Pengolahan Limbah - Karakteristik Limbah Cair (Part 3/4)

Summary

The video explains the chemical characteristics of wastewater, focusing on Biochemical Oxygen Demand (BOD) and Chemical Oxygen Demand (COD). BOD measures the oxygen required for the microbial breakdown of organic matter in water, while COD assesses the chemical oxidation of pollutants. The script details testing methods, including the Winkler method for BOD and the use of potassium dichromate for COD. Regulatory standards for BOD and COD in industrial wastewater are also discussed, emphasizing the importance of oxygen levels for aquatic life and environmental health.

Takeaways

• 😀 BOD (Biochemical Oxygen Demand) measures the amount of oxygen needed to decompose organic matter in water, which is crucial for assessing water quality.
• 😀 Oxygen is essential for the survival of aquatic life, including fish and microorganisms, which rely on it to break down organic materials in water.
• 😀 BOD indicates the level of pollution in water by showing how much oxygen is consumed by microorganisms during the decomposition of organic compounds.
• 😀 A high BOD value indicates high levels of organic pollution in water, which can lead to oxygen depletion, harming aquatic life.
• 😀 COD (Chemical Oxygen Demand) measures the oxygen required to oxidize organic pollutants chemically, using an oxidizing agent like potassium dichromate.
• 😀 Both BOD and COD tests help assess the pollution levels in wastewater, with BOD focusing on biological degradation and COD on chemical degradation.
• 😀 The Winkler method is used to measure dissolved oxygen in water, with titration steps involving manganese chloride and sodium hydroxide to determine oxygen levels.
• 😀 In the BOD test, a water sample is incubated for five days to allow microorganisms to decompose organic material and reduce oxygen levels, which is then measured.
• 😀 COD testing involves adding potassium dichromate and heating the sample in a reflux apparatus, followed by titration to measure the amount of oxygen used in the reaction.
• 😀 The standard quality for BOD in industrial wastewater is not to exceed 50 mg/l, and for COD, it should be less than 100 mg/l according to environmental regulations.

Q & A

What are the five main chemical characteristics used to analyze liquid waste?

The five main chemical characteristics of liquid waste discussed in the script are BOD (Biological Oxygen Demand), COD (Chemical Oxygen Demand), water hardness, heavy metal concentration, and the content of organic matter.

Why is oxygen important for aquatic life, especially in polluted water?

Oxygen is crucial for aquatic life because many organisms, such as fish and microorganisms, rely on dissolved oxygen to survive. Polluted water often lacks sufficient oxygen due to the decomposition of organic matter, leading to the death of aquatic organisms.

What does the BOD (Biological Oxygen Demand) test measure?

The BOD test measures the amount of oxygen required by microorganisms to decompose organic matter in water. It indicates the level of pollution in a water sample, with higher BOD values suggesting more organic material and poorer water quality.

How is BOD typically measured in a laboratory setting?

BOD is measured by first determining the dissolved oxygen (DO) level in a water sample. The sample is then incubated for five days at 20°C, after which the DO level is measured again. The difference in DO values indicates the BOD.

What is the standard BOD limit for industrial wastewater, according to Indonesian regulations?

According to Indonesian regulations (Permen LH No. 5/2010), the standard BOD limit for industrial wastewater is 50 mg/L.

What does COD (Chemical Oxygen Demand) measure, and how is it different from BOD?

COD measures the total amount of oxygen required to chemically oxidize organic and inorganic substances in water. Unlike BOD, which only measures oxygen demand from biological processes, COD includes oxygen demand from all substances that can be oxidized chemically, including non-biodegradable pollutants.

What method is used to measure COD in a laboratory, and why is it more complex than measuring BOD?

COD is measured using a chemical oxidation process with potassium dichromate (K2Cr2O7) in an acidic environment. The process is more complex than BOD measurement because it involves heating, using a reflux apparatus, and titration to determine oxygen consumption.

What is the acceptable COD limit for industrial wastewater, and why is this limit important?

The acceptable COD limit for industrial wastewater is 100 mg/L. This limit ensures that industrial discharges do not contain excessive organic material that could harm the environment, reduce oxygen levels in water, and negatively affect aquatic life.

How does the Winkler method relate to BOD measurement?

The Winkler method is used to measure dissolved oxygen (DO) in water samples, which is essential for calculating BOD. In this method, manganese chloride (MnCl2) reacts with oxygen in the sample, forming manganese oxide (MnO2), which is then titrated to determine the oxygen content.

What role do microorganisms play in the process of measuring BOD?

Microorganisms in the water sample consume oxygen while decomposing organic material. The BOD test relies on this biological activity to determine the amount of oxygen consumed over a period of time (usually five days), reflecting the level of organic pollution in the water.