## 1 Introduction  
Water resource recovery facilities (WRRFs) produce treated organic solids known as biosolids. Biosolids have characteristics that make them valuable for beneficial reuse via land application. For example, biosolids are a good source of organic matter (30-40%) and, depending on the treatment technology, they can be rich in nutrients like nitrogen (3%), phosphorus (1.5%), and potassium (0.7%) [1]. Biosolids can also improve soil structure and provide the soil with additional iron [1].  
Consistent with these benefits, a survey conducted in 2018 found that 53% of wastewater solids produced in the United States are treated and beneficially reused as land-applied biosolids, primarily on agricultural lands [2]. According to the survey, of the remainingbiosolids that are not land applied, 30% are landfilled and 15% are incinerated. Thus, the land application of biosolids has the added benefit of conserving landfill space [1]. Small WRRFs are more likely to landfill biosolids because they deem it too difficult to set up a beneficial use program [3].  
Many communities are interested in producing biosolids that are classified as Class A biosolids, which must meet stringent regulations for pathogen and indicator organism (PIO) levels and organic stabilization. Conventional processes for producing Class A biosolids include processes to further reduce pathogens (PFRPs), which include Composting, Heat Drying, Heat Treatment, Thermophilic Aerobic Digestion, Beta Ray Irradiation, Gamma Ray Irradiation, and Pasteurization [4]. With the possible exception of Composting, these are all expensive, high-maintenance processes, and most are energy-intensive. Unfortunately, many WRRFs serving small communities (defined as having a population of \(\leq\)10,000 people and wastewater flow rates of \(<\)1 \(\times\) 10\({}^{6}\) gal/day [5]) lack the capital resources and personnel and other operating requirements for implementing a PFRP. Increasingly, these WRRFs are interested in pursuing technologies that minimize the capital, operational, and maintenance costs associated with biosolids production, as well as the overall energy footprint [6; 7]. Fortunately, low-cost, low-technology (LCLT) alternatives are available and being used successfully at WRRFs in the U.S. and elsewhere. LCLT Class A biosolids treatment processes that are currently being used in full-scale treatment systems include long-term Lagoon Storage, Air Drying, Lagoon Storage Plus Air Drying, and Cake Storage [8].  
LCLT processes are attractive to small WRRFs due to their low capital costs and simple designs. However, are LCLT alternatives better for the environment than PFRPs? The overall goal of this study was to examine the sustainability of conventional and LCLT processes at small WRRFs. Specifically, this investigation is part of a broader study that evaluated the sustainability of five Class A biosolids treatment processes, including three conventional processes--Composting, Direct Heat Drying, and temperature-phased anaerobic digestion (TPAD)--and two LCLT processes--Air Drying and long-term Lagoon Storage followed by Air Drying (hereafter referred to as Lagoon Storage). This article presents the results obtained when the processes were compared on the basis of their environmental impacts using a life-cycle assessment (LCA) approach and is intended to provide guidance to smaller WRRFs that are interested in the environmental implications of their decision to select one of these processes.