Chapter 5: Aquatic Plants, Macrophytes, Halophytes, Hydroponic Vegetables, Trees, and Agroforestry in Ecological Wastewater-Treatment Systems

Chapter 5: Aquatic Plants, Macrophytes, Halophytes, Hydroponic Vegetables, Trees, and Agroforestry in Ecological Wastewater-Treatment Systems -- Selected Color Photographs

Introduction

In nature, plants (with associated microorganisms and organisms) growing in aquatic and terrestrial environments are important for waste filtering, degradation, and transformation. Researchers and ecological designers have long recognized plants' ecosystem functions in wastewater purification; they have incorporated aquatic plants, also called macrophytes, as crucial components in ecological and natural wastewater-treatment systems to stimulate "nature's way" of treating wastewater (i.e., how natural processes act on wastewater). Plants also can be cultivated to combine wastewater treatment with agriculture and aquaculture, as in China, where people for at least 2,000 years have used aquatic plants and trees to recycle nutrients in organic wastes and wastewater; the plant biomass generated is then composted for fertilizer, used as green fodder and fed to domestic animals, or grown as crops and consumed directly as grains, vegetables, and fruits. Plants also can be integrated in agricultural landscape design and management, as in Estonia, which has used vegetated bioponds, bioditches, buffer strips, and moor filters to prevent water pollution by agricultural and municipal runoff into natural waterways. A wide variety of ways to incorporate algae, macrophytes, and microphytes (tiny aquatic plants) in fully operating and experimental ecological wastewater-treatment systems will be discussed in this chapter.

Photographs (Row 1): Acorus grammineus (variety "Ogon")

Views of an evergreen macrophyte, Acorus grammineus (variety Ogon), commonly called Golden Acorus, which can be planted in shallow water and grows to 1 foot tall. The aquatic plant can be planted in both sunny or shady areas of the natural wastewater-treatment system. (Photographs by Jo-Shing Yang)

Photographs (Row 2): Saggitaria latifolia
Views of Sagittaria latifolia Willd., often called arrowhead, wapato, or arrow leaf. It grows edible tubers (wapato) underground, which were used as food by Native Americans. Native to North America, it is a rhizomatous perennial that grows in shallow water of ponds, wetlands, lake margins, and ditches. It can grow to 3 feet tall and has white, three-petaled flowers. (Photographs by Jo-Shing Yang)

Photographs (Row 3): Saggitaria lancifolia (Variety "Rubura")

The bulltongue arrowhead (Saggitaria lancifolia L., var. "Rubura") with red stems, which can grow 3 to 4 feet tall. Also called "duck potato," it is considered an invasive species in some ecosystems; this perennial provides food (underground, potato-like corn) for ducks and mammalian wildlife. (Photographs by Jo-Shing Yang)

Photographs (Row 4): Mimulus gattatus

Views of Mimulus gattatus DC., common (yellow) monkeyflower, seep monkeyflower, or creek monkeyflower, growing in nursery containers. Native to North America, this macrophyte is a perennial commonly found in natural marshes, along stream-banks, near springs, and in wet meadows. It can be planted in both constructed wetlands and vegetated buffer systems for wastewater polishing and pollution prevention. When using this species outside North America, efforts must be made to prevent its spread into natural ecosystems. Harvested plant biomass can be used to produce energy (biogas, consisting of 65% methane) and biological fertilizer (compost). (Photographs by Jo-Shing Yang)

Photographs (Row 5): Mimulus gattatus
Views of young Acorus grammineus "Pusillus" Soland. in Ait. ("Variegatus"). This species has three varieties (Ogon, shown here in Row 1). Commonly called Japanese sweetflag, variegated acorus, or grassy-leaved sweet flag, it is a perennial that grows in marshes and streambanks. It can reach 18 inches; it has shiny, dark-green, narrow leaves forming grassy tufts (the spread is 6 to 8 inches). This species can be used in constructed wetlands for wastewater treatment. (Photographs by Jo-Shing Yang)