Trends in Municipal Wastewater Loads 19002000

Population Served. Figure 23.2 displays the type of sewage treatment received over time by the population in the middle and lower Hudson basins. During the course of the twentieth century, the total population served by municipal wastewater facilities has more than doubled from 3.4 million in 1900 to 8.5 million by 2000. This increase reflects the growth of the population of the New York and New Jersey metropolitan region and, beginning in about 1880, the increasing proportion of the population in the metropolitan drainage basin that was connected to urban sewerage collection systems (see Suszkowski, 1990). Reflecting the movement of people to the suburbs following WWII, the sewered population served by wastewater facilities in the middle Hudson basin rose from 10 percent of the total in the mid-1950s to 18 percent by 2000 (Fig. 23.3a).

The population served by facilities discharging untreated sewage steadilyincreased during the period from 1900 to the 1930s (Fig. 23.2). In the middle Hudson, raw sewage was discharged by 0.4 million people in 1900 with a peak of 0.5 million in 1930. In the lower Hudson, no treatment was provided to 3 million people in 1900, increasing to over 6 million by 1938. From the mid-1930s to the late-1980s, the population discharging untreated sewage steadily declined as raw discharges received primary treatment, which typically removes 30 percent of the biochemical oxygen demand (BOD) and total suspended solids (TSS) load. Following master plans from the Metropolitan Sewerage Commission (1912), primary WTPs were constructed in 1924 at Passaic Valley, New Jersey and in Yonkers, New York in 1933. By 1938, three plants were discharging to the East River (Tetra Tech and Stoddard, 2000; Stoddard et al., 2002). By 1952, a total of seven primary WTPs were operational in New York City in the study area. The population served by primary facilities increased from 1.05 million in the late 1930s to a peak of 2 million in the 1960s. Completion of Manhattan's North River WTP in

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