Population equivalent

Per capita flow varies from <378 L/d (2) for a residential community to >1134 L/d for highly industrialized areas. The concept of population equivalent is used for evaluating industrial waste contributions to sewage. It is appHed when planning for hydrauhc and BOD loadings. 

WWTP Population equivalent Flow (m" h- ) Receiving river water Type of wastewater treated Hydraulic retention time Primary treatment Secondary treatment... 

TABLE 5.2 Livestock and Poultry Manures Generated in the United States and Their Human Population Equivalent"... 

Livestock/Poultry Population (10 ) Manure production (dry kg/head-day) (10 dry t/year) Human population equivalent Factor (10 ) ... 

Commercial broilers had the highest population, about 7 billion, and they produced the second largest amount of manure cattle, which had a population of about 100 million, produced the largest amount. No differentiation was made in this assessment between dairy and beef cattle. The daily production rate per head of dry manure solids used was the arithmetic average of dairy cattle and beef cattle, since the dairy-to-beef cattle ratio of the reported manure production rates is about 1.45 (Stanford Research Institute, 1976). Some assessments indicate that the ratio of productivities is 3.1 (Jaycor, 1990). The effects of daily manure production per animal are evident as shown in Table 5.2. When published waste production factors are used for conversion of the animal populations to human equivalents in terms of solid waste generation as shown in the table, the total human population equivalent of these animals is estimated at almost 3 billion people. This is approximately 12 times the U.S. population in the mid-1990s, a ratio considerably less than reported in 1968, when it was estimated to be 20 times that of the human population (American Chemical Society, 1969). But the latter ratio included liquid wastes as well. The ratio of total animal excreta to total municipal biosolids generation calculated here, both of which exclude liquid wastes, is about 36 on a mass basis (307.1 dry t/8.6 million dry t). 

For orientation, a comparison of the scope of pollution of industrial wastewaters with sewage waters (e.g. for the calculation of loading the treatment units in the common wastewater treatment plant) involving the so-called population equivalent, or equivalent number of inhabitants has been used. Its calculation is based on the value of pollution in BOD5 per capita per day (54 or 60 g). In the case of industrial wastewaters the average value... 

Thus, the population equivalent is the quantity of pollution expressed in the corresponding units of the given type of pollution which is the same as the pollution of this type produced daily by one person. 

In addition to BOD5 other criteria can also be used for the calculation of population equivalents, for example, COD or the content of suspended solids, which can be more important for some industrial wastewaters. The population equivalent usually refers to the specific unit of raw material or product. 

For wastewaters polluted mainly by undissolved inorganic substances (e.g. from metallurgical and mining operations) the population equivalents can be calculated in such a way that the value of specific production of undissolved substances per capita per day (90 g) is substituted into the above formula. 

The population equivalent is a conventional unit which does not express all the properties of industrial wastewaters. Moreover, their values vary at each change in the production technology which has an impact on the composition of wastewaters (e.g. changes such as saving of water, introduction of recirculation, etc.). The quoted values of population equivalents differ, therefore, quite considerably in the literature. 

In addition to the population equivalent, the term coefficient of pollution has also been introduced, which is a measure of pollution and harmfulness of industrial wastewaters and expresses how many times are the wastewaters in question more polluted and harmful than sewage waters. 

Rom DM, Hwang E (1996) Testing for individual and population equivalence based on the proportion of similar responses [see comments]. Statistics in Medicine 15 1489-1505. [Comment in Statistics in Medicine 16(11) 1303-1306 (1997)]. 

PE = population equivalent (i.e., organic load due to a member of the population over 24 h). 

MBR technology is now considered a mature technology since it has been widely implemented for the treatment of municipal and industrial wastewater. MBR technology is an attractive solution for medium size plants, with a population equivalent of 5000-100,000. However, MBR plants still remain an expensive solution for most decentralized schemes. Despite the development of MBR technology, less than 1% of Europe s population was serviced by MBR in 2011 and it is unlikely that this technology will extensively replace CAS in the near future (Lesjean et al, 2011). 

Similarly, the chain length distribution of dead polymer population (equivalently, that of the total polymer) can be derived based on the mass balance of... 

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