Wastewater & Biosolids Phytoremediation

Treating wastewater, while producing biomass

New standards for the management of municipal wastewater effluent will impose financial hardship on many smaller communities. Meeting these higher performance standards typically requires new treatment systems and upgrades that are expensive to design, build and operate. There are viable alternatives to traditional methods. This is where Bionera can help.

FACT: Developing a system to dispose of municipal wastewater, by using it to irrigate and fertilize a short rotation willow crop, can be as little as 40 percent of the cost, compared to a conventional engineered waste treatment system.

Fast-growing, easily propagated willow plantations

Irrigating willow plantations with municipal wastewater has proven to be an economically and environmentally sound option for several western Canadian communities. Using elite varieties of willow, these plantations:

  • grow quickly
  • absorb pollutants efficiently
  • re-sprout quickly after harvesting of aboveground biomass
  • adapt well to underutilized land

Municipalities that choose a plantation system to manage wastewater discharges enjoy numerous benefits, including:

  • substantially reduced capital and operating costs, when compared to conventional treatment plants
  • elimination or reduction of annual wastewater discharge, thus mitigating the associated environmental liabilities
  • improved landscaping and screening around wastewater lagoons
  • increased wildlife habitat, for birds and small mammals. Willows are also a source of nectar for bees
  • using harvested biomass in district heating of public buildings
  • attracting new residents and businesses who support environmentally and fiscally responsible municipal operations, creating new habitat for wildlife, particularly birds

FACT: Research has shown that one hectare of planted willows can dispose of 5 million litres of treated wastewater effluents per year.

Biosolids disposal solutions, while producing biomass

Larger municipalities, and cities with dewatering facilities, can dispose of biosolids by incorporating them with marginal soils, on poorer agricultural land. The increased nutrients are then absorbed by the fast growing willow, addressing four issues:

  • Provide innovative ways to dispose of biosolids on non-agricultural crops
  • Improve soil nutrients and structure on marginal agricultural land over time, through the addition of biosolids and willow leaf matter
  • Enhanced landscaping and screening around wastewater lagoons
  • Provide economical biomass, where chips can be used for bioenergy, compost additive, or landscaping material. 

 

Additional sustainable community benefits

Willow plantations also offer numerous benefits to communities focusing on sustainable development. These include:

  • using harvested biomass in district heating of public buildings
  • attracting new residents and businesses who support environmentally and fiscally responsible municipal operations
  • creating new habitat for wildlife, particularly birds

 

Growing willow for phytoremediation

agricultural land over time, through the addition of biosolids and willow leaf matter

How much land do I need to establish a willow plantation?

The amount of land required to establish a willow plantation depends on the project and its location.

Where does willow grow best?
Willow varieties have been developed that grow well in many diverse locations across the US and Canada. They tolerate marginal growing conditions, including a wide range of soil acidity and salinity that would otherwise limit conventional agriculture. Willow grows faster in a wet environment, but an annual average rainfall of 20 inches is sufficient. Willows used for municipal wastewater projects benefit from the ongoing irrigation, during the growing season.

What other growing conditions are required?
The majority of willow crops are grown in a manner similar to row crops such as corn and beans. Like other farm crops, willow requires full light and use of available soil moisture, so weed suppression is critical during the first two years. After that, willow’s robust root system supports rapid early growth that pushes new shoots past weed competition and shades out the ground.

How does willow compare to other crops?

Willow compares favourably to other agricultural crops. Large-scale production is achieved using proven planting and harvesting methods.

Willow is planted in a twin-row system to match conventional row-crop equipment and energy crop harvesting equipment. The system is geared toward efficient harvesting and involves lower labour, machinery, and chemical input than traditional agricultural row crops.

Unlike other crops, willow grows for two or three seasons between harvests, with a steady supply achieved by staggering the planting. After harvesting, willow re-grows vigorously. Soil nutrients can be replaced by recycling ash from combustion, along with modest applications of nitrogen.  This ancient crop system is known as a coppice, or dense thicket of plants, because each plant re-grows vigorously after being cut back. 

How is willow harvested?

Willow crops are harvested on a two- or three-year rotation, depending on soil, climate and precipitation. The stems are cut and chipped in a single-pass operation using a forage harvester equipped with a specially designed cutting head. Other harvest options, including billeting and baling, can extend shelf life and provide drying advantages. Mean yields of 6 dry tons per acre per year can be achieved, with many harvests from a single planting to provide a crop life of 25 to 30 years.  Additionally, cuttings can be harvested to provide planting material to new fields or to re-stock the original field at the end of the 25-30 year cycle.

Providing support & expertise

Drawing on over 25 years of industry leading expertise in forest nursery crops, we can help you plan, build and manage large-scale willow plantations designed to supply stable sources of purposely-grown biomass.

We provide all the support you need throughout the growing cycle, including:

Consultation. We listen to your needs; analyze your growing site, then design a custom plantation with selected crop varieties for maximum yield and speed of growth.

Cuttings supply. As a member of the Willow Biomass Group, we provide access to willow varieties that were specifically developed for short-rotation, fast-growing woody biomass crops.

Planting. We can provide one of two styles of tractor-mounted mechanical planters, depending on project size and soil conditions. 

Harvesting. For projects up to 300 acres, we can provide a specialized tractor-mounted PTO driven harvester/chipper. For larger projects, we can help you select the right equipment that meets your specific needs or provide alternate harvesting solutions. 

On-site support. We can provide on-site assistance during crop establishment and initial harvesting years to help optimize your operations.  

From designing fast-growing plantations and supplying cuttings, to managing and harvesting crops, we’re committed to helping our customers produce successful willow plantations.