Industrial solid waste sampling technology (2)

3.

(1) Determination of the number of duplicate samples and sampling volume

Refer to Table 2-1 for the relationship between the minimum number of samples collected for industrial solid waste and the batch quality of solid waste

Table 2-1 Batch size and minimum number of copies

Note: The bulk mass of solid waste is calculated in t, and the bulk mass of liquid waste is calculated in 1000L

Generally speaking, the amount of incremental sample depends on the upper limit of the particle size of the solid waste.

Q≥Kd ^a 

In the formula, Q—the lowest mass that the sample volume should be collected, kg;

d—The diameter of the largest particle size in the waste, mm;

K-reduction factor, representing the degree of unevenness of the waste, the more uneven the waste, the greater the K value, which can be determined experimentally by the statistical error method, and sometimes specified by the competent authority based on experience;

a——The empirical constant, which depends on the uniformity and fragility of the waste

Generally, K=0.

(2) Sampling method

There are many sampling methods for industrial solid waste, and the sampler should combine the method requirements and collect representative samples according to the actual situation of the site and local conditions

1.

The effectiveness of collecting samples by individuals who are very familiar with the industrial solid waste being collected depends entirely on the knowledge of the person who sampled and the cognition of the object being sampled

2.

Suitable for small storage thickness, industrial solid waste in transportation, and liquid industrial waste in shallow ponds (pits, ponds).

Figure 2-1 Simple random sampling method

3.

It is suitable for storing higher solid industrial solid wastes and liquid industrial solid wastes stored in deeper ponds (pits, ponds).

4.

Suitable industrial solid waste in the form of transport belts, pipes and the like is continuously discharged
.
In the moving process where a batch of waste is continuously discharged in the form of conveyor belts, pipelines, etc.
, incremental samples are taken at a certain quality or time interval.
The interval between incremental samples can be based on the number of incremental samples specified in Table 2-1 and the actual batch according to the formula (2) Calculation:

In the formula, T—sample mass interval, t;

Q-batch size, t;

The number of incremental samples specified in n—2-1;

G—discharge volume per hour, t/h;

T'-like time interval, min
.

When taking the first incremental sample, it cannot start at the beginning of the first interval, but can be randomly determined within the first interval; when sampling on the conveyor belt or at the drop, the full cross-section of the waste stream should be intercepted
.

5.
Two-stage sampling method

It is suitable for sampling wastes contained in many vehicles, barrels, boxes, bags and other containers
.
When a batch of waste is contained in many containers such as vehicles, barrels, boxes, bags, etc.
, since the containers are relatively scattered, sampling should be carried out in stages
.

In the first stage, n ₁ containers are randomly selected from the total number of waste containers N _0.
When N ₀ ≤6, n1=N0; when N ₀＞6, n _{1 is} calculated according to formula (3):

The second stage: take n ₂ incremental samples from each of n ₁ containers , n ₂ ≥3 is recommended (at least 3 incremental samples are randomly taken from the upper, middle, and lower sides of each container), the upper part is equivalent to the lower surface At 1/6 of the total depth, the middle one surface is equivalent to 1/2 of the total depth, and the lower part—the surface is equivalent to 5/6 of the total depth (see Figure 2-3) .

Figure 2-3 Schematic diagram of container layered sampling

In addition to the above-mentioned sampling methods, other sampling methods that can collect representative samples are also suitable for industrial solid waste sampling
.

Related links: Industrial solid waste sampling technology (1)