Organic loading in a trickling filter is measured in kg/hectare-meter/day.

Explanation:

Trickling filters are a type of biological wastewater treatment system that use a bed of porous media, such as rock or plastic, to support a biofilm of bacteria. These bacteria break down organic matter in the wastewater, converting it into carbon dioxide, water, and biomass. The efficiency of a trickling filter depends on the organic loading, which is the amount of organic matter applied to the filter per unit of time.

The organic loading in a trickling filter is measured in kg/hectare-meter/day. This unit represents the amount of organic matter (in kilograms) applied to a hectare of filter media (surface area) over a meter depth, per day.

To understand why this unit is used, let's break it down:

1. Kilograms (kg): This unit represents the mass of the organic matter. It is a common unit of measurement for substances in engineering and sciences.

2. Hectare (ha): This unit represents the area of the filter media. A hectare is equal to 10,000 square meters. It is a commonly used unit for large areas, such as agricultural fields or wastewater treatment facilities.

3. Meter (m): This unit represents the depth of the filter media. It is the distance from the surface of the media to the bottom. The depth is important because it determines the volume of the filter bed.

4. Day: This unit represents the time period over which the organic loading is measured. It is commonly used for operational purposes and allows for easy comparison and tracking of the organic loading rate.

By combining these units, we can calculate the amount of organic matter applied to the trickling filter per unit of time, taking into account the area and depth of the filter bed. This measurement helps operators and engineers monitor and optimize the performance of the trickling filter by ensuring that the organic loading is within the system's design capacity.