While phosphorus and nitrogen are indispensable for the growth of aquatic flora, nutrient-rich wastewater results in eutrophication — an excessive growth of algae and plankton in bodies of water — which impairs freshwater and coastal marine ecosystems. To preserve these vital bodies of water and prevent eutrophication, wastewater treatment plants a...
Ideally, a sewer line should last 50 to 100 years, depending on the materials used to build the pipes. The gradual deterioration of sewer pipelines is caused by cracks, settling, tree root intrusion and other disturbances that develop over time. These deteriorating conditions affect the amount of inflow and infiltration entering systems, particular...
PFAS, or Per- and Polyfluroalkyl Substances, contamination of groundwater and drinking water exposes us to chemicals that eventually bioaccumulate in our tissues. Preliminary studies indicate the potential health effects of PFAS include altered immune and thyroid function, liver and kidney diseases, adverse reproductive and developmental outcomes a...
As a radioactive element, radium is present in varying amounts in rocks and soil within the Earth's crust. While surface water is usually low in radium, groundwater can contain high levels of radium, potentially leading to radium in drinking water. Radium is typically found in drinking water in regions where it is present in the granite bedrock sur...
Sludge is a solid byproduct produced during wastewater treatment. It contains a mixture of water, nontoxic organic compounds, toxic pollutants (heavy metals and chemicals), inorganic compounds, pathogens and other microbial pollutants. It is typically classified into two types:Primary sludge. This is a byproduct of the preliminary treatment of wast...
Before sewage/wastewater is discharged or reused, it must be properly collected from homes, businesses and industries. A wastewater or sewer collection system is primarily designed to collect and move flows to a downstream treatment plant. As sewage flow moves, it encounters pressure and gravity. The construction of sewer structures such as collect...
In a sewage or wastewater collection system, raw sewage travels underground through sloped pipelines (also called gravity pipelines). However, when the elevation of the source is not sufficient for gravity flow, digging for sewer pipes in excessive excavation depths is necessary. Installing a wastewater lift station at specific points in a gravity ...
Many rural communities across the United States rely on wastewater treatment processes that fall short of environmental and public health protection standards. The U.S. Environmental Protection Agency (EPA) and the U.S. Department of Agriculture (USDA) have introduced several funding mechanisms to improve water and wastewater infrastructure in smal...
Lagoon wastewater treatment systems are mostly found in small, rural and tribal communities in the U.S. and are used as the only method of treating community wastewater. Small communities of fewer than 3,000 residents usually prefer sewage lagoons because of their energy efficiency and low costs. However, recent wastewater treatment requirements, i...
To help public sector officials minimize fire and explosion hazards, the National Fire Protection Association (NFPA) publishes preventative requirements, fire codes and building standards. Used in alignment with state building codes, the NFPA 820 standard is specific to wastewater collection, transportation and treatment plants. Methane generated b...
Hindsight might be 20/20, but foresight is pretty essential when it comes to infrastructure planning. Too often, communities grow in a piecemeal type of way: A subdivision is built, so sewer lines are put in to serve the neighborhood. A strip mall goes up next door, tying into those same lines. The once quiet street above the sewer that was easy to...
Adding air directly to wastewater is considered a critical step in wastewater treatment because it facilitates the biodegradation of organic pollutants. However, this vital aeration process also consumes the most energy at wastewater treatment plants (WWTPs). Given that aerobic reactors in the secondary treatment activated sludge process account fo...
Aeration – or the addition of oxygen – is one of the most critical and energy-intensive processes in wastewater treatment, consuming up to 50 to 60% of the overall energy required by a wastewater treatment plant (WWTP). Aeration produces dissolved oxygen (DO) to facilitate the growth of microorganisms and is used across all stages of wastewater tre...
Long-term, comprehensive planning is key to successful wastewater treatment systems. Without a strong plan, a community's ability to facilitate development may be limited by its wastewater infrastructure – or worse, its rivers, lakes, streams and residents' basements may be at risk from failing wastewater infrastructure. A Master Plan will consider...
Under the auspices of the Safe Drinking Water Act, the U.S. Environmental Protection Agency applies the secondary treatment standards for wastewater as national minimum requirements for discharges from wastewater treatment plants to U.S. surface waters. Depending on receiving water conditions or specific state regulations demanding higher-quality e...
During the wastewater treatment process, the primary and secondary stages aim to remove the majority of suspended solids and organic contaminants before the effluent progresses to tertiary treatment. The primary treatment removes nearly 60% of settleable solids and the secondary treatment uses bacterial decomposition to remove nearly 85% of organic...
In wastewater treatment, the clarification process removes suspended solids using gravity. The secondary function of a wastewater clarifier is to remove accumulated scum or floating matter on the surface. This blog post discusses the primary and secondary clarification processes, the types of wastewater clarifiers and how an experienced wastewater ...
Even after the primary physical treatment, wastewater contains large quantities of dissolved and colloidal organic material. Though primary treatment can reduce biochemical oxygen demand by as much as 30%, the treated effluent still requires a secondary treatment that uses complex biological processes to remove organic contaminants. The goal ...
With more than 2,800 contaminated sites in 50 states, public concern about per- and polyfluoroalkyl substances (PFAS) contamination has grown, yet a great deal about these so-called "forever chemicals" remains unknown. Faced with such uncertainty, the U.S. Environmental Protection Agency (EPA) has set no formal limits on a moving target like PFAS d...
Conventional wastewater treatment involves several physical, chemical and biological processes to remove solids, organic matter and nutrients from wastewater. Primary treatment removes coarse solids and other large materials from wastewater. At this stage, municipal wastewater treatment technologies eliminate organic and inorganic solids and floata...
