Trade-offs across values in cesspool management highlight challenges to policy making.

On-site Sewage Disposal Systems (OSDS) are globally common, and in Hawai'i they present a risk of contamination to drinking water sources and nearshore waters. State legislation has commanded that all cesspools are to be banned by 2050, thus requiring tens of thousands of systems to be converted in the coming decades. This project followed a participatory structured decision-making (SDM) approach to collaboratively design cost-effective and equitable solutions for thousands of cesspools in the high elevation areas of north Maui, Hawai'i.

High rate biological contactor system using waste activated sludge from trickling filter/solids contact process.

A high-rate biological contactor process (HRBC) can be used as primary treatment instead of a clarifier to remove particulate, colloidal and soluble fractions of organic matter via biosorption plus flotation and divert it to anaerobic digestion for methane production, simultaneously reducing secondary aeration energy demand. Pilot and bench tests were conducted at a range of contact times (15-60 min) and contactor dissolved oxygen (DO) (0.2-2.

Anaerobic-aerobic biofilm-based digestion of chemical contaminants of emerging concern (CEC) and pathogen indicator organisms in synthetic wastewater.

The efficacy of biofilm based anaerobic-aerobic treatment to reduce caffeine, carbamazepine, and three estrogens (Estrone (E1), 17β-estradiol (E2), and 17α-ethynylestradiol (EE2)), as well as E. coli (CN-13) and F+ specific coliphage (MS2), from synthetic wastewater was investigated. Results showed no observable reduction of carbamazepine by either anaerobic or aerobic biofilms over a dosing period of 51-days followed by an additional 23 days of observation.

Adsorption of 1,2,3-Trichloropropane (TCP) to meet a MCL of 5 ppt.

1,2,3-Trichloropropane (TCP) is a groundwater contaminant in the drinking water aquifers in Hawaii and some other states. Granular activated carbon (GAC) has been used for 30 years to treat approximately 60 million gallons per day of TCP-contaminated groundwater in Hawaii. The State of Hawaii's current maximum contaminant level (MCL) for TCP is 600 ng/L (ppt), and consideration is being given to lower the MCL to 5 ppt.

Life cycle assessment comparison of activated sludge, trickling filter, and high-rate anaerobic-aerobic digestion (HRAAD).

This paper conducts a comparative assessment of the environmental impacts of three methods of treating primary clarifier effluent in wastewater treatment plants (WWTPs) through life cycle assessment methodology. The three technologies, activated sludge (AS), high rate anaerobic-aerobic digestion (HRAAD), and trickling filter (TF), were assessed for treatment of wastewater possessing average values of biochemical oxygen demand and total suspended solids of 90 mg L(-1) and 70 mg L(-1), respectively. The operational requirements to process the municipal wastewater to effluent that meets USEPA regulations have been calculated.

Enhanced nitrogen removal with an onsite aerobic cyclic biological treatment unit.

Coastal Zone Act Reauthorization Amendments (CZARA, Section 6217) necessitate the requirement that onsite wastewater disposal units located near impaired surface waters or groundwater to provide at least 50% nitrogen removal. Approximately 38% of Hawaii households use onsite systems including septic tanks and cesspools that cannot meet this requirement. Upgrades to aerobic treatment units (ATUs) are a possible compliance solution.

Condition assessment survey of onsite sewage disposal systems (OSDSs) in Hawaii.

Onsite sewage disposal systems (OSDSs) are the third leading cause of groundwater contamination in the USA. The existing condition of OSDSs in the State of Hawaii was investigated to determine whether a mandatory management program should be implemented. Based on observed conditions, OSDSs were differentiated into four categories: 'pass', 'sludge scum', 'potential failure' and 'fail'.

Green roof hydrologic performance and modeling: a review.

Green roofs reduce runoff from impervious surfaces in urban development. This paper reviews the technical literature on green roof hydrology. Laboratory experiments and field measurements have shown that green roofs can reduce stormwater runoff volume by 30 to 86%, reduce peak flow rate by 22 to 93% and delay the peak flow by 0 to 30 min and thereby decrease pollution, flooding and erosion during precipitation events.

Pilot-scale in situ bioremediation of HMX and RDX in soil pore water in Hawaii.

A nine-month in situ bioremediation study was conducted in Makua Military Reservation (MMR) in Oahu, Hawaii (USA) to evaluate the potential of molasses to enhance biodegradation of royal demolition explosive (RDX) and high-melting explosive (HMX) contaminated soil below the root zone. MMR has been in operation since the 1940's resulting in subsurface contamination that in some locations exceeds USEPA preliminary remediation goals for these chemicals. A molasses-water mixture (1 : 40 dilution) was applied to a treatment plot and clean water was applied to a control plot via seven flood irrigation events.

Survey of attitudes and perceptions of urine-diverting toilets and human waste recycling in Hawaii.

Urine constitutes only about 1% of domestic sewage but contains 50% or more of the excreted nutrients and chemicals like hormones and pharmaceutical residues. Urine diverting toilet (UDT) systems can be considered a more sustainable alternative to wastewater management because they allow nutrient recycling, reduce water use, and allow source-separation of hormones and chemicals that can harm the environment. An online survey was conducted to determine whether UDTs are acceptable to the general public in Hawaii and if attitudes and perceptions towards it and human waste (HW) recycling vary with age, sex, level of education, religious affiliation, ethnicity, and employment status.

Molasses enhanced phyto and bioremediation treatability study of explosives contaminated Hawaiian soils.

A 15-week treatability study was conducted in a greenhouse to evaluate the potential effects of molasses on the bioremediation and phytoremediation potential of Guinea Grass (Panicum maximum) for treating energetic contaminated soil from the open burn/open detonation area of the Makua Military Reservation, Oahu, HI (USA). The energetics in the soil were royal demolition explosive (RDX) and high-melting explosive (HMX). Among the 6 treatments employed in this study, enhanced removal of RDX was observed from treatments that received molasses and went to completion.

An economic appraisal of using source separation of human urine to contain and treat endocrine disrupters in the USA.

Elevated concentrations of estrogens in natural waters pose a significant threat to public health and aquatic ecosystems. Both natural (estrone, 17β-estradiol and estriol) and synthetic (17α ethynylestradiol) estrogens, ubiquitous in wastewater effluents and receiving waters, have been shown to affect the endocrine system of human and aquatic life. The effects vary from cancer to sex reversals at levels as low as parts per trillion in sensitive organisms.

Modeling the performance of hazardous wastes removal in bioaugmented activated sludge processes.

An enricher-reactor process in which acclimated biomass is grown in an offline reactor on high concentrations of enrichment substrates was used to bioaugment a conventional activated sludge process to a toxic compound, 1-amino naphthalene. Various levels of bioaugmentation, ranging from 1 to 16% mass ratio of augmented cells to indigenous cells, were evaluated in laboratory-scale reactors. The experimental results showed that bioaugmentation can enhance toxic compound removal, increase resistance to shock loading, and reduce the time required for acclimation to the toxic compound.

Modeling ozone mass transfer in reclaimed wastewater.

Ozone mass transfer in reclaimed water was evaluated at pilot scale to determine mass-transfer characteristics and reaction kinetics and to assess the use of oxygen as a surrogate to measure this process. Tests were conducted in a 40-L/min pilot plant over a 3-year period. Nonsteady-state mass-transfer analyses for both oxygen and ozone were performed for superficial gas flow rates ranging from 0.

Determination of biodegradable dissolved organic carbon using entrapped mixed microbial cells.

Several methods for determining biodegradable dissolved organic carbon (BDOC) in water have been developed within the last two decades. However, the problem with most of these methods is the length of time required for the start-up (colonization) and/or determination from days to weeks. In this study, a simple and rapid continuous bioreactor procedure using immobilized cells was developed for BDOC determination.