Table 3.

SWOT analysis for IHE wastewater treatment methods.

Treatment method	Strengths	Weaknesses	Opportunities	Threats	References
Separation	•Simple method •Removes solid chunks as well as grit or dust from wash down of equipment	•Does not remove dissolved contaminants •Precipitation of energetics due to cooling	•Can be used in conjunction with other treatment methods	•Already fitted to many facilities	(Hammer and Hammer, 2001)
Electrolysis	•Cheap carbon electrodes make running costs low1	•Not proven on all IHE1 •Large power consumption2 •Precipitate is still energetic2	•Solid waste has potential for reuse or recycling2	•Not currently proven at industrial scale1	1 (Wallace et al., 2009) 2 (Cronin et al., 2007)
Photolysis	•Can destroy some energetic materials such as RDX and TNT3	•Not proven to work on IHE5 •Peroxide requires trained operators and equipment4	•Treatment only using UV could be discharged without polishing step5	•Not currently proven at industrial scale5	3 (Bordeleau et al., 2013) 4 (Alnaizy and Akgerman, 1999) 5 (Mahbub and Nesterenko, 2016)
Bi-metallic reduction	•No external energy input required7 •Complete degradation of NTO and RDX8,9	•Metallic nanoparticles cause environmental damage7	•Potential to retrofit to current column-based systems	•Not currently proven at industrial scale8	7 (Koutsospyros et al., 2012) 8 (Kitcher et al., 2017) 9 (Wanaratna et al., 2006)
Fenton oxidation	•Has been shown to destroy IHE10	•Requires very strong solvents11 •Produces a toxic waste product12	•Method likely to work on future energetic materials10,11	•Reluctance to increase staffing and reagent costs for required materials13	10 (Felt et al., 2013) 11 (Liou et al., 2003) 12 (Zoh and Stenstrom, 2002) 13 (Bautista et al, 2007, 2008)
Microbial degradation	•Has been shown to completely degrade all IHE14,15	•Systems are very sensitive to changes in pH, temperature and IHE concentration16	•Potential uses for sludge generated e.g., fertiliser17	•Suitability limited to larger facilities	14 (Weidhaas et al., 2018) 15 (Madeira et al., 2017) 16 (Platten et al, 2010, 2013) 17 (Karthikeyan and Spain, 2016)
Adsorption	•Low-cost18 •Proven to work on all IHE19,20,21,22 •Many LAP facilities already have adsorptive treatment systems18	•IHE is trapped in material matrix, not destroyed18 •Chemical regeneration results in concentrated IHE solution	•Use of biochars can reduce carbon footprint21	•High solubility of some IHE may saturate adsorbents more quickly, negating cost advantage22	18 (Hoffsommer et al., 1977) 19 (V. M. Boddu et al., 2009) 20 (Morley and Fatemi, 2010) 21 (Todde et al., 2018) 22 (Fawcett-Hirst et al., 2020)