Characterization of kitchen wastes for phosphorus recovery

Lucita Felicity Anak Ayut, (2015) Characterization of kitchen wastes for phosphorus recovery. Universiti Malaysia Sabah. (Unpublished)

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Abstract

Kitchen waste is one of the municipal wastes which produced everyday by individuals, hence it can be found abundantly in nature. It has high organic content and can cause various problems to environment. Phosphorus, a limited and non-renewable mineral source, is an essential element in our daily life especially for agricultural industry. Despite its importance and scarcity, the excess phosphorus applied into soil as fertilizer can be leached into water bodies and caused a phenomenon called eutrophication. Therefore, a study was conducted to determine the physical and chemical characteristics of kitchen wastes for phosphorus recovery, via anaerobic digestion (AD). This study has been carried out by using two types of sample liquids namely Kitchen Wastes Liquid (KWL) which obtained from raw sample and Kitchen Wastes Digested Liquor (KWDL), obtained from digested sample of 15 days digestion period. The results showed that the pH of kitchen wastes used in this study were in the range of 6.0 - 7.0. Total solids (TS) and volatile solids (VS) for raw sample was high which were 42.9% and 94.29%, respectively. This was due to the addition of distilled water and this procedure was carried out in order to determine the amount of organic loadings in the sample. If the %TS and %VS reached ~20% and ~90%, respectively; it indicates that the organic content in the sample is higher, therefore the sample is considered suitable for an anaerobic digestion. For the AD samples, TS and VS were degraded from AD sample Day 1 until AD sample Day 15; where for AD sample Day 1, the %TS and %VS were 6.34% and 40.96%, respectively; while for AD sample Day 15, the %TS and %VS were 2.79% and 17.78%, respectively. The concentration of magnesium (Mg²⁺) increased from KWL to KWDL, which is 45.73 mg/L for KWL and 114.00 mg/L for KWDL due to the solubilisation of Mg Mg²⁺ during the AD process. The concentration of ammonium (NH₄⁺), on the other hand, decreased from 192.0589 mgN/L in KWL to 73.8688 mgN/L in KWDL which might due to the loss of nitrogen to biogas in the form of ammonia, NH3 gas. The concentration of phosphate (PO4³⁻) which is the most vital nutrient in this study, increased from 509.18 mg/L in KWL to 554.04 mg/L in KWDL. The amount of PO4³⁻ that increased was not contented enough, as the AD process was expected to release huge amount of PO4³⁻. This might due to the loss of PO4³⁻ ions during filtration and sample storage. The amount of phosphorus (P) recovered in this study was determined theoretically by assuming in terms of struvite formation, the weight of VS degraded during the AD process and the concentration of PO4³⁻ in raw sample and digested sample; which has gave values of 0.46 g/L struvite in KWL and 1.00 g/L struvite in KWDL, 4.31 g/g of P from VS degradation and 8.8% P from PO4³⁻ ions that formed in raw and digested sample, respectively. These significant values of P recovery shows that anaerobic digestion is a reliable method for recovering P from organic wastes such as kitchen wastes, garden wastes, palm oil mill effluent (POME) and empty fruit bunches (EFB). Kitchen waste is one of the municipal wastes which produced everyday by individuals, hence it can be found abundantly in nature. It has high organic content and can cause various problems to environment. Phosphorus, a limited and non-renewable mineral source, is an essential element in our daily life especially for agricultural industry. Despite its importance and scarcity, the excess phosphorus applied into soil as fertilizer can be leached into water bodies and caused a phenomenon called eutrophication. Therefore, a study was conducted to determine the physical and chemical characteristics of kitchen wastes for phosphorus recovery, via anaerobic digestion (AD). This study has been carried out by using two types of sample liquids namely Kitchen Wastes Liquid (KWL) which obtained from raw sample and Kitchen Wastes Digested Liquor (KWDL), obtained from digested sample of 15 days digestion period. The results showed that the pH of kitchen wastes used in this study were in the range of 6.0 - 7.0. Total solids (TS) and volatile solids (VS) for raw sample was high which were 42.9% and 94.29%, respectively. This was due to the addition of distilled water and this procedure was carried out in order to determine the amount of organic loadings in the sample. If the %TS and %VS reached ~20% and ~90%, respectively; it indicates that the organic content in the sample is higher, therefore the sample is considered suitable for an anaerobic digestion. For the AD samples, TS and VS were degraded from AD sample Day 1 until AD sample Day 15; where for AD sample Day 1, the %TS and %VS were 6.34% and 40.96%, respectively; while for AD sample Day 15, the %TS and %VS were 2.79% and 17.78%, respectively. The concentration of magnesium (Mg²⁺) increased from KWL to KWDL, which is 45.73 mg/L for KWL and 114.00 mg/L for KWDL due to the solubilisation of Mg Mg²⁺ during the AD process. The concentration of ammonium (NH₄⁺), on the other hand, decreased from 192.0589 mgN/L in KWL to 73.8688 mgN/L in KWDL which might due to the loss of nitrogen to biogas in the form of ammonia, NH3 gas. The concentration of phosphate (PO4³⁻) which is the most vital nutrient in this study, increased from 509.18 mg/L in KWL to 554.04 mg/L in KWDL. The amount of PO4³⁻ that increased was not contented enough, as the AD process was expected to release huge amount of PO4³⁻. This might due to the loss of PO4³⁻ ions during filtration and sample storage. The amount of phosphorus (P) recovered in this study was determined theoretically by assuming in terms of struvite formation, the weight of VS degraded during the AD process and the concentration of PO4³⁻ in raw sample and digested sample; which has gave values of 0.46 g/L struvite in KWL and 1.00 g/L struvite in KWDL, 4.31 g/g of P from VS degradation and 8.8% P from PO4³⁻ ions that formed in raw and digested sample, respectively. These significant values of P recovery shows that anaerobic digestion is a reliable method for recovering P from organic wastes such as kitchen wastes, garden wastes, palm oil mill effluent (POME) and empty fruit bunches (EFB).

Item Type: Academic Exercise
Uncontrolled Keywords: kitchen wastes, phosphorus recovery, anaerobic digestion
Subjects: T Technology > TD Environmental technology. Sanitary engineering
Divisions: FACULTY > Faculty of Science and Natural Resources
Depositing User: Munira
Date Deposited: 29 Jan 2018 14:59
Last Modified: 29 Jan 2018 14:59
URI: http://eprints.ums.edu.my/id/eprint/18519

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