Professional BOD, COD, k-rate calculations with Thai PCD effluent standards compliance checking. Built for environmental engineers.
Reference values from the Pollution Control Department (PCD)
Industrial Effluent Type A
Strictest standards for industrial facilities
Industrial Effluent Type B
General industrial effluent standards (relaxed)
Community Wastewater
Municipal/community wastewater treatment
BOD5 = (D1 - D2) x DF
DF = Bottle Volume / Sample Volume
BODu = BOD5 / (1 - e^(-k*5))
k = first-order rate constant
COD = (A - B) x N x 8000 / V
A=blank, B=sample, N=normality
>0.5: Easily biodegradable
0.3-0.5: Moderate
<0.3: Difficult
kT = k20 x theta^(T-20)
theta = 1.047 (typical)
E = (Cin - Cout) / Cin x 100%
Cin=influent, Cout=effluent
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BOD5, COD, k-rate, loading, efficiency, and more
Standard Methods for Water and Wastewater analysis
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BOD measures the amount of oxygen consumed by microorganisms to decompose organic matter in water over 5 days at 20C. Higher BOD indicates more organic pollution. BOD5 is the standard 5-day test used worldwide.
COD measures the total quantity of oxygen required to oxidize all organic material in water using a strong chemical oxidant (dichromate). COD is always higher than BOD because it includes non-biodegradable organics.
The BOD/COD ratio indicates how biodegradable the wastewater is. Ratio >0.5 means easily biodegradable (suitable for biological treatment). Ratio <0.3 means difficult to biodegrade (may need chemical/physical treatment first).
Thai effluent standards are set by the Pollution Control Department (PCD). Type A is strictest (industrial estates), Type B is general industry, and Type C is for community/municipal wastewater. All discharges must comply with these limits.
The k-rate (deoxygenation rate constant) describes how fast organic matter is decomposed. Typical values range from 0.1-0.3/day. Higher k means faster decomposition. It varies with temperature, waste type, and microbial activity.
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