added at different stages of wastewater
treatment for instance, primary clarifier effluent, raw wastewater, biological units or after the biological treatment effluent, an efficient metal use and a good process stability will produced a high quality effluent. The advantages of using chemical DAF system are high operational flexibility, high separation efficiency and high-rate units. According to V. Del Nery et al., (2006), the air saturator and the floatation tank operating parameters in DAF are stated as in Table 2.2 and 2.3
Table 2.2 : The air saturator operating parameters Air Saturator Volume (m3)
4.8
Saturation pressure (kPa) A/S ratio
200-400 0.013
Table 2.3 : The air saturator operating parameters Floatation tank Depth (m)
2.5
Diameter (m)
6.4
Surface area (m2)
32
Volume (m3)
80
DAF-effluent recycling
None
Figure : The conventional DAF unit with water recycle to the saturator
2.5
Sequencing Batch Reactor (SBR) System
According to W. J. Ng et al., (1993), an SBR system may consist of one or more reactors. Every reactor will be filled in turn for a discrete period of time and operated in a batch treatment mode. Then, allow the mixed liquor to settle and the clarified supernatant is drawn. After the remaining reactors in SBR system have been filled, the reactor will be refilled again. Usually, every reactor in an SBR system will undergoes one or more cycles per day. A typical cycle consists of five periods that are namely as fill, react, settle, decant and idle. These time sequential operations have been made easy with the advances made in valves, timing and switching technology. Reactors operated in the SBR may give gradual equalization, idle sedimentation, marked reductions in system volume and potentially allowing much better control over the effluent quality. Besides that, J.P. Li et al., (2008) stated that SBR is recommended by The European Commision to be amongst the best available techniques (BATs) for slaughterhouse wastewater treatment since it potentially can remove organic carbon, nutrients and SS from wastewater as well as having a low capital and operational costs. According to I.R. de Nardi et al., (2010), effluents with high ammonia and low organic matter concentration will enable the use of
biological nitrogen removal process. Hence, SBR technology can treat these effluents under fillaerobic-anoxic-settle-discharge sequences in a single reactor basin. Both nitrification process under operating conditions such as low organic matter concentrations, sufficient dissolved oxygen concentrations and long sludge retention time, and the denitrification process under suitable anoxic conditions and carbon source. The Table below shows the SBR operating conditions according to I.R. de Nardi et al., (2010)
Table 2.4 : SBR operating conditions
2.6
Fundamentals process of Sequencing Batch Reactor
According to W. J. Ng et al., (1993), every reactor in an SBR system will undergoes one or more cycles per day. A typical cycle consists of five periods that are namely as fill, react, settle, decant and idle.
2.6.1
Fill period
According to New England Interstate Water Pollution Control Commission (2005), the basin receives influent wastewater during this phase. The influent p rovides food for the microbes in the activated sludge thus creating an environment for biochemical reaction to take place. During the fill phase, mixing and aeration can be varied to create the following three different scenarios: Static Fill – Influent wastewater is entering the tank and there will be no mixing or aeration during this static fill. Static fill is used during the initial start-up phase of a facility, at plants that do not need to nitrify or denitrify, and during low flow periods to save power. Because the mixers and aerators remain off, this scenario has an energy-savings component. Mixed Fill – Under a mixed-fill scenario, mechanical mixers are active, but the aerators remain off. The mixing action produces a uniform blend of influent wastewater and biomass. Because there is no aeration, an anoxic condition is present, which promotes denitrification. Anaerobic conditions can also be achieved during the mixed-fill phase. Under anaerobic conditions the biomass undergoes a release of phosphorous. This release is reabsorbed by the biomass once aerobic conditions are reestablished. This phosphorous release will not happen with anoxic conditions.
Aerated Fill – Under an aerated-fill scenario, both the aerators and the mechanical mixing unit are activated. The contents of the basin are aerated to convert the anoxic or anaerobic zone over to an aerobic zone. No adjustments to the aerated-fill cycle are needed to reduce organics and achieve nitrification. However, to achieve denitrification, it is necessary to switch the oxygen off to promote anoxic conditions for denitrification. By switching the oxygen on and off during this phase with the blowers, oxic and anoxic conditions are created, allowing for nitrification and denitrification. Dissolved oxygen (DO) should be monitored during this phase so it does not go over 0.2 mg/L. This ensures that an anoxic condition will occur during the idle phase.
2.6.2
React period
New England Interstate Water Pollution Control Commission (2005), stated that this phase allows for further reduction of wastewater parameters. During this phase, no wastewater enters the basin and the mechanical mixing and aeration units are on. Because there are no additional volume and organic loadings, the rate of organic removal increases dramatically. Most of the carbonaceous BOD removal occurs in the react phase. Further nitrification occurs by allowing the mixing and aeration to continue the majority of de-nitrification takes place in the mixed-fill phase. The phosphorus released during mixed fill, plus some additional phosphorus, is taken up during the react phase.
2.6.3
Settle period
During the settle period, activated sludge is allowed to settle under quiescent conditions which are no flow enters the basin and no aeration or mixing will take place. The activated sludge will settle as a flocculent mass thus forming a distinctive interface with the clear supernatant. If the solids are not settle rapidly, some sludge will be drawn off during the subsequent decant phase. Hence, it will degrade the effluent quality. (New England Interstate Water Pollution Control Commission., 2005)
2.6.4
Decant period
During this phase, a decanter is used to remove the clear supernatant effluent. Once the settle phase is complete, a signal is sent to the decanter to initiate the opening of an effluent-discharge valve. There are floating and fixed-arm decanters. Floating decanters maintain the inlet orifice slightly below the water surface to minimize the removal of solids in the effluent removed during the decant phase. Floating decanters offer the operator flexibility to vary fill and draw volumes. Fixed-arm decanters are less expensive and can be designed to allow the operator to lower or raise the level of the decanter. It is optimal that the decanted volume is the same as the volume that enters the basin during the fill phase. It is also important that no surface foam or scum is decanted. The vertical distance from the decanter to the bottom of the tank should be maximized to avoid disturbing the settled biomass (New England Interstate Water Pollution Control Commission., 2005).
2.6.5
Idle period
The idle period occurs between decant and fill phases. The time may vary depending on the influent flow rate and the operating strategy. A small amount of activated sludge at the bottom of SBR will be pumped out during this period. (New England Interstate Water Pollution Control Commission., 2005).
CHAPTER 3
METHODOLOGY
3.1
Sampling
According to Sugito et al., (2016), the sample used is the slaughterhouse waste water after the feather plucking process is completed. The wastewater is taken as the results from the second rinsing process to drain the blood. However, the wastewater from the first washing was not taken since it was considered as a shot waste and chicken feathers have not been plucked yet which means that the chicken are still being soaked in hot water. From the settling tank, wastewater samples are collected and filled in the plastic container which volumetric size of 20 L. The objective of sampling is to collect a portion of material small enough in volume to be transported conveniently and yet large enough for analytical purposes while still accurately representing the material being sampled. This objective implies that the relative proportions or concentrations of all pertinent components will be the same in the samples as in the material being sampled, and that the sample will be handled in such a way that no significant changes in composition occur before the tests are made.
3.2
Analytical Methods
In terms of monitoring, D.P. Cassidy and E. Belia (2005) stated that, the samples taken are analyzed using the methods in Standard Methods for the Examination of Water and Wastewater. According to Seswoya, R et al., (2012), the wastewater characteristics were done for pH, dissolved oxygen, temperature, Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD) and Total Solids (TS). All parameters are analyzed in accordance with the Standard Methods of the Examination of Water and Wastewater. The automatic meter (YSI 6600) was used to measure pH, dissolved oxygen and temperature. For COD measurement, Hach DR/4000 Spectrophotometer, is used according to Method 8000 (Digestion Method). The TS
measurement is following the Standard Methods for the Examination of Water and Waste Water using the Method 2540A-E. The measurement of BOD is done by using Partition-Gravitimetric Method according to Method 2540 A-E.
Parameter
BOD5
Method
Reference
BOD apparatus : APHA 5520B (Partition-
Roslinda Bt Seswoya et al., 2006
Gravitimetric Method)
COD
COD
apparatus
:
Spectrophotometer,
Hach
DR/4000
Method
Seswoya, R et al., 2012
8000
(Digestion Method) TS
3.2.1
TS apparatus : Method 2540A-E
Seswoya, R et al., 2012
Biochemical Oxygen Demand (BOD)
According to Roslinda Bt Seswoya et al., (2006), the BOD measurement is done according to Method 5220 B (Partition-Gravitimetric Method) by Standard Methods for the Examination of Water and Wastewater. Firstly, mark the sample bottle at the water meniscus or weigh the bottle when the sample is brought into the laboratory, for later determination of sample volume. Acidify the sample with either 1:1 HCl or 1:1 H2SO4 to pH 2 or lower (5 mL is enough for 1L sample) if the samples are not acidified previously. Next, transfer sample to a separator funnel by using a liquid funnel. Rinse the sample bottle carefully with 30 mL extracting solvent and solvent washings is added to the separator funnel. Vigorously shake for 2 minutes and let the layers to separate. An aqueous layer and a small amount of organic layer are drained into original sample container. Then, drain the solvent layer through a funnel containing a filter paper and 10 grams of Na2SO4 (both which have solvent-rinsed) into a clean, tared distilling flask. If an emulsion of more than about 5 mL exists and a clear solvent layer cannot be obtained, the emulsion and solvent layers are drained into a glass centrifuge tube. The tube is centrifuged for 5 minutes at approximately 2400 rpm.
The centrifuged material is transferred into an appropriate separator funnel. Drain the solvent layer through a funnel with a filter paper and 10 grams of Na2SO4 (both have been pre-rinsed, into a clean, tared distilling flask). Recombine aqueous layers and any remaining emulsion or solids in separator funnel. For samples with <5 mL of emulsion, drain only the clear solvent through a funnel with pre-moistened filter paper and 10 g Na2SO4. Recombine aqueous layers and any remaining emulsion or solids in separator funnel. Extract twice more with 30 mL solvent each time, but first rinse sample container with each solvent portion. Repeat centrifugation step if emulsion persists in subsequent extraction steps. Combine extracts in tared distilling flask, and include in flask a final rinsing of filter and Na2SO4 with an additional 10 to 20 mL solvent. Distill solvent from flask in a water bath at 85°C for either solvent system. To maximize solvent recovery, fit distillation flask with a distillation adapter equipped with a drip tip and collect solvent in an ice-bath-cooled receiver. When visible solvent condensation stops, remove flask from water bath. Cover water bath and dry flasks on top of cover, with water bath still at 85°C, for 15 min. Draw air through flask with an applied vacuum for the final 1 min. Cool in desiccator for at least 30 min and weigh. To determine initial sample volume, either fill sample bottle to mark with water and then pour water into a 1-L graduated cylinder, or weigh empty container and cap and calculate the sample volume by difference from the initial weight (assuming a sample density of 1.00).
3.2.2
Chemical Oxygen Demand (COD)
The COD measurement is done by using COD vial (TNT plus 822- range: 20-1500 mg/L COD) Hach DR/4000 Spectrophotometer according to Method 8000 (Digestion Method) (Seswoya, R et al., 2012) Put 100 mL of sample in a blender. The sample is blended for 30 seconds or until homogenized. For samples with large amounts of solids, increase the homogenization time. If the sample does not contain suspended solids, go to step 3. For the 200-15,000 mg/L range or to improve accuracy and reproducibility of the other ranges, pour the homogenized sample into a 250‑mL beaker and gently stir with a magnetic stir plate. Set the DRB200 Reactor power to on. Preheat to 150 °C. Refer to the DRB200 User Manual for selecting preprogrammed temperature applications.
For the preparation of sample, remove the cap from a vial for the selected range. Hold the vial at an angle of 45 degrees. Use a clean pipet to add 2.00 mL of sample to the vial. For 250 – 15,000 mg/L vials: Use a TenSette Pipet to add 0.20 mL of sample to the vial. For the preparation of the blank, remove the cap from a second vial for the selected range. Hold the vial at an angle of 45 degrees. Use a clean pipet to add 2.00 mL of deionized water to the vial. For 250 – 15,000 mg/L vials: Use a TenSette Pipet to add 0.20 mL of deionized water to the vial. Close the vials tightly. Rinse the vials with water and wipe with a clean paper towel. Hold the vials by the cap, over a sink. Invert gently several times to mix. The vials are tend to be very hot hence, precaution steps must be taken. Hold the vials by the cap, over a sink. Invert gently several times to mix. Heat the vials for 2 hours. Set the reactor power to off. Let the vials cool in the reactor for approximately 20 minutes to 120 °C or less. Invert each vial several times while it is still warm. Put the vials in a tube rack to cool to room temperature. At last, spectrophotometer DR 6000 is used to take COD reading.
3.2.3
TS (Total Solid)
The Total Solid (TS) were measured according to Method 2540A-E (Seswoya, R et al., 2012).
3.3
Statistical analysis
Analysis of variance (ANOVA) was used for graphical analyses of the data to obtain the interaction between the independent variables and the responses. The quality of the fit polynomial model was expressed by R2 and Radj 2 (coefficient of determination). The statistical significance of models was checked by the F-test. Normal probability plot of studentized residuals, predicted vs. actual values plots and three dimensional plots were obtained for color removal, BOD removal, COD removal, and pH. Furthermore, the optimum region was identified based on the process parameters in the overlay plot.
